Tartu Observatory
Annual Report, 2003

Contents





Foreword

Foreword The present report of the activities of Tartu Observatory has its traditional contents and structure. It is the 13th issue in English, whereas the chapters in Estonian are added only for second time.

First reminescences from the year 2003, connected with the confusion around target financed research and discussions about the system of financing research in Estonia, are perhaps not so good. There were, however, more important events, like elections of the Parliament (Riigikogu) and formation of the new Government in Estonia. Surprisingly enough, our colleague and partner Academician Ene Ergma was elected to the Speaker of the Parliament. A slight feeling of pitiness that there in no more Professor of astrophysics in the University of Tartu is weighted up by the pride that an astronomer occupies the second important position in the Republic of Estonia. The new Minister of education and research was successful in raising additional funds from the state budget in order to release the tensions around target financed projects. In our Observatory, the sum for target financed projects remained somewhat less than it was in 2002. However, it was possible to increase salaries for the whole staff a little bit.

The amount of scientific production is expressed by 29 papers in journals and 22 in conference proceedings. In particular, compiling a voluminous "Handbook of Estonian Solar Radiation Climate" by Viivi Russak and Ain Kallis should be mentioned. This book, devoted to the memory of Academician Juhan Ross (1925-2002), was published by the Estonian Meteorological and Hydrological Institute.

After a long time, a member of our staff defended a PhD thesis. It was Ivan Suhhonenko, who moved temporarily to Finland after that, to tighten our collaboration with the Tuorla Observatory. Although the number of people employed by our Observatory decreased a little bit during 2003, we were able to employ several young researchers in the beginning of 2004.

The group of remote sensing of atmosphere organized meeting of the Nordic Ozone Group in Tartu in March 2003, attended by 23 scientists. On June 3rd, Estonian seminar on remote sensing, assembling 50 people, was organized at the Observatory. Our international contacts continued in usual ways. As one aspect of such a collaboration, our cosmologists participated in two project proposals, submitted to the European Community 6th Framework Programme. The competition, though, was high, and those projects did not cross the threshold. New attempts with modernized projects will be made. In 2003, a new subprogramme within the European Union programme OPTICON was launched, enabling astronomers from Estonia among others to use the big European telescopes - if only we could make competitive proposals for observing time.

In two successive years, the Commission for National Science Prizes has honoured astronomers. In 2002 Academician Ene Ergma was awarded the Prize in exact sciences, while in 2003 Academician Jaan Einasto received the main Prize - for a lifelong research work. His research activities are still continuing at admirable pace. Let this recognition make a strong impression to everyone of our scientists, in order to find this "right nut", cracking of which would help to attain and keep the world top level in research.


Laurits Leedjärv

Director

Summary

Research projects and grants

Most of the finances for basic research in Estonia are channelled through target financed projects. In 2003, research in the framework of three new projects was started:

In addition, the Estonian Science Foundation financed 12 grant projects from our Observatory (1 kEEK = 1000 EEK = 63.9 EUR):

  1. Grant 4140: V. Russak - Study of variable components of the atmosphere and their variability by optical sounding method - 90 kEEK.
  2. Grant 4695: J. Einasto - Evolution of the Universe from the past to nowadays - 230 kEEK.
  3. Grant 4696: T. Nilson - The analysis of time series of satellite images to estimate vegetation change - 185 kEEK.
  4. Grant 4697: J. Pelt - High precision statistical and computational methods in astronomy - 70 kEEK.
  5. Grant 4698: U. Peterson - Mapping afforestation of abandoned agricultural land in Estonia and its neighbouring countries with remote sensing data - 135 kEEK.
  6. Grant 4699: M. Sulev - Radiation regime, architecture and biomass production of the energy forest (willow and grey alder) in Estonia - 150 kEEK.
  7. Grant 4701: A. Sapar - Stellar spectra and radiative transfer: from theory to model calculations - 100 kEEK.
  8. Grant 4702: J. Vennik - Structure of galaxies and their subsystems at different epochs - 180 kEEK.
  9. Grant 5003: T. Kipper - Evolution of luminous non-stable stars - 200 kEEK.
  10. Grant 5004: O. Kärner - Modelling the global temperature series - 35 kEEK.
  11. Grant 5347: M. Gramann - Dynamical evolution of superclusters, clusters and galaxies in the Universe - 80 kEEK.
  12. Grant 5348: U. Veismann - The influence of atmospheric optical parameters on the ground-level solar UV radiation - 100 kEEK:


Some other projects and contracts:

A scientific report about the activities within all these projects and topics will be given in Chapters 6-8.

Personnel and structure

There were no changes in the structure of the Observatory during 2003.

On May 1, our former colleague Liia Einasto left us forever in the age of 73 years. She was a mathematician-programmer who helped many astronomers to formulate their complicated computation demands in a computer-understandable language.

On September 1, our former colleague Leo Sorgsepp (75) passed away. He was a scientist who developed himself from an observer of close binary stars into a theoretician of elementary particles. His original style of thinking remains in our memories.

There was one more painful loss on October 26, when temporary research associate from the group of remote sensing of vegetation Vello Ross died in his 68 years. V. Ross was our staff member for a long time. After working meantime in the Estonian Agricultural University, he returned to the Observatory in 1993, to perform the project on energy forest.

In March 2003, research associate T. Kübarsepp left the Observatory, starting from November 1, technician V. Aas does not belong to our staff. There were no new people employed during the year, and as of January 1, 2004 there were altogether 54 people on permanent positions at the Observatory. Of this number 30 people are on the positions of research associates and senior research associates. Adding three engineers, the director and the vice-director on research brings the number of people directly involved in research up to 35.

Rewards

In 2003, a few of our scientists were publicly acknowledged by state or by different organizations. The most important event of this kind took place in the 85th anniversary of the Republic of Estonia (February 24th), when Academician Jaan Einasto was awarded the National Science Prize for a lifelong research work. His work in the field of dynamics of galaxies, dark matter and large scale structure of the universe has lasted for more than fifty years, and has gathered renown to himself and to the Tartu Observatory in the whole world.

In connection with its 150th anniversary, Estonian Naturalist's Society elected new honorary members. One of them is Jaan Einasto.

Estonian general scientific magazine "Akadeemia" evaluated the papers published in 2003. In the domain of realia the paper by Kalju Eerme "Unvariable climate would mean the end of history" was considered to be the best one.

The Heino Eelsalu fellowship foundation at the Estonian National Culture Foundation awarded the followship for 2003 to Viivi Russak (for compiling the "Handbook of Estonian Solar Radiation Climate") and to Ph.D. student of Tartu University Taavi Pae.

Instruments and facilities

There were no significant developments in the research equipment of the Observatory in 2003. As usually, the computer systems including both personal computers and the local server, were upgraded continuously. Preparations for widening the radio channel, connecting us with the outer world, were started.

The group of remote sensing of the atmosphere purchased a fiber optic spectrometer Avantes AvaSpec-256 in October 2003. Its working diapason is 240-440 nm and resolution 0.8 nm. Preliminary work connected with automatic data recording, calibration and data processing was started by U. Veismann, I. Ansko and M.Sc. student S. Lätt. The instrument opens a possibility for a more detailed recording of the solar spectral ultraviolet irradiance as compared to the previous broadband instruments. The spectral irradiance enables to adjust the UV radiative transfer in different atmospheric conditions as well as the impact of UV radiation on the biospheric species (agricultural, forest) and manmade materials (plastics, colouring matters).

M. Pehk elaborated an experimental copy of the field spectrometer for the reflectance measurements in plant canopies in the middle infrared spectral region.

Astronomical observations were continued as usually. The 1.5 m telescope was used for spectroscopic observations during 58 nights, and the 0.6 m telescope for photometric observations during 21 nights.

Budget

The total amount allocated from the state budget directly to the Observatory was 9731 kEEK and it consisted of 5635 kEEK for target-financed projects, 2426 kEEK for infrastructure, 1510 kEEK as grants from Estonian Science Foundation, and 160 kEEK for renovation (entrances to the main building).

The expenses were divided approximately as follows:

In addition we could use 787 kEEK from contracts with European Union and other organizations.

The mean monthly salary of research associates was approximately 8003 EEK (511 EUR) by the end of 2003.

Scientific council

The present list of members of our scientific council is as follows:

  1. L. Leedjärv, director, Ph.D. (chairman),
  2. T. Viik, vice director, D.Sc. (vice-chairman),
  3. J. Einasto, senior research associate, D.Sc., Est. Acad. Sci.,
  4. E. Ergma, speaker, Parliament of Estonia, D.Sc., Est. Acad. Sci.,
  5. M. Jõeveer, senior research associate, Ph.D.,
  6. T. Kipper, head of department, D.Sc.,
  7. A. Kuusk, senior research associate, D.Sc.,
  8. T. Nugis, senior research associate, Ph.D.,
  9. T. Nilson, head of department, D.Sc.,
  10. R. Rõõm, professor, University of Tartu, Ph.D.,
  11. E. Saar, head of department, D.Sc.,
  12. A. Sapar, senior research associate, D.Sc., Est. Acad. Sci.,
  13. U. Veismann, senior research associate, Ph.D.

The scientific council held 12 meetings in 2003. The following scientific reports were presented:

January - I. Pustylnik: Single and binary precursors of white dwarfs.
February - U. Haud: Neutral hydrogen components of the Milky Way.
March - T. Nilson: Data reductions for the plant canopy analyser.
April - T. Kipper: Unusual variable star V838 Mon.
May - P. Traat: On young and old galaxies and on pecularities of the evolutionary scenarios.
June - K. Annuk: On spectral variability of Wolf-Rayet stars.
October - A. Kuusk, M. Lang, T. Nilson: Reflectance spectra of the forest understorey.
November - I. Kolka: Stars with emission lines and photometric system for the GAIA satellite.
December - O. Kärner: The climate is hardly changing.

Some other activities of the council:

Public relations

Tartu Observatory continued to act as a popular destination of excursions, receiving about 6000 visitors in 214 groups in 2003. Our guides M. Ruusalepp, A. Puss, K. Annuk, I. Kolka, I. Pustylnik, L. Leedjärv, J. Vennik and T. Viik did a great job to introduce the visitors with the Observatory and with the news of astronomy and atmospheric science.

One more aspect of public relations should be mentioned. On May 29, the company Ösel Foods Ltd., a producer of juices and other soft drinks, held an open-air party at Tõravere to celebrate its 10th anniversary. Everyone of almost 250 party guests had an opportunity for sightseeing in the Observatory and in the Meteorological Station. According to the request by the party host, the guests were asked not to bring presents, but instead, to make a donation to Tartu Observatory for developing a virtual planetarium. Thanks to the donations, we have purchased a videoprojector and the program "Starry Night" which enable to project heavenly phenomena onto a big screen. We are grateful to all the 24 companies and persons who contributed into accomplishment of this project. In addition, the Nõo parish government financed purchase of the screen.

We organized two learning days, for the teachers of physics and mathematics from Tallinn and Jõgeva County, respectively, in order to inform them about the latest developments in astronomy. Several public nights were arranged to show the planets Jupiter, Saturn and Mars.

The Astronomy Club at the Old Tartu Observatory continued its activities: lectures, public demonstrations of the sky, excursions etc. Members of the Club together with M. Ruusalepp, K. Annuk and other staff members of the Observatory organized the 8th annual meeting of Estonian amateur astronomers at Tõravere. The main "acting person" of this meeting was the planet Mars to which a great part of lectures and observations were devoted (the latter were to a great extent inhibited by the weather). The meeting, held from August 8 to 12, attracted altogether 110 participants. For one day, they were joined by about 26 people, interested in weather forecasting.

As usually, our scientists gave public lectures, were interviewed in radio and TV broadcasts and answered many phone calls. The number of the latter considerably increased in October-November 2003 when there was an unexpected peculiar rise of the solar activity. The Ministry of Environment of Estonia ordered from U. Veismann a booklet "The Sun, Ozone Layer and Man".

We published the Observatory Calendar, it was the 80th year of issue.

Forward look

Look into the future is a little bit more optimistic in the beginning of 2004, than it was in several previous years. After a long time, the Government and the Parliament of Estonia seem to understand better the nature and the needs of research. In the state budget for 2004 all three main numbers of financing research - target-financed projects, infrastructure expenditures and grants of Estonian Science Foundation - are bigger than last year. Financing of the centres of excellence grew up significantly. Estonian government is designing a programme for renovating and improving the infrastructure of scientific institutes. Funds from European Union for the same purpose are looming on the horizon ...

However, this does not mean that we can concentrate just on our favourite research, and hope that life will be better of its own. We have to make effort, first of all to show to talented young people that research in astrophysics or atmospheric physics could be a promising future for them. Interest of students to our research is expressed, for instance, by the fact that in 2003 five Ph.D. students, specialized in astrophysics, started their studies under supervision of researchers from the Observatory. We hope that in the future those and other Ph.D. and M.Sc. students will be members of our staff, to whom we can pay the salary they deserve. Salary is very essential, but not the only aspect of working conditions for a scientist. High standards of research environment and tools are important, too. At present, the first steps of introducing the global computing system Grid into Estonia are taken. We must be ready to join it sooner or later. We must keep our telescopes, cameras, detectors etc. on the level which enables students to get idea, what the modern astronomical observations are like. The same principle concerns an equipment for atmospheric research.


Acknowledgements

Many associates were supported by various institutions throughout the world. Herewith we cordially thank:

Evolution of structure in the Universe from deep past until the present

Large-scale distribution of galaxies

J. Einasto and G. Hütsi, together with M. Einasto, P. Heinämäki, E. Saar, V. Müller, and D. Tucker continued the study of the galaxy density field of the Las Campanas redshift catalogue and the Sloan Digital Sky Survey (SDSS). When calculating the density field, the main problem is how to account for selection: we cannot see fainter galaxies in more distant regions. This will completely eliminate the clusters without bright galaxies from the survey, and will dilute the clusters, which contain some bright galaxies. In order to account for the selection effect, two methods were developed. In the first case the total luminosity of galaxy clusters is found on the basis of a special galaxy luminosity function. This function takes into account the fact that fainter galaxies cannot be observed far away, and differs from the traditional galaxy luminosity function. In the second method, cluster luminosities are corrected for the selection effect. Both the methods are statistically equivalent.

The density field was calculated using two smoothing radii, 0.8 and 10 Mpc. The first smoothing gives a high-resolution density field that allows to define galaxy clusters and to find their positions and luminosities. The large smoothing radius helps to define superclusters and to characterize the environmental density of clusters. The authors found 950-1285 density field clusters and 15-19 superclusters per a Las Campanas survey slice. The Sloan survey is somewhat deeper, thus the slices of this survey have 2300-2800 clusters and 16-24 superclusters per slice. It was found that the luminosity distribution of the density field clusters (the luminosity function) can be well represented by the Schechter function. The parameters of this function and their error distributions were determined, and the supercluster luminosity function was found.

Superclusters of galaxies

M. Einasto described the general properties of the superclusters, which are intersected by the slices of the Las Campanas survey. She determined the physical content of the superclusters (X-ray and radio clusters of galaxies), and the spatial structure. This analysis demonstrated what additional information on superclusters and on the supercluster-void network can be obtained, using deep, but thin slices of the spatial galaxy distribution.

Figure: The SDSS EDR density field clusters (black dots in the two narrow samples) together with rich Abell clusters (grey dots). The line-of-sight is chosen to look at the SDSS slices from the side. We have shown only these Abell clusters, which belong to rich (at least 8 member) superclusters.
The Northern SDSS slice (at the right) passes through several very rich superclusters, and this is probably the reason why the Northern SDSS most luminous clusters are about twice as luminous as their Southern counterparts (at the left).

M. Einasto demonstrated that the density field superclusters, which intersect the superclusters, defined by Abell clusters, are more rich and more luminous than the density field superclusters, which are located far away from the Abell cluster superclusters. These differences between the superclusters, and also the differences between galaxy groups in rich and poor superclusters, might be the cause for the differences between the SDSS survey density field groups in the North and in the South. The Northern part of the SDSS survey intersects a number of rich superclusters, but the Southern part lies in a relatively sparsely populated region, dominated by voids.

M. Einasto used also $N$-body models to study superclusters. She built model superclusters from the model cluster haloes and studied their spatial distribution and other properties.

Galaxy clusters

J. and M. Einasto studied the dependence of cluster luminosities on the density of their environment. They found that in a high-density environment (in central regions of superclusters) clusters are up to 10 times more luminous than in a low-density environment (in voids). The masses of clusters and superclusters are different also in different regions of the sky - the masses of rich clusters and superclusters in the Northern Sloan survey slice are about twice larger than those in the Southern slice. This result supports the notion of the hierarchy of systems in the universe - the cosmological environment has an important role in the formation and evolution of groups and clusters. The earlier studies of this hierarchy have focused mainly of the properties of voids.

These results were compared with the properties of simulated clusters, generated by $N$-body simulations. It was found that the luminosities and masses of simulated clusters depend on the density of their environment even more than found from observations - the contrast between the masses of clusters in high-density and low-density environments is higher. This can be probably explained by the better mass resolution of the numerical models. J. Einasto presented these results at a conference in Rio de Janeiro.

E. Tago continued developing the galaxy cluster database, together with H. Andernach (Guanajuato Observatory, Mexico). Presently the database contains 3430 cluster redshifts and velocity dispersions for 1595 clusters. The velocity dispersion data were used to estimate the mass-luminosity relation of the clusters and the average matter density of the universe $\Omega_m$, together with colleagues from Greece and Mexico. They found the value $\Omega_m=0.23$, in harmony with the generally accepted "concordance" cosmological model.

E. Tago began the study of the spatial distribution of galaxies in the recent deep surveys (the 2dF and the Sloan surveys). The 2dF survey is complete, with about 250 000 galaxy redshifts. The SDSS survey data consist of the preliminary EDR sample (about 40 000 redshifts) and the first regular data release DR1 (about 110 000 galaxy redshifts). Using cluster analysis, a catalogue of galaxy groups and clusters has been generated, in order to study the properties of the systems and to find their spatial density distribution. This study is continuing, the main problem at the moment is correction for the selection effects.

A student of Tartu University J. Liivamägi studied for his bachelor thesis (supervisor E. Saar) the problem of automatic determination of groups and clusters of different sizes for the new redshift catalogues, and of the reduction of the redshift space distributions to the real space. He used anisotropic wavelets and applied the technique to the early SDSS data. The first results, presented in the thesis, were good; the technique works, and J. Liivamägi is working on developing it into a practical tool.

M. Gramann and I. Suhhonenko studied the probability distribution of the peculiar velocities of galaxy clusters in standard cosmological models, where the initial density and velocity fields are random Gaussian fields. They used different recipes to compose galaxy clusters in the numerical simulations, the density-field based DENSMAX, and FOF, which is a standard cluster analysis method in statistics. They found that the peculiar velocity distribution of DENSMAX clusters is close to a Gaussian. On the other hand, the peculiar velocity distribution of low-mass FOF clusters differs from a Gaussian distribution, there are more high-velocity clusters than predicted by a Gaussian.

Galaxy groups

J. Vennik continued the photometric study of the galaxy group LGG 16 (with the main galaxy IC 65). He corrected the membership criteria for the group, using the luminosity and colour data for the group galaxies, obtained by the SExtractor data reduction package. The selection of new dwarf members was based on Binggeli's empirical relation between the central surface brightness and the total luminosity. The surface photometry, carried out for the brighter group members in the BRIHJK colours shows moderate distortions in the outer regions of the galaxies. The new photometric results, together with the results on the distortions in the distribution of the neutral hydrogen (H I), found previously by van Moorsel, lead to the conclusion that the group is gravitationally bound. They also show that the active star formation process in one of the bright members (UGC 608) of the group and in several dwarf companions is caused by interactions between group members.

M. Einasto studied the properties of galaxy groups in superclusters and compared the groups in different superclusters. She identified loose groups of galaxies in superclusters, defined by rich (Abell) clusters of galaxies, and also in superclusters, which do not contain rich clusters. Comparison of different group populations showed that galaxy groups in superclusters, which are defined by Abell clusters, are more rich, more massive and luminous than groups in superclusters without rich clusters of galaxies. Also, the groups at the outskirts of superclusters with rich clusters are poor and have smaller masses; galaxy groups are most influenced by their environment either close to rich clusters of galaxies or in the central regions of superclusters. In the outskirts of superclusters or far away from superclusters (in voids) the environment practically does not influence galaxy groups. This is the first paper that demonstrates the importance of the large-scale (supercluster-scale) cosmological environment to the evolution of galaxy groups.

Double and multiple galaxies

J. Vennik continued studies of interacting galaxies, together with a group of astronomers from different countries. This year they completed the photometric and spectroscopic studies of the galaxy pair IC 3639 and ESO 381-G009 (J. Vennik carried out the photometry). The CCD surface photometry in the BVR spectral bands and in the H$\alpha$ line showed that both members of the pair have a massive young bar, surrounded by star formation regions, which evidently directs the galactic gas into the centre of the galaxies and feeds the active Sy 2 type core of IC 3639. The core of its companion shows starburst activity. The interaction of the galaxies is also shown by the deformations of the outer parts of their discs - the isophotes of the discs of both galaxies are oriented towards their companion. These results allow to conclude that the galaxies have passed the perigalacticon that induced active star formation both in the cores of the galaxies and in their discs. The close passing-by lead also to moderate morphological perturbations and disc instability that caused the formation of the bar. The results have been published in Astrophysical Journal Suppl. Ser.

M. Jõeveer and A. Lõhmus added new data to their databases of double and triple galaxies, using data from literature and from internet. When analysing the collected data, they searched for methods, which would allow to distinguish between physical and optical systems of galaxies. The present data are not sufficient to determine this. The distinction is usually done on the basis of the mass-luminosity ratio of a system $f = M/L$; the problem is to determine the right threshold for this ratio. In previous studies the threshold has been chosen as a round value, $f = 100$ in Solar units (for $H_0$=75 km/s/Mpc); systems with a higher mass-luminosity ratio are considered to be optical.

As the members of physical systems influence each other to a greater (tight pairs) or smaller extent (loose pairs), the properties of member galaxies (luminosity distributions, traces of interaction, morphological types, spectra etc.) contain, in principle, information that can be used to determine the threshold for the mass-luminosity ratio. It was found that spectral data do not contain enough information about this threshold. On the other hand, the luminosity distributions, traces of interaction, and morphological types lead to an estimate of the value of the threshold, giving a bit higher result $f=120$.

Using this value, both the mean masses and mass-luminosity ratios of the systems grow, leading also to a larger role of dark matter in these systems.

Single galaxies

P. Tenjes and A. Tamm, a Ph.D. student of Tartu University, continued work on photometry of distant galaxies and on modelling their mass distribution. Study of distant galaxies can give us clues about the properties of the early structure of the universe. Using photometry data from the Hubble Space Telescope and spectroscopy from the Keck telescope, photometry of additional 4 disc galaxies at redshifts 0.5-0.9 was carried out. One of these galaxies belongs to the Hubble Deep Field sample. The mass-luminosity ratios for the discs (in the maximal disc approximation) were found as $M/L_B$ = 1.3, 0.62, 0.85 ja 2.1. The mean central surface brightness of the discs in the B band was found to be 21.4, as for the previously studied galaxies; this shows only a slight luminosity evolution. The results obtained for the 7 galaxies studied this far confirm that the distant (and early) galaxies are also surrounded by dark matter haloes. On the other hand, the luminosity distributions of distant galaxies differ from those of the local galaxies, the disk luminosity drops much faster in the outer regions of distant galaxies. Further study is planned to clarify this effect. The results have been published in Astronomy & Astrophysics.

Figure: Distant galaxies from the HST (Hubble Space Telescope) archive, all about the same size as our Galaxy. The left and the middle galaxies have the redshift of 0.5 (the universe was then about half the present age), and the redshift of the rightmost galaxy is 0.9. The middle galaxy is a typical HST object, the left one comes from the Hubble Deep Field program. These galaxies are similar, but the resolution of the leftmost galaxy is better, due to the so-called dithering technique, used for the Hubble Deep Field. The rightmost galaxy is also a common HST object; we see that its larger redshift changes the relative resolution (the galaxy is also about 0.7 magnitudes fainter than the others).

P. Tenjes and H. Eerik, a Ph.D. student of Tartu University, studied data on the subsystems of globular clusters of galaxies, in order to find correlations between the morphological type of a galaxy and the properties of its globular clusters. In earlier work, they had determined uni- or bimodality of the metallicity distributions of globular cluster systems. By now the galaxy sample consists of 113 galaxies with studied globular clusters. In this year the following correlations were studied:

1) the mean metallicities [Fe/H] of globular clusters - the general parameters of galaxies (their luminosity, the central colour index ($V-I$), the velocity dispersion and the form of the isophotes);
2) the mean metallicity of globular clusters - other parameters of the globular cluster system (their number, relative abundance, spatial distribution profile);
3) the mean metallicity of globular clusters - the density of the environment of the galaxy;
4) combinations of parameters of the globular cluster system.

For bimodal systems, the correlations were searched for separately for the metal-rich and metal-poor populations. Also, two luminosity classes were considered. The analysis has shown weak linear dependencies, with the correlation parameters $R^2 < 0.3$). The metal-rich populations give, in general, tighter relations. In several cases, instead of a gradual relationship, the parameters have a jump between the two luminosity classes. The results have been published in Astronomische Nachrichten.

Structure of the Galaxy

U. Haud began describing the structure of the H I profiles of the Leiden/Dwingeloo H I survey, to be published in Astronomy & Astrophysics. The work that will be described in the paper has been done in previous years, but discussions with E. Saar lead to the idea that a slightly different mathematical technique might lead to a better presentation of the results. Tests confirmed this assumption and thus the paper has been written in parallel with repeating the work with the new technique.

U. Haud started also working on new data. This was caused by the fact that the Leiden/Dwingeloo Northern H I survey is being extended to the South, and this survey is close to being completed. The observations have been done in the Radioastronomical Institute of Argentina, and the data are being processed in the Radioastronomical Institute of the Bonn University, Germany. U. Haud has been assigned the task to check the work done in Bonn. He separates the profiles reduced in Bonn into Gaussian components and carries out the statistical analysis of the profile parameters. For the moment, the work has gone through 5 iterations, which has lead to a considerable improvement of the profile baseline. The main problem at the moment is to improve the interpolation procedure between the Northern and Southern data - the present technique generates a high noise level in each 64th consecutive channel.

Figure: The minimum distance method (MDM) and the perturbation method (PM) for the simplest one-dimensional case. The circles denote the standard stars with known effective temperature. The derivative line, used by the PM method, is shown by a thin line, the value of the photometric parameter for a program star - by a horizontal dotted line, and the classification results (predicted values for the effective temperature) - by vertical dotted lines.

V. Malyuto continued classification studies in the framework of the GAIA space mission. One of the most important tasks for GAIA is to develop classification methods for the future GAIA photometric data, in order to determine the main physical parameters for large samples of stars in the Galaxy. V. Malyuto compared two most frequently used classification methods: the Minimum Distance Method and the Perturbation Method. The difference between these methods is illustrated in Fig. [*], for the simplest one-dimensional classification, when we know only one photometric parameter for the star that has to be classified, and one physical parameter (the effective temperature). He modified them for GAIA and applied them to the photometric data, simulated for GAIA in Vilnius. The conclusion is that the Minimum Distance Method provides better parametrization accuracy and should be preferable for GAIA data.

V. Malyuto and T. Shvelidze (Abastumani Observatory, Georgia) participated also in a so called GAIA blind testing procedure. Simulated photometric data for standard and programme stars were distributed by the organizers of the procedure; using these data and available classification methods, the participants had to classify programme stars, with unknown physical parameters. Two samples of classified programme stars (one in the 1X and other in the 2F photometric systems) have been sent to the organizers of the testing.

In the framework of Dresden (Germany) high precision position determination programme for minor planets V. Malyuto participates in calculations of colour refraction corrections necessary for accurate astrometry. Different sources of necessary colour information were analysed. It was found that spectral types provide slightly better positional accuracy than the BV photometry. The results have been published in Astronomische Nachrichten.

Tools

Statistics

An important problem in the study of the spatial distribution of galaxies is the estimation of the continuous density distribution on the basis of galaxy position data, a point process. The usual procedure is smoothing by a Gaussian or an Epanechikov kernel; the smoothing radius is an extra parameter of the procedure. E. Saar, together with V. Martínez (València University Observatory, Spain), J.L. Starck (CEA-Saclay, France) and D.L. Donoho (Stanford University, USA) developed a density estimation technique based on wavelets that includes automatically all spatial scales. In order to compare and characterize different densities, they used Minkowski functionals, especially the topological, Euler characteristic. During the work they found several unexpected effects (phantom functionals caused by numerical noise, possible fractality of the Euler characteristic) and developed an idea of multiresolution mathematical morphology. The work is in the final stages.

Together with R. Stoica (University of Jame I, Castellon, Spain) and V. Martínez E. Saar developed a technique for description of the filamentary structure of galaxy samples, using marked point processes. Marked point processes are used in statistics to describe geographical databases (GIS); they seem to be promising also for describing the large-scale spatial structure of galaxy distributions. The calculations for the first, two-dimensional case are completed, the results are good (see Fig. [*]), and the paper is in the works.

Figure: A two-dimensional galaxy distribution (dots) and the automatically generated filament system (lines), based on the galaxy distribution.

Dynamics of dark matter and $N$-body models

E. Saar wrote additional modules for the free $N$-body code MLAPM, which allow to model data for observational light-cone catalogues. The usual $N$-body models describe the dynamical state of a region of a universe at a given moment of time. As the speed of light is finite, we can never observe such a snapshot of the universe. For nearby regions snapshots do not differ much from observations, but for deeper samples the differences are considerable. Up to now only two-three light-cone models have been calculated, all these using large parallel computers. The new modules allow us to model expected observational light-cones also on usual workstations. The light-cones can have any realistic geometry, as, e.g., the Sloan survey slices, or deep pencil beams. We plan to use the package first for studying and explaining the environmental dependence of the properties of galaxy clusters and groups.

I. Pärn, a student of Tartu University, studied for her bachelor thesis (supervisor E. Saar) the form of galaxy clusters in the observable velocity space, using $N$-body models. In this space the distances of cluster galaxies are severely distorted by their radial velocities towards the observer. Although cluster modelling has a long history, such models have not been studied at all. These models can be directly compared with the observed fingers-of-God. This work continues, searching for scaling relations, which describe cluster fingers. Applications of such models are various, including checking cluster structure, determination of the parameters of cosmological models, and providing templates for automated cluster detection procedures.

M. Gramann, together with her Ph.D. student G. Hütsi from Tartu University, compared different $N$-body methods used for modelling the distribution of dark matter in the universe. They studied the influence of the total number of particles and the mesh resolution for the PM (particle-mesh) method, comparing the density and velocity fields for different parameter values. They found that mass resolution (the number of particles) influences seriously the results of the $N$-body simulations.

They plan to continue these studies. G. Hütsi is working presently in the Max-Planck Institute for Astrophysics, Germany, and participates in the Planck project for the measurement of the cosmic microwave background; his supervisor is Rashid Sunyaev. G. Hütsi has to analyse the Sunyaev-Zeldovich (SZ) effect in different galaxy clusters. This demands accurate models of dark matter haloes of clusters.

M. Einasto continued generating computer animations, in order to visualize the large-scale structure of the universe, both for numerical models and for observational data. These animations can be seen as online appendices to the papers of the cosmology group at Tartu Observatory web pages and at the web pages of EDP Sciences (Astronomy & Astrophysics). We have also used these animations for our talks and popular lectures.

Dynamics of galaxies

P. Tenjes and E. Tempel, a master student of Tartu University, started constructing detailed hydrodynamical models of nearby galaxies. The models are based on the Jeans equations; considerable attention is devoted to solving these equations for regions far from the galactic plane. The problem of closure was solved by using the Kusmin theory of the third integral. As it is possible to obtain from observations detailed information on velocity dispersions of galaxies, the Jeans equations are solved for these dispersions, and relations between model and observed dispersions have been found. In general, the observed dispersion is a sum of the model dispersion components, projected to the line-of-sight. The model has been realized as a Fortran program, that calculates velocity dispersions and compares the results with observational data. As the program has to calculate high-dimensional integrals, it is rather slow. Up to now mainly test runs have been carried out to study, how the variation of different parameters influences the results. The tests have been successful; the next steps will be the improvement of the model and the speed-up of the program.

International projects

The cosmology group of Tartu Observatory is participating in several international projects. They have also been active in preparation of new projects; we describe this work below.

Structure, chemical composition and evolution of stars

Late-type stars

The observing programme of the post-AGB stars after the final helium-shell flash was continued by T. Kipper and V.G. Klochkova (Special Astrophysical Observatory, Russia). This year the spectra of nonvariable hydrogen deficient carbon stars (HdC) were observed.

On January 6, 2002 a new highly peculiar variable star V838 Mon was discovered. Among the first suggestions about its nature the final helium flash was also considered but quite soon it turned out to be not applicable. Our first high disperson spectra were obtained less than a month after the discovery just before the light maximum was reached. At the same time the regular medium resolution spectral observations were started at Tartu Observatory. Altogether more than 70 spectrograms were obtained (K. Annuk, L. Leedjärv, A. Puss, A. Hirv). These observations were described in the last years Annual Report. This year we analysed these data together with the high resolution spectra obtained with the Ondrejov 2 m telescope (P. Skoda and M. Slechta).

Our spectra obtained only one day before the second and brightest light maximum showed numerous metallic lines with P Cygni profiles. Four absorption components with velocities from $-55$ to $-270$ km s$^{-1}$ were found. Two emission components allowed to determine the systemic velocity $+59$ km s$^{-1}$. The Na I D lines also showed P Cygni profiles with three strong interstellar (IS) components. From their equvalent widths we found the reddening distance to the object to be at least 3 kpc. By comparing the radial velocities of these IS lines with the H I clouds velocities and supposing that these are caused by Galaxy rotation we estimated the kinematic distance to the object not less than 4 kpc. V838 Mon showed also a light echo. The latest distance estimates using the light echo expansion gave the distances between 3 and 7 kpc in accordance with our results.

Figure: The temporal change of the V838 Mon spectrum in the vicinity of the H$\alpha$ line. The vertical shift of the spectra is proportional to time. The time is indicated as JD - 2 452 000. Not all the obtained spectra are depicted here in order to avoid crowding.

I. Kolka performed the analysis of spectral time series of the peculiar variable V838 Mon. Its spectral evolution after the second outburst is best characterized by the continuous decrease of excitation state, with a temporary increase during the third light maximum. During approximately 20 days between the second and the third light maxima, a faint but definitely measurable He I emission line at $\lambda 5876$ was present in the spectrum of V838 Mon, at systematically different radial velocity compared to the bulk of other emission lines. The origin of this He I line is still a question, it could form near another hotter star, a possible close binary component of the system. It should also be noted, that the spectral classification of V838 Mon based on bright supergiant standard stars has pointed to considerably higher effective temperature than was estimated earlier from photometric data.

Figure: The temporal change of H$\alpha$ intensity in V838 Mon spectrum starting with the second outburst. For comparison the schematic lightcurve in V is given.

We also estimated the chemical composition of V838 Mon using the March, 2002 spectra when the P Cygni emission components were significantly weakened. The abundances of most elements are slightly less than the solar ones, [Fe/H]=$-0.4\pm0.3$ with enhanced Li, Ba and La abundances. These abundances do not resemble the ones found in the "late He-flash" objects.

The absolute magnitude of V838 Mon peaked at $M_{\rm bol}= -9.6$. At the moment its outburst lacks explanation. The most promising scenario of merging of two main sequence stars of masses 1.5 and about 0.5 $M_{\odot}$ was proposed by R. Tylenda and N. Soker.

Early-type stars

T. Nugis and H. Lamers (Utrecht University, The Netherlands) studied the self-regulation mechanisms of intensive radiatively-driven optically thick winds of Wolf-Rayet (WR) stars. In recent works they found that the mass loss of WR stars is formed in very deep layers and that their critical wind surfaces (where the wind velocity becomes equal to the local sound speed) are located in the optically thick (for continuum) zone. Further investigation has led to the conclusion that very efficient self-regulation mechanism(s) is (are) needed for a WR star to stay in the optically thick wind mode during the evolution. This follows from the fact that the masses of WR stars decrease some tens of times during the evolution causing the big change in the value of critical opacity ( $\chi_{\rm cr} \approx 4 \pi c G M / L$, where $M$ is stellar mass and $L$ stellar luminosity).

The sonic points of hot WNE stars ought to be located in that part of the star where the local temperature is about 150 000 - 170 000 K, i.e. in the region where the wind matter has its opacity maximum (due to the contribution of iron lines). The estimates show that for WNE stars with masses $M \approx 30-50~M_{\odot}$ the Rosseland-mean (OPAL) opacity maximum value at about $T \approx 160\,000$ K is somewhat higher than the critical opacity, but for the small-mass WNE stars with masses $M \approx 3-5 ~M_{\odot}$ the Rosseland-mean opacity at $T \approx 160\,000$ K is much smaller (3-10 times) from the critical opacity. T. Nugis and H. Lamers found that some extra enhancement of the opacity above that of the Rosseland-mean value can be caused by the expansion (due to the presence of velocity gradients), similarly to the classical CAK-mechanism in the optically thin OB-star winds. The increased opacity in the dense parts of the wind makes them in many cases convectionally unstable. Convection and extra enhancement of the opacity due to the expansion near the sonic point serve as an efficient self-regulation mechanisms for WNE optically thick winds.

T. Nugis, A. Niedzielski, K. Czart, K. Annuk and A. Hirv completed the spectral observations in the mid-IR range with the Tartu Observatory 1.5 m telescope (northern stars) and with the Radcliffe 1.9 m telescope of SAAO (South Africa) (southern stars) and started to reduce the observational data with a purpose to compose the Atlas of mid-IR spectra of WR stars and to determine some important WR parameters by the use of these new observations.

In 2003 continuing spectral and photometric observations were performed on hypergiants HR 8752, $\rho$ Cas and Cyg OB2 No 12 (T. Eenmäe, T. Tuvikene, A. Puss, A. Hirv). I. Kolka collaborated with C. de Jager and H. Nieuwenhuijzen from The Netherlands to investigate the real-time evolution of HR 8752 in the HR-diagram.

Formation of spectra in atmospheres of hot stars and stellar wind

A new method is elaborated by A. Sapar and R. Poolamäe, which allows by the use of simple algorithms to compute stellar atmospheres of hot stars. The crucial estimate of the quality of the modelling is that the iteration process converges rapidly to constant flux throughout the atmosphere. Thus, the resulting run of the temperature and of the gas pressure found corresponds well to the input physics. The elaborated software was applied for modelling of stellar atmospheres and computation of stellar spectra for A, B and O type stars. The modelling has been realized as generalization of the software SMART, originally composed for computation of high dispersion model stellar spectra. The computer code enables also to study different physical processes in stellar atmospheres and has been applied for such studies. In addition to above mentioned FORTRAN code SMART, R. Poolamäe has started to elaborate a new C++ code for modernization of computer language used in computations of stellar model spectra. As a starting point he used the code SPECTRUM by R.O. Gray, formulated on the computer language C. Adequate modelling of stellar spectra must be based on a very wide spectral region. The reasonable spectral interval in the modelling stretches from 20 to 3000 nanometers, i.e. from the extreme vacuum ultraviolet to the infrared radiation.

By the use of elaborated software a set of model atmospheres and corresponding stellar spectra was computed for O, B and A type stars. The software enables also to compute stellar spectra of rotating stars, limb darkening of stellar disc and the radiative accelerations for moving clumps in stellar atmospheres. The generalization of the code for computations of stellar spectra for NLTE situation is in the elaboration stage. Radiative transfer in the stellar wind was studied by L. Sapar, A. Sapar and R. Poolamäe. A new aspect was to derive formulae for a case if there is supersonic turbulence in the spherically-symmetric stellar wind. The formulae found describe partial redistribution of frequencies in the spectral line and the prevailing backscattering due to non-thermal contribution of turbulence motions. The mechanism enables to explain and to compute wide slanting slopes in the blue wing of P Cygni type spectral line profiles and corresponding additional emission features in the red wing of the spectral lines.

Element diffusion in the atmospheres of chemically peculiar (CP) stars.

A. Sapar ja A. Aret continued the study of diffusion segregation of chemical elements and their isotopes in the quiescent chemically peculiar stellar atmospheres. As a new aspect the evolutionary formation of vertical distribution of chemical elements, especially of Hg in the MnHg type stellar atmospheres, was studied and the spectral lines of Hg II were added to the input physics data. Also the more elaborated treatment of the particle collision processes, which are responsible for the efficiency of the diffusion phenomena, has been applied. The elaborated computer code SMART was improved and applied to study the evolutionary changes of isotopes of Hg. The results show the process of diffusion segregation of Hg isotopes in detail. As expected, the light-induced drift plays the leading role in the process. Depending on the asymmetry of radiation flux in spectral lines the drift can be directed upwards or downwards, giving rise to levitation or sedimentation of different isotopes. For heavy elements their lighter isotopes sink and the higher isotopes rise. At the final stage of evolution only strong overabundance of the single, namely the heaviest isotope of the chemical element studied remains in the atmosphere. The light-induced drift appears to be the only physical process which enables to explain the isotope anomalies in the chemically peculiar stellar atmospheres.

Symbiotic stars and related objects

Spectroscopic monitoring of selected symbiotic stars and related objects was continued with the help of the 1.5 m telescope (K. Annuk, L. Leedjärv, A. Puss and Ph.D. students M. Burmeister, T. Eenmäe, A. Hirv). Although the relatively bright objects (e.g. CH Cyg, AG Dra, EG And etc.) which are accessible to our telescope, are intensively observed in many other observatories, there are rarely such long-term homogeneous time series of spectroscopic data available for them, like those we have obtained in Tartu Observatory. In 2003, the results of the six-year monitoring of AG Dra were accepted for publication in Astronomy & Astrophysics. Among the main results were: (i) finding a clear correlation between the $U$ magnitude and the intensity of the emission lines; (ii) detecting a possible period of about 390 days in the variations of the emission lines; (iii) a conclusion that large scale cool outbursts of AG Dra (which repeat at about 13-15 years interval) are followed by smaller scale hot outburst(s) a few years later. The latter conclusion was confirmed after submitting the paper, when an outburst of AG Dra started in September 2003, bearing characteristic features of hot outbursts.

Detailed analysis of the spectra of another symbiotic star, CH Cyg, was started by M. Burmeister under supervision of . Both AG Dra and CH Cyg are studied in close collaboration with M. Miko\lajewski, T. Tomov, J. Osiwa\la, C. Ga\lan and others from Torun, Poland.

L. Leedjärv continued studies of characteristics of symbiotic stars which have ejected collimated high-velocity bipolar jets. The preliminary conclusion that those stars tend to contain hot components of low luminosity, was put in doubt with discovery of jets in classical symbiotic stars AG Dra and Z And by Miko\lajewska and Brocksopp, respectively.

Pre-cataclysmic close binaries

I. Pustylnik in cooperation with J. Kubát and J. Krticka from Ondrejov observatory (Czech Republic) elaborated the model of radiation-triggered coronal wind to elucidate the mechanism of the disc formation present in late type B stars, both in single stars and in binary systems. The basic element of the new model is the heating of the layers just above the photosphere in B4-B5 stars up to the temperatures of $10^{7} $K. One of the interesting features of the model following from the calculations made for three-component stellar wind lies in decoupling of passive plasma component in the layers where considerable adiabatic heating occurs. This circumstance can be used as an instrument in explaining the formation of accretion discs in these stars, whereas high temperature regions can be the site of X-ray emission often observed in relatively cool B type stars.

V.-V. Pustynski and I. Pustylnik continued their studies of physical processes in irradiated atmospheres of pre-cataclysmic binary systems (PCB). The software package compiled by V.-V. Pustynski to model the light curves of PCB was supplemented by a unit enabling to take into account in addition to irradiation effects also the mutual eclipses. The advantage of the elaborated model lies in direct modelling of irradiated emergent radiation angular distribution without necessity to introduce an arbitrary degree of limb darkening, assumed in conventional models. Since the size of the hot subdwarf companion is only about 0.1-0.2 solar radii, analysis of the light changes during the transit of the hot subdwarf projected upon the disc of the cool irradiated companion can provide a detailed information about the distribution of the irradiated flux over the bright hemisphere of the companion. The model light curves have been compared with the observed light curves of two eclipsing PCB systems UU Sge and V477 Lyr. In both binaries hot subdwarf companions are among the hottest ones in PCB systems suggesting that they have very recently emerged from the common envelope stage. The comparison of the model with the observed light curves indicates that in the case of V477 Lyr the hot subdwarf companion is even hotter than it followed from previous models, namely its effective temperature $T_{\rm eff}$ must be $T_{\rm eff} \geq 90\,000$ K.

GAIA mission

The local database on spectral energy distributions of emission line stars was enlarged with data on 7 representative Herbig Ae/Be (HAeBe) stars. To obtain relative fluxes with spectral resolution of 4 Å observations on the 1.5 m telescope of Tartu Observatory were performed by A. Hirv and T. Eenmäe. Using this database a set of selected colour indices in 1X and 2F photometric systems proposed for GAIA was computed. Both systems are capable to distinguish emission line Be and HAeBe stars from normal B and A stars if colour indices incorporating the Balmer jump or the region around H$\alpha$ line are used. The possibility to segregate Be and HAeBe stars on the basis of 1X or 2F colours is not fixed yet. I. Kolka made a report on these results at the meeting of photometry working group of GAIA in Leiden in October 2003. In November 2003 this subject was discussed at the meeting of scientific council of Tartu Observatory.

Time and frequency analysis of astronomical phenomena

J. Pelt proceeded with investigations in the field of astronomical time series analysis. A new version of the well known program ISDA (J. Pelt, Irregularly Spaced Data Analysis, Helsinki University Press, 1992) is nearly ready for public use. The program implements high precision algorithms for spectral and correlation analysis of irregularly measured data. There are also new visualization facilities and capability to handle large data sets using database techniques.

Preliminary version of the program is already in use in the field of chemical analysis (Tallinn Technical University), in the context of sunspot statistics (with Ilkka Tuominen, Oulu University) and in spectral variability analysis of magnetically active stars (collaboration with Svetlana Berdyugina, ETH, Zürich, Switzerland).

Radiative transfer

I. Vurm and T. Viik calculated the emissive power and radiative flux in a two-dimensional, absorbing-emitting, finite atmosphere subjected to a strip of collimated incident radiation. In order to find a solution to this problem they used the solution to the similar problem with collimated cosine varying incident radiation which had been found in their previous papers by approximating the kernel of the integral equation for the emissive power by a sum of exponents. This allowed to find all the parameters of the radiation field, both external and internal. The main point of the approach, already used by Breig and Crosbie, consisted of expressing the solution for the case on hand as a superposition of solutions to the case of collimated cosine varying incidence. This brought along infinite integrals which were converted to an alternating series of finite integrals while the integration was simplified by separating an integrable part of the integrand. For speeding up the convergence of these series the authors used the Euler transformation. They analysed the obtained solutions and gave some illustrations.

Optical remote sensing of environment in Estonia and Baltic region

Solar UV radiation and atmospheric ozone

Regular measurements of the solar erythemal UV radiation with a Scintec UV SET sensor, with a Kipp & Zonen narrowband UV-B sensor and with a UV-A sensor based on a photodiode and filters were continued (U. Veismann, A. Kallis, E.-M. Maasik). The UV-A and UV-B sensors were prepared for the regular measurements. A fiber optic spectrometer Avantes AvaSpec-256 (240-440 nm, 0.8 nm resolution) was purchased in October 2003. Preliminary work connected with automatic data recording, calibration and data processing was started (U. Veismann, S. Lätt, I. Ansko).

Establishing UV climatology at Tartu Observatory site was continued (K. Eerme, U. Veismann, R. Koppel). A local database containing the proxy and necessary auxiliary data for estimates of the erythemally weighted UV doses for the years 1955-2002 was compiled (K. Eerme, A. Jõeveer). The integrated spring (since the vernal equinox to the summer solstice) and summer (since the summer solstice to the autumnal equinox) erythemal doses have been estimated separately as well as the doses for May-June and July-August. The spring and summer erythemal doses within the period 1955-2002 were not mutually correlated. The probability density distribution of the spring dose was close to the normal distribution hinting to the random process like year-to-year changes in spring cloudiness. That of the summer total doses has been distributed rather bimodally. The appearance of cloudy and fine weather summers manifests a quasiperiodic cyclicity.

Correlative relationships between TOMS retrieved total ozone and atmospheric characteristics (tropopause height and temperature, geopotential heights of the pressure levels 500 hPa, 300 hPa, 200 hPa) recorded at the Tallinn-Harku aerological station $(59^\circ$26'N, $19^\circ$45'E) have been studied for 1979-2002. The sounding data for 1997-1998 are unfortunately missing. The correlation between day-to-day changes (small changes excluded) in total ozone and the atmospheric characteristics has been higher during the warm period of the year. The highest correlation (coefficient values $-0.87$ in summer, $-0.83$ in winter) was found between total ozone and the tropopause height. The largest differences in summer and winter were recorded in the correlations between total ozone and tropopause temperature. At the beginning of the Nimbus-7 TOMS ozone record the correlation differences between the warm and cold season were smaller than at the end of the Nimbus-7 mission. On the monthly and bi-monthly level the linear correlation between the daily values of total ozone and tropopause height manifested high variance from $-0.83$ to less than $-0.10$. As compared to the geopotential heights and tropopause temperature, exhibiting on an average the highest values in July and the lowest in January-February, the annual cycle of tropopause height was in lag, presenting the highest value in August and the lowest in March. Systematic trends in atmospheric characteristics during 1979-1996 have been most evident in September-November ($+28$ m/decade in 500 hPa height, $+300$ m/decade in tropopause height, $-2.2$ K/decade in tropopause temperature), they have been about two times less extent in summer and spring. In December-February no reliable trend was detected. Since 1999 the trends have been rather opposite to those in 1979-1996.

Climate studies

In order to calculate the optical thickness of atmospheric aerosol from the measurement data of integral solar radiation, the extinction of radiation by ideal atmosphere and water vapour must be known. The former is easy to calculate, while for assessment the role of the latter factor several models exist. V. Russak has used the models by S.V. Zvereva and C. Gueymard dealing with the atmospheric optical mass $m$ = 2. The comparison of these models has shown that the values of optical thickness of water vapour estimated by Zvereva's model are systematically lower than those by the model of Gueymard. The difference depends on the water vapour content in the atmosphere and reaches $30\%$ in Estonia in summer conditions. Using the data of solar radiation and air water vapour pressure, measured at Tartu-Tõravere Meteorological Station (1955-2002), the mean annual courses of the aerosol optical thickness of water vapour and atmospheric aerosol as well as the time series of their mean annual values were calculated by the Gueymard method. The water vapour optical thickness was relatively stable during the period under study, the aerosol optical thickness, however, varied within great limits with an obvious increasing trend up to the middle of the 1980s. The following decrease in atmospheric aerosol loading in Estonia during the last 15-20 years is probably caused by two main factors: the reduction of the emission of air pollutants in Western and Central Europe and drastic decline and subsequent restructuring of economy in Estonia as well as in other previous so-called socialist countries at the beginning of the 1990s. At present the mean annual aerosol optical thickness is comparable with that of water vapour in Estonia. Great volcanic eruptions (El Chichon, 1982 and Mt. Pinatubo, 1991) essentially increased the atmospheric aerosol loading (Fig. [*]).

Figure: Mean annual values of optical thickness of atmospheric aerosol (dashed line) and water vapour (continuous line) at Tõravere in the period 1955-2002, estimated by the Gueymard method.

The measurements of radiation balance components during half a century at Tartu-Tõravere and Tiirikoja have generated a database allowing to describe statistically reliably the radiation regime in Estonia. In the "Handbook of Estonian Solar Radiation Climate", compiled by V. Russak and A. Kallis, the mean values, variability and long-term courses of solar and infrared radiation as well as the factors influencing them (cloudiness, atmospheric transparency, sunshine duration) during the period 1955-2000 have been analysed. In addition, the conditions of UV-radiation (U. Veismann, K. Eerme, R. Koppel), photosynthetically active radiation and illumination as well as radiation regime on different oriented surfaces are considered. In appendices a large amount of measurement data is presented.

O. Kärner analysed several temperature series recorded by different meteorological stations in order to study their long-range correlations and anti-persistence. The work is important for determining contemporary climate variability in different places over the Earth.

Remote sensing of vegetation and reflectance spectra of forest understorey

T. Nilson and A. Kuusk in collaboration with P. Stenberg and M. Rautiainen (University of Helsinki) estimated the needle area of Scots pine-dominated forest stands in Finland by inverting the forest reflectance model developed at Tartu Observatory. As input information, an atmospherically corrected Landsat-7 ETM image, data from the respective forestry database and results of ground-based measurements by means of plant canopy analysers were used.

Using the library of reflectance spectra of ground vegetation for Estonian forests compiled in Tartu Observatory, A. Kuusk, M. Lang and T. Nilson tested the two-layer canopy reflectance model developed by A. Kuusk. The values of input parameters of this model were estimated, so the model can be used as a submodel of the forest reflectance model also developed at Tartu Observatory. By making use of the Kuusk-Nilson forest reflectance model, T. Nilson, A. Kuusk, M. Lang and T. Lükk carried out model calculations to establish relations between the contents of chlorophyll and water in tree leaves/needles and spectral reflectance factors of tree stands. It was found that the indices suggested in literature and defined on the basis of reflectance measurements outside the respective absorption band and on the edge of the band can be used to estimate the chlorophyll and water contents in tree leaves from remote sensing spectral measurements. The indices studied were the chlorophyll normalized difference $(R750-R705)/(R750+R705)$ and simple ratio $R750/R705$ indices and the similar water indices - normalized difference $(R860-R1240)/(R860+R1240)$ and simple ratio $R860/R1240$ or $R900/R970$. However, one has to bear in mind that the uncertainty (e.g. 30%) in most important stand variables (leaf area index, canopy closure, understorey leaf area, etc.) can introduce a similar uncertainty (30%) in the estimate of leaf chlorophyll or water content.

By means of another model simulation effort, the seasonal course of reflectance for birch-dominated stands was derived in the spectral regions of green, red, near infrared and middle infrared. The results agree qualitatively well with the seasonal courses of reflectance as determined from different atmospherically corrected Landsat and SPOT images for a set of birch-dominated forests in Järvselja region. T. Nilson and A. Kuusk elaborated a new algorithm to estimate the leaf area index of forest canopies from the results of measurements of the angular distribution of gap fraction. The algorithm is mainly oriented towards the use of plant canopy analysers LAI-2000. As novel features, the algorithm enables one to correct for the role of tree trunks in the gap fraction data and to regularize the noisy gap fraction data caused by insufficient spatial sampling before applying the inversion.

T. Nilson together with P. Stenberg (University of Helsinki), H. Smolander and P. Voipio (Finnish Forest Research Institute) performed an analysis of change in the angular distribution of gaps in a Scots pine stand, subjected to an experimental removal of branches and trees. The measured and predicted by Nilson's algorithm gap fractions and their changes due to the removal of branches and trees agreed well.

M. Lang, T. Lükk, H. Böttcher and T. Nilson performed two series (midsummer and late autumn without leaves on deciduous trees) of gap fraction measurements on the test site of the international VALERI (VAlidation of Land European Remote sensing Instruments) programme in Järvselja. The canopy analysers LAI-2000 were used and hemispheric photos of the upper and lower hemisphere taken.

M. Pehk elaborated an experimental copy of the field spectrometer for the reflectance measurements in the middle infrared region of the spectrum.

The CCD-radiometer of 170$^\circ$ field-of-view was modified for the measurements of upward radiation fluxes (A. Kuusk and ). The fine angular resolution of reflected radiation in energy forest plantation at Tartu Observatory was studied in red (680 nm) and near infrared (800 nm) spectral regions.

A. Kuusk studied the leaf area index of the test site of US Department of Agriculture Beltsville Agricultural Research Center in collaboration with H. Fang and S. Liang (Maryland University, USA) using the homogeneous canopy reflectance models developed at Tartu Observatory and satellite information (Landsat-7 ETM).

Satellite Landsat medium resolution scanner Thematic Mapper images were used to map forest clearcut areas in the counties and communes of Estonia. The satellite image dataset covers a time interval from 1987 till 2003. Data from forestry databases were used by U. Peterson to verify the results. Digital soil map was used in post-classification refinement of clearcut distribution into respective soil types.

Energy forest

The grey alder and willow plantations founded in 2000-2001 stood successfully the dry summer 2002 and hard winter following. In 2003 the development of the plantations was considerable. At the end of the vegetation period the height of plants, their architecture, size and shape of the leaves in the alder plantation was much more variable than in willow plantation. For that reason the amount of the biometrical measurements was increased considerably to get trustworthy results. In the willow plantations at Tõravere, Saare and Kambja the biometrical measurements were carried out only periodically to estimate production of the biomass and to check the former results. The measurements of the radiation regime were carried out only in the alder plantation. Due to the variability of the plantation it was needed to increase the number of the measurements to get the dependence on the azimuth of the sun.

The detailed biometrical measurements in the alder plantation were carried out at four levels (the leaf, branch, plant and plantation levels). Trees of different heights were chosen as test objects, and a maximum number of parameters was determined without cutting the plants. At leaf level, the leaf length $a$, width $b$ and area $S_{\mathrm L}$ were determined. All these parameters vary to great extent, the linear size of the leaves up to 20 times, the distribution histogram is close to the normal distribution. The area of the leaves varies up to 200 times, the distribution can be approximated with the lognormal one. At branch level, the branch length L, branch inclination angle j, the azimuthal orientation of branches, and the distribution of leaf area along the branch were measured. Branch length varies largely, the best fit is the lognormal distribution. The inclination angles are between 15 and 85 degrees, the normal distribution fits the measured values best. The distribution of the leaf area along the branch is not regular, the large and small leaves may be located alternately, only total leaf area is in correlation with the branch length.

The most important problem at plant level is the distribution of leaf area with height, its estimate is based on the normalized vertical leaf area distribution. The problem is how stable is the normalized distribution for different plants. The alder plantation is quite heterogeneous, for that reason the assessment of the leaf area vertical distribution based only on the height of plants is not appropriate. It is possible only by using the leaf area distribution along the branch, the correlation between branch length and total leaf area and taking into account horizontal reach of branches. At plantation level the height of plants, the orientation of the leaves and estimated vertical distribution of leaf area and leaf area index were measured. The height of plants was measured over all the plantation and more in detail at the radiation measurement system. The variation of the height of the plants was considerable, up to 10 times. The yearly increase was 2 meters at maximum, and the height of most vigorous plants achieved 4 meters.

Downward and upward fluxes of integral solar radiation as well as photosynthetically active radiation were measured in the alder plantation at the height of 43, 147, 221 and 297 cm inside the canopy and at 504 cm above it. The routine radiation measurements carried out at Tartu-Tõravere Meteorological Station were used as reference data. Extended radiation measurements took place in July in collaboration with A. Kuusk and M. Mõttus: spectral and angular characteristics of the radiation field inside the canopy were determined using the CCD-radiometer and hand-held spectrophotometer. Spectral scattering indicatrices of the leaves were measured in the laboratory at four wavelength in blue, green, red and near infrared spectral region. The indicatrices are quite similar to those of the Lambertian surface, obviously due to rough structure of the leaf surface. The processing and analysis of collected data is in progress. The vertical profiles of the radiation fluxes inside the canopy are calculated. The alder plantation is more transparent than the willow coppice and the absorption of the photosynthetically active radiation occurs more uniformly inside the canopy. The statistical model to describe radiation regime inside the willow plantation seems to be appropriate for the alder as well, the analysis of the data obtained in 2003 should give final clarity in this problem.

Two radiation transfer models are elaborated to describe relationship between plantation biometrical structure and parameters of the radiation field inside it: a simple model using discrete ordinates and a model based on the simulation of the photons path. The last one needs detailed biometrical information about the canopy, a "statistically average plant" is designed on the basis of it and, after that, the "average plants" are patched up as a model of the plantation. The spectral and angular characteristics of the incoming radiation are taken from literature, data of NASA AERONET programme measurements at Tõravere are also used. Optical properties of the plants are combined from published data and our laboratory measurements. The models are rough and approximate yet, the improvement and check is in progress.

Publications

Books

Eesti kiirguskliima teatmik. Koost. V. Russak ja A. Kallis. Tallinn, 384 lk., 2003.

Papers in scientific journals and books

Astronomy

Dubkova D.N., Kudryavtseva N.A., Hirv A.: The Light Curve of the New Cataclysmic Variable SDSS J015543.40+002807.2. Inf. Bull. Variable Stars 5389, 1-3, 2003.

Eerik H., Tenjes P.: Metallicity Distributions of Globular Cluster Systems in Galaxies. Astronomische Nachrichten 324, 242-249, 2003.

Einasto J., Hütsi G., Einasto M., Saar E., Tucker D.L., Müller V., Heinämäki P.: Clusters and Superclusters in the Sloan Digital Sky Survey. Astron. Astrophys. 405, 425-443, 2003.

Einasto J., Einasto M., Hütsi G., Saar E., Tucker D.L., Tago E., ., Heinämäki P., Allam S.S.: Clusters and Superclusters in the Las Campanas Redshift Survey. Astron. Astrophys. 410, 425-443, 2003.

Einasto M., Einasto J., Müller V., Heinämäki P., Tucker D.L.: Environmental Enhancement of Loose Groups around Rich Clusters of Galaxies. Astron. Astrophys. 401, 851-862, 2003.

Einasto M., Jaaniste J., Einasto J., Heinämäki P., Müller V., Tucker D.L.: Las Campanas Loose Groups in the Supercluster-Void Network. Astron. Astrophys. 405, 821-831, 2003.

Ergma E., Sarna M.J.: Eclipsing Binary Millisecond Pulsar PSR J1740-53 - Evolutionary Considerations and Observational Test. Astron. Astrophys. 399, 237-241, 2003.

Heinämäki P., Einasto J., Einasto M., Saar E., Tucker D.L. .: The Mass Function of the Las Campanas Loose Groups of Galaxies. Astron. Astrophys. 397, 63-70, 2003.

Langhans R., Malyuto V., Potthoff H.: Calculated Atmospheric Color Refraction and Observed Stellar Positions. Astronomische Nachrichten 324, 454-459, 2003.

Malyuto V.: The Minimum Distance Method of Classification Using Linear Interpolation with its Applications to Simulated GAIA Photometry. The Journal of Astronomical Data 9, 8, 2003.

Marchenko S.V., Moffat A.F.J., Ballereau D., Chauville J., Zorec J., Hill G.M., Annuk K., Corral L.J., Demersi H., Eenens P.R.J., Panov K.P., Seggewiss W., Thomson J.R., Villar-Sbaffi A.: The Unusual 2001 Periastron Passage in the "Clockwork" Colliding-Wind Binary WR140. Astrophys. J. 596, 1295-1304, 2003.

Pelt J.: Astronomical Time Series Analysis, Lecture Notes, Oulu, 1-157, 2003 (www.aai.ee/$\sim$pelt).

Pustylnik I.: International Conference "Struve Arc 150". Astron. Astrophys. Transactions 22, 363-364, 2003.

Pustylnik I.: 10th SEAC Annual Meeting. Astron. Astrophys. Transactions 22, 365-367, 2003.

Pustylnik I.: Obituary: P. Kalv (1934-2002). Astron. Astrophys. Transactions 22, 369-370, 2003.

Sapar A., Sapar L., Poolamäe R.: Analytical Solutions for the Saturated P Cygni Type Profiles II: General Case. Astrophys. Space Sci. 286, 333-345, 2003.

Suhhonenko I., Gramann M.: The rms Peculiar Velocity of Galaxy Clusters for Different Cluster Masses and Radii. Mon. Not. Royal Astr. Soc. 339, 271-279, 2003.

Tamm A., Tenjes P.: Structure and Mass Distribution of Spiral Galaxies at Intermediate Redshifts. Astron. Astrophys. 403, 529-536, 2003.

Temporin S., Ciroi S., Rafanelli P., Radovich M., Vennik J., Richter G.M., Birkle K.: Analysis of the Interaction Effects in the Southern Galaxy Pair Tol 1238-364 and ESO 381-G009. Astrophys. J. Suppl. Ser. 148, 353-382, 2003.

Viik T., McCormick N.J.: Numerical Test of an Inverse Polarized Radiative Transfer Algorithm. Journal of Quant. Spectr. Rad. Transfer 78, 235-241, 2003.

Vurm I., Viik T.: Emissive Power and Flux in an Atmosphere Subjected to a Finite Strip of Radiation. Proceedings of Estonian Acad. Sci. Phys. Math. Ser. 52, 207-220, 2003.

Geophysics

Eerme K., Veismann U., Koppel R.: Erüteemsete ultraviolettkiirguse dooside tagasivaatav hindamine. Publ. Inst. Geographici Universitatis Tartuensis 93, 295-307, 2003.

Fang H., Liang S., Kuusk A.: Retrieving Leaf Area Index Using a Genetic Algorithm With a Canopy Radiative Transfer Model. Remote Sensing of Environment 85, 257-270, 2003.

Kärner O.: Klimatoloogia - aritmeetiline rahvaluule või ratsionaalne andmetöötlus. Publ. Inst. Geographici Universitatis Tartuensis 93, 9-23, 2003.

Mõttus M.: Measurement and Modelling of the Vertical Distribution of Sunflecks, Penumbra and Umbra in Willow Coppice. Agricultural and Forest Meteorology 121, 79-91, 2003.

Nilson T., Kuusk A., Lang M., Lükk T.: Forest Reflectance Modeling: Theoretical Aspects and Applications. Ambio 33(8), 534-540, 2003.

Rautiainen M., Stenberg P., Nilson T., Kuusk A., Smolander H.: Application of a Forest Reflectance Model in Estimating Leaf Area of Scots Pine Stands Using Landsat-7 ETM Reflectance Data. Canadian Journal of Remote Sensing 29, 314-323, 2003.

Russak V., Niklus I.: Päikesekiirguse vootiheduste suhe kui atmosfääri läbipaistvuse indikaator. Publ. Inst. Geographici Universitatis Tartuensis 93, 288-294, 2003.

Stenberg P., Nilson T., Smolander H., Voipio P.: Gap Fraction Based Estimation of LAI in Scots Pine Stands Subjected to Experimental Removal of Branches and Stems. Canadian Journal of Remote Sensing 29, 363-370, 2003.

Conference papers

Astronomy

Aret A., Sapar A.: Light-Induced Drift in Atmospheres of CP Stars. In: IAU Symposium No. 210, eds. N.E. Piskunov, W.W. Weiss and D.F. Gray, CD-ROM, List B4, 7 p., 2003.

Boschetti C.S., Ciroi S., Funes J., Omizzolo A., Rafanelli P., Richter G.M., Rifatto A., Vennik J.: A Morphological Optical Survey of Nearby AGN. In: AGN Surveys. Proc. of the IAU Colloq. 184, eds. R.F. Green, E.Ye. Khachikian and D.B. Sanders, ASP Conf. Series 284, 89, 2002.

Kalberla P.M.W., Kerp J., Haud U.: The Velocity Dispersion of Galactic Dark Matter. In: Seeing Through the Dust: The Detection of H I and the Exploration of the ISM in Galaxies, eds. A.R. Taylor, T.L. Landecker and A.G. Willis, ASP Conf. Series 276, 453, 2002.

Kalv P., Harvig V., Aas T., Pustylnik I.: Dual-Star Photometer at the Tallinn Observatory. In: Proc. of the Conference "Stellar Photometry: Past, Present and Future", ed. V. Straizys, Baltic Astronomy 12, 639-641, 2003.

Leedjärv L.: Symbiotic Stars with High-Velocity Jets - in the Example of CH Cygni. In: Symbiotic Stars Probing Stellar Evolution, eds. R.L.M. Corradi, J. Miko\lajewska and T.J. Mahoney, ASP Conf. Series 303, 433-436, 2003.

Martínez V.J, Saar E.: Statistics of Galaxy Clustering. In: Statistical Challenges in Astronomy. Third Statistical Challenges in Modern Astronomy (SCMA III) Conference, eds. E.D. Feigelson and G.J. Babu, New York, Springer, 143-160, 2003.

Martínez V.J., Saar E.: Clustering Statistics in Cosmology. In: Astronomical Data Analysis II. Proceedings of the SPIE, Vol 4847, eds. J.-E. Starck and F. Murtagh, 86-100, 2002.

Niedzielski A., Nugis T.: Hydrogen-to-Helium Ratio in WR stars from GAIA Spectroscopy. In: GAIA Spectroscopy, Science and Technology, ed. U. Munari, ASP Conf. Series 298, 439-442, 2003.

Puss A., Leedjärv L.: Varuability of the H$\alpha$ Spectral Line in the Symbiotic-Like Binary Star AX Monocerotis. In: Symbiotic Stars Probing Stellar Evolution, eds. R.L.M. Corradi, J. Miko\lajewska and T.J. Mahoney, ASP Conf. Series 303, 159-162, 2003.

Pustylnik I.: The Role of Celestial Routes of Nocturnally Migrating Birds in the Calendrics and Cosmovisions of Ancient People. In: Proceedings of the Ninth Annual Meeting of the Society for European Astronomy in Culture (SEAC), "Calendars, Symbols, and Orientations: Legacies of Astronomy in Culture", Uppsala Astronomical Observatory, Report No. 59, Uppsala, 83-87, 2003.

Pustynski V.-V., Pustylnik I.: Modelling the Irradiated Atmospheres of Unevolved Companions in Precataclysmic Binaries (PCB). In: Proceedings of the NATO Advanced Research Workshop on White Dwarfs, NATO Science Series II: Mathematics, Physics and Chemistry, Vol. 105, eds. D. de Martino, R. Silvotti, J.-E. Solheim and R. Kalytis, Kluwer Academic Publishers, 345-346, 2003.

Potjomkina T.M., Obridko V.N., Lushnikova A.V., Pustylnik I., Chepurova V.M.: Astronomy of Ancient Civilizations. The International Conference of the Society for European Astronomy in Culture - SEAC, Moscow, 2000. In: Rossijskaja Arheologia 2, 182-191, 2003 (in Russian).

Sapar A., Poolamäe R.: ``SMART": A Compact and Handy FORTRAN Code for the Physics of Stellar Atmospheres. In: Stellar Atmosphere Modeling, eds. I. Hubeny, D. Mihalas and K. Werner, ASP Conf. Series 288, 95-98, 2003.

Sarna M.J., Ergma E.: Eclipsing Binary ms Pulsar PSR J1740-5340: pre-He White Dwarf+ms Pulsar System? In: Proceedings of the NATO Advanced Research Workshop on White Dwarfs, NATO Science Series II: Mathematics, Physics and Chemistry, Vol. 105, eds. D. de Martino, R. Silvotti, J.-E. Solheim and R. Kalytis, Kluwer Academic Publishers, 283-286, 2003.

Tuvikene T., Kolka I.: Experience in CCD Photometry at the Tartu Observatory. In: Proc. of the Conference "Stellar Photometry: Past, Present and Future", ed. V. Straizys, Baltic Astronomy 12, 647-648, 2003.

Viik T., McCormick N.J.: Numerical Test of an Inverse Polarized Radiative Transfer Algorithm. In: Abstracts of NATO Advanced Study Institute on Photopolarimetry in Remote Sensing, 101, 2003.

Geophysics

Kärner O., Karlsson G.-K.: Climate Monitoring SAF Cloud Products Feasibility Study in the Inner Arctic region. Part II: Evaluation of Variability in Radiation and Cloud Data. In: Visiting Scientist Report, SMHI, Norrköping, 1-50, 2003.

Mellikov E., Tomson T., Kallis A., Russak V.: Steady-State Variability of Solar Irradiance. In: ISES Solar World Congress 2003, June 14-19, Göteborg, Sweden, Abstracts, 247, 2003.

Mellikov E., Tomson T., Kallis A., Russak V.: Steady-State Variability of Solar Irradiance. In: ISES Solar World Congress 2003, June 14-19, Göteborg, Sweden, CD-ROM, 6 p., 2003.

Peterson U.: Changes in Estonian Agricultural Land Use in the 1990s. Measurement Results of Satellite Images. In: Õpetatud Eesti Seltsi Aastaraamat 1994-1999, eds. K. Grichin, T. Rosenberg and H. Valk, Tartu, 325-328, 2002.

Peterson U.: Forest Mapping for Eastern Baltic Region with Landsat Thematic Mapper Winter Images. In: Proceedings of a Conference "Research for Rural Development", Jelgava, Latvia, 21-24 May 2003, 189-192, 2003.

Seckmeyer G., Allaart M., Arola A., Bais A., Baumgartner D., Blumthaler M., Borkowski J., Brogniez C., Cabot T., Casiniere A., Edvardsen K., Engelsen O., Eerme K., Feister U., Ferraguto M., Gardiner B., Gillotay D., Glandorf M., Gonzi S., Groebner J., Heikkila A., Henriques D., Hout M., Janouch M., Kaurola J., Kift R., Kirsch P., Kjeldstad B., Krzyscin J., Kylling A., Lapeta B., Lenoble J., Litynska Z., Martin T., Masserot D., Meleti C., Norvang Nilsen L., den Outer P., Putz E., Rembges D., di Sarra A., Siani A., Silbernagl R., Siljamo N., Slaper H., Smolskaia I., Steinmetz M., Taalas P., Tourpali K., Vanicek K., Webb A., van Weele M., Weihs P.: The European Database for Ultraviolet Climatology and Evaluation (EDUCE). In: Proceedings of the 6th European Symposium on Stratospheric Ozone, 2-6 September 2002, Göteborg, Sweden, 404-407, 2002.

Popular Articles

The articles are in Estonian if not indicated otherwise.

Astronomy

Annuk K.: Wolf-Rayet tüüpi tähtedest ja nende spektraalmuutlikkusest. Tähetorni Kalender 2004, 69-83, 2003.

Einasto J.: Konverentsid Rios ja Cargeses ning kosmoloogia viimased arengud. Tähetorni Kalender 2004, 55-68, 2003.

Einasto J., Leedjärv L.: Võimu ja vaimu tüli. Postimees, 29.01.2003.

Jaaniste H.: Astronoomiahuviliste kaheksas kokkutulek. Tähetorni Kalender 2004, 119-125, 2003.

Jaaniste J.: Veenus üle Päikese. Tähetorni Kalender 2004, 84-90, 2003.

Jõeveer M.: Marsi maastikud. Päikesesüsteemi suurimad vulkaanid. Horisont 1, 32-37, 2003.

Jõeveer M.: Päikese aktiivsuse ootamatu puhang. Tähetorni Kalender 2004, 91-93, 2003.

Jõeveer M.: Hiina kosmoseprogrammist. Tähetorni Kalender 2004, 94-97, 2003.

Jõeveer M.: Mount Stromlo observatooriumi suurtulekahjust ja tulevikuplaanidest. Tähetorni Kalender 2004, 98-101, 2003.

Jõeveer M.: Marsi maastikud. Polaarmütsid. Horisont 2, 38-41, 2003.

Jõeveer M.: Augustis Marsi suur vastasseis! Ei mingit katastroofi! Horisont 4, 28-32, 2003.

Leedjärv L.: Euroopa astronoomid said kokku Budapestis. Tähetorni Kalender 2004, 49-54, 2003.

Leedjärv L.: Kõrgelt näeb kaugemale. Lehed ja Tähed. Looduse ja Teaduse Aastaraamat 2003, MTÜ Loodusajakiri, 62-70, 2003.

Leedjärv L.: Astronomers Unravel the Secrets of the Universe. Estonia (2nd Edition), Ministry of Foreign Affairs, 53-54, 2003.

Pustylnik I.: Kosmilised purskallikad. Horisont 5, 30-35, 2003.

Pustylnik I.: Akadeemik Arved Sapari juubel. Tähetorni Kalender 2004, 109-114, 2003.

Tago E.: Universumi reliktkiirgus on kaardistatud. Vaatleja, jaanuar-veebruar 2003.

Tago E.: Hubble'i teleskoop jätkab uue kaameraga edukalt. Vaatleja, mai-juuni 2003.

Tago E.: Infrapunane kosmoseteleskoop NASA-lt MRP aastapäevaks! Vaatleja, juuli-august 2003.

Tago E.: Must auk heliseb kuulmatult madalalt. Vaatleja, september-oktoober 2003.

Tago E.: Kas musta augu teke Linnutees laastas elu Maal? Vaatleja, september-oktoober 2003.

Tuvikene T.: Hugo Raudsaar 80, Tõutsimäe külatähetorn 40. Tähetorni Kalender 2004, 115-118, 2003.

Viik T.: Astronoomia suurkogu teisel pool Maakera. Tähetorni Kalender 2004, 43-48, 2003.

Geophysics

Eerme K.: Kas elaksime üle tuumaöö ja tuumatalve? Eesti Loodus 4, 36-39, 2003.

Eerme K.: Elame kliimaheitluste vaherahu ajas. Horisont 3, 35-39, 2003.

Eerme K.: Muutumatu kliima tähendaks ajaloo lõppu. Akadeemia 10, 2051-2085, 2003.

Jaagus J., Kallis A.: On siis Eesti kliima muutumas? Lehed ja Tähed. Looduse ja Teaduse Aastaraamat 2003, 53-61, 2003.

Kallis A.: Jõulud olid sinimustvalged. Maaleht, 03.01.2003.
Kallis A.: Kes tegi mullu Eestis ilma? Maaleht, 09.01.2003.
Kallis A.: Ridi-radi-ralla, pakane on valla! Postimees, 11.01.2003.
Kallis A.: Kolm päikest pakase vastu. SL Õhtuleht, 11.01.2003.
Kallis A.: Jõnksuline näärikuu. Maaleht, 06.02.2003.
Kallis A.: Ilmaparandajate partei suur võimalus. Postimees, 11.02.2003.
Kallis A.: USA talv jätkub. Maaleht, 20.02.2003.
Kallis A.: Kevad ei jää tulemata. Linnaleht, 21.02.2003.
Kallis A.: Soojarekord jäi tulemata. Eesti Loodus 2/3, 76, 2003.
Kallis A.: Iraagis läheb palavaks. SL Õhtuleht, 01.03.2003.
Kallis A.: Kitseaasta alguskuu. Maaleht, 06.03.2003.
Kallis A.: Tõeline küünla-, suusa- ja võistluskuu. Postimees, 11.03.2003.
Kallis A.: Iditarodi võidusõit. Maaleht, 20.03.2003.
Kallis A.: Uued tuuled tähtede maailmas. SL Õhtuleht, 01.04.2003.
Kallis A.: Mõnus märts. Maaleht, 03.04.2003.
Kallis A.: Jäävabaks Eesti meri! Jäävabaks Eesti pind! Postimees, 08.04.2003.
Kallis A.: Külma talve järel tuleb harva varajane kevad. 12 kuud, märts, 2003.
Kallis A.: Kunas algab kevad? Maaleht, 17.04.2003.
Kallis A.: Oled see sina või sinu kloon? SL Õhtuleht, 30.04.2003.
Kallis A.: Tallinnas sõnnikuta hooleta. Maaleht, 08.05.2003.
Kallis A.: Kas me sellist aprilli siis tahtsimegi? Postimees, 13.05.2003.
Kallis A.: Juuni algab ehk ilusti. Maaleht, 20.05.2003.
Kallis A.: Naised teevad ilma. Maaleht, 22.05.2003.
Kallis A.: Kuhu jääb soojataat? Maaleht, 05.06.2003.
Kallis A.: Maikuu kui morninäoline modell. Postimees, 10.06.2003.
Kallis A.: Teeme ise jaani ilma! Maaleht, 19.06.2003.
Kallis A.: Jaanipäevaseid projekte. SL Õhtuleht, 20.06.2003.
Kallis A.: Kui soe suvi tuleb, kui suvi üldse tuleb. Nelli Teataja, 20.06.2003.
Kallis A.: Riia linn on meie! Maaleht, 03.07.2003.
Kallis A.: Jaan lasi päikesel piduliste peale paista. Postimees, 08.07.2003.
Kallis A.: Vanasõnad teevad ilma. Maaleht, 17.07.2003.
Kallis A.: Verejanulistele ilmahuvilistele. SL Õhtuleht, 23.07 2003.
Kallis A.: Maa pööritab naba. SL Õhtuleht, 02.08.2003.
Kallis A.: Juuli näitas kuuma palet. Maaleht, 07.08.2003.
Kallis A.: Juuli astus sammukese Euroopa suunas. Postimees, 12.08.2003.
Kallis A.: Parem soojas surra, kui külmas elada. Maaleht, 21.08.2003.
Kallis A.: Kliimalt suur riik. Eesti Päevaleht. 23.08.2003.
Kallis A.: Parem külmas elada ... Maaleht, 04.09.2003.
Kallis A.: Lõikuskuu kontrastid. Postimees, 09.09.2003.
Kallis A.: Eesti kohal haigutav osooniauk on ohutu. Sakala, 18.09.2003.
Kallis A.: Paras Päike. Maaleht, 18.09.2003.
Kallis A.: Isabel ajas Bushi Valgest Majast välja! SL Õhtuleht, 20.09.2003.
Kallis A.: Isabel tuleb veel tagasi! Maaleht, 02.10.2003.
Kallis A.: Sügis tõi öökülmad ja lindude rände. Postimees, 07.10.2003.
Kallis A.: Uputab, ei uputa?! Horisont 5, 12-17, 2003.
Kallis A.: Sügis tuli vee ja vilega. Maaleht, 09.10.2003.
Kallis A.: Kokkuhoidlik kellapoliitika. SL Õhtuleht, 25.10.2003.
Kallis A.: Viinakuu tali tuli ainult korraks. Maaleht, 06.11.2003.
Kallis A.: Viinakuu lõppes tormiga päikesel ja maal. Postimees, 11.11.2003.
Kallis A.: Päike möllab. Maaleht, 13.11.2003.
Kallis A.: Me tusameele talvekuu. Maaleht, 04.12.2003.
Kallis A.: November Eestis: soe, rõske, märg ja pime. Postimees, 09.12.2003.
Kallis A.: Kuidas Mõõta külmatunnet. Maaleht, 11.12.2003.
Kallis A.: Tundeline teekond Tallinnast Tartu. SL Õhtuleht, 29.12.2003.
Kallis A.: Ilm näitas taas kurja ja kavalat nägu Postimees, 31.12.2003.
Kallis A.: Kui külm on külm ehk kas 2002/2003 talv oli erakordne? Aastaraamat Kes?Mis?Kus? 2004. Tänapäev, 16, 2003.
Kallis A.: Ilm. Aastaraamat Kes?Mis?Kus? 2004, Tänapäev, 411-424, 2003.
Kallis A.: Ilmus Eesti kiirguskliima teatmik. Keskkonnatehnika 6, 27, 2003.
Peterson U.: Kümne aasta raiesmikud satelliidipiltidel. Eesti Loodus 4, 154-156, 2003.
Peterson U.: Kõrgemalt näeb metsa paremini. Eesti Mets 4, 10-14, 2003.
Peterson U.: Seni on riigimetsa rohkem raiutud. Metsaleht, 23.12.2003.
Sulev M.: Energiavõsast ja selle uurimisest Tõraveres. Tähetorni Kalender 2004, 102-108, 2003.
Veismann U.: Kaks raamatut elu otsingutest kosmosest. Akadeemia 1, 170-174, 2003.

Grant Reports

Gramann M.: Large-Scale Structure and Motions in the Universe. Grant of the Estonian Science Foundation No. 3601, Final Report. Tartu Observatory, 20 pp., 2003.

Veismann U.: Solar UV Radiation in Estonia. Grant of the Estonian Science Foundation No. 3609, Final Report. Tartu Observatory, 42 pp., 2003.

Preprints

Gramann M., Suhhonenko I.: Peculiar Velocities of Galaxy Clusters: a Comparison with the Linear Theory. [astro-ph/0307092].

Hütsi G., Einasto J., Saar E., Tucker D.L., Einasto M.: Luminosity Function of the Sloan and Las Campanas Redshift Surveys. [astro-ph/0212327].

Kubát I., Krticka J., Pustylnik I.: Radiation Induced Coronal Wind in Late B Stars. New Astronomy 9/3, 215-224, 2004.

Meetings

Astronomy

The Meeting of the Expert Panel in Astronomy and Space Sciences (Helsinki, Finland, 27.01.2003) - M. Gramann.

Board of Directors Meeting, "Astronomy and Astrophysics" (Heraklion, Greece, 10.05.2003) - L. Leedjärv.

Council Board Meeting of Euro-Asian Astronomical Society (Moscow, Russia, 14.05.-18.05.2003) - I. Pustylnik.

GAIA Working Group on Relativistic Model and Quasi-Inertial Reference Frame (Dresden, Germany, 12.06.-13.06.2003) - V. Malyuto.

Conference "When Cosmology and Fundamental Physics Meet" (Marseille, France, 23.06.-26.06.2003) - I. Suhhonenko.

CREST Initiative on the Opening of National RTD Programmes - Astrophysics (Amsterdam, The Netherlands, 24.06.2003) - T. Viik.

XXV General Assembly of the International Astronomical Union (Sydney, Australia, 13.07.-26.07.2003) - T. Viik.

X Marcel Grossmann Congress (Rio de Janeiro, Brazil, 21.07.-26.07.2003) - J. Einasto.

Einasto J.: Spatial Distribution of SDSS Clusters and Superclusters (invited report).

Joint European and National Astronomy Meeting JENAM 2003 (Budapest, Hungary, 25.08.-30.08.2003) - L. Leedjärv, I. Pustylnik.

Leedjärv L.: High-Velocity Jets from Symbiotic Stars and Other Astrophysical Systems (invited review on the Minisymposium No 4 "Active Stars and Interacting Binaries").

Pustylnik I.: Modelling the Irradiated Atmospheres of Unevolved Companions in Pre-Cataclysmic Binaries (PCB) (oral presentation on the same Minisymposium).

Summer School for Cosmology (Cargese, France, 09.09.-20.09.2003) -
J. Einasto.

Einasto J.: Dark Matter: Early Considerations (lecture course).

Põhjamaade Planetaariumiassotsiatsiooni konverents (Tartu, Estonia, 12.09.-14.09.2003) - E. Tago.

Conference "Stellar Photometry: Past, Present and Future" (Vilnius, Lithuania, 17.09.-20.09.2003) - I. Pustylnik, T. Tuvikene.

Kalv P., Harvig V., Aas T., Pustylnik I.: Dual-Star Photometer in Tallinn Observatory (poster).

Tuvikene T., Kolka I.: Experience in CCD Photometry at Tartu Observatory (poster).

Pustylnik I.: UBV Photometry of Selected Long-Period Eclipsing Binaries in Tallinn Observatory (oral presentation).

GAIA Photometry Working Group Workshop (Leiden, The Netherlands, 09.10.-10.10.2003) - I. Kolka, V. Malyuto.

Kolka I.: Emission Line Stars and the MBP System of GAIA (oral presentation).

Malyuto V.: Comparison of Minimum Distance and Perturbation Methods in Classification for GAIA (oral presentation).

NATO Advanced Study Institute on Photopolarimetry in Remote Sensing (Yalta, Ukraine, 20.09.-03.10.2003) - T. Viik.

Viik T.: Numerical Test of an Inverse Problem Algorithm for Polarized Radiative Transfer (oral presentation).

Astronomical Seminar (St. Petersburg State University, St. Petersburg, Russia, 16.10.2003) - A. Sapar, T. Viik.

Sapar A.: A New FORTRAN Code SMART for Physics of Stellar Atmospheres (oral presentation).

Viik T.: Numerical Test of an Inverse Problem Algorithm for Polarized Radiative Transfer (oral presentation).

Astronomical Seminar (Nicolaus Copernicus Astronomical Centre, Torun branch, Torun, Poland, 23.10.2003) - A. Hirv, , A. Puss.

Hirv A.: A Spectroscopic Study of Wolf-Rayet Binary V444 Cyg (oral presentation).

Leedjärv L.: Spectroscopy and Photometry of the Symbiotic Star AG Draconis 1997-2003 (oral presentation).

IAU Colloquium No 194 "Compact Binaries in the Galaxy and Beyond" (La Paz, Mexico, 17.11.-21.11.2003) - L. Leedjärv.

Leedjärv L., Tomov T., Miko\lajewski M., Burmeister M.: CH Cygni and Other Symbiotic Stars with Low Luminosity Hot Components (poster).

A School on the Physics of Galaxy Formation (Allahabad, India, 16.12.-29.12.2003) - A. Tamm.

A Winter School "The Origin of Galaxies" (Jerusalem, Israel, 30.12.2003-08.01.2004) - A. Tamm, I. Suhhonenko.

Geophysics

Juubelikonverents "80 aastat hüdromeetrilisi vaatlusi Tiirikoja Järvejaamas" (Mustvee, Estonia, 04.02.2003) - V. Russak, A. Kallis.

Kallis A., Russak V.: Päikesekiirgus Tiirikojal ja Tõraveres, sarnasused ja erinevused (oral presentation).

Swedish Meteorological and Hydrological Institute Seminar (, Sweden, 05.03.2003) - O. Kärner.

Kärner O.: Experience of Using CM-SAF Cloud Algorithm for Cloud Classification in the Arctic Conditions (oral presentation).

VALERI Program Meeting and Seminar in INRA (Avignon, France, 20.03.-21.03.2003) - T. Nilson.

Nilson T.: Inversion of Gap Fraction Data for Forest Stands (oral presentation).

Nordic Ozone Group (NOG) Meeting (Tartu, Estonia, 21.03.-22.03.2003)- K. Eerme, U. Veismann, R. Koppel, S. Lätt.

Eerme K.: Backward Estimation of Erythemal Doses in Estonia (oral presentation).

Veismann U., Eerme K., Koppel R., Maasik E.-M.: UV Sensors Based on the Solar Blind Phototubes (poster).

4th EDUCE Meeting (Saariselkä, Finland, 26.03.-28.03.2003) - K. Eerme.

Eerme K.: UV Climatology and Calculation of Weighted Doses (oral presentation).

Kliimakonverents ,,Inimene ja keskkond" (Kuressaare, Estonia, 21.04.2003) - V. Russak.

Russak V.: Muutused Eesti kiirguskliimas viimase poolesajandi jooksul (oral presentation).

Basic Surface Radiation Network Workshop (Zürich, Switzerland, 25.04.-26.04.2003) - A. Kallis.

Kallis A.: The New Actinometrical Instruments at Tartu-Tõravere Station (oral presentation).

World Meteorological Organization XIV Congress (Geneva, Switzerland, 05.05.-24.05.2003) - A. Kallis.

Kallis A., Russak V., Ohvril H.: Estonian Solar Radiation Monitoring (poster).

Joint Remote Sensing Seminar of Helsinki University and Tartu Observatory, (Helsinki, Finland, 08.05.-09.05.2003) - T. Nilson, A. Kuusk, M. Lang, T. Lükk, M. Mõttus, H. Böttcher.

Kuusk A.: Reflectance Spectra of Ground Vegetation in Sub-boreal Forests (oral presentation).

Mõttus M.: Measurement and Modelling of the Vertical Distribution of Sunflecks, Penumbra and Umbra in Willow Coppice (oral presentation).

Böttcher H.: Retrieval of Forest Leaf Area Index (LAI) from SPOT Images in Järvselja by Means of Reflectance Model Inversion (oral presentation).

Conference on Research for Rural Development 2003 (Jelgava, Latvia, 21.05.-24.05.2003) - U. Peterson.

Peterson U.: Forest Mapping of Eastern Baltic Region with Landsat Thematic Mapper Winter Images (oral presentation).

Eesti kaugseire seminar (Tartu Observatoorium, Tõravere, Estonia, 03.06.2003) - U. Peterson, M. Lang, T. Lükk, K. Eerme, V. Russak, T. Nilson, A. Kuusk, H. Böttcher.

Eerme K.: Atmosfääri muutlikkust Eesti kohal iseloomustava andmebaasi koostamine (poster).

Peterson U.: Olulisemad maakasutuse ja maakatte muutused Eestis satelliidipiltide 10-aastasest aegreast mõõdetuna (oral presentation).

Lang M.: Lageraiete kaardistamine Landsat TM piltidelt (oral presentation).

Lükk T.: KNN-meetodi rakendamine metsade takseerparameetrite hindamisel ja kaardistamisel (oral presentation).

Ohvril H., Teral H., Okulov O., Russak V., Reinart A.: Atmosfääri aerosoolse spektraalse optilise paksuse arvutamine päikese integraalsest otsekiirgusest (poster).

Nilson T.: Rootsi kaugseireprogrammist RESE. Kaugseire rakendusvõimalusi erinevates valdkondades (oral presentation).

ISES Solar World Congress, (Göteborg, Sweden, 14.06.-19.06.2003) - V. Russak, A. Kallis.

Mellikov E., Tomson T., Kallis A., Russak V.: Steady-State Variability of Solar Irradiance (oral presentation).

Final EDUCE Meeting (Krakow, Poland, 01.10.-03.10.2003) - K. Eerme.

Eerme K.: UV Climatology of the TO site and WP1, WP3 tasks (oral presentation).

Workshop "Ozone and UV Radiation over Central Europe" (Jachranka, Poland, 20.10.-22.10.2003) - K. Eerme, U. Veismann.

Eerme K.: Changes in Spring-Summer Cirrus Cloud Amount and Other Cloudiness Related Characteristics over Estonia (1958-2002) (oral presentation).

Veismann U.: UV Sensors Based on the Solar Blind Phototubes (oral presentation).

Workshop of Atmospheric Physics (Zürich, Switzerland, 20.11.2003) - V. Russak.

Russak V.: Changes in Radiation Climate in Estonia (1955-2002) (oral presentation).

Workshop of Radiation Climate (Davos, Switzerland, 21.11.2003) - V. Russak.

Russak V.: Changes in Radiation Climate in Estonia (1955-2002) (oral presentation).

Miscellaneous

Olev Avaste 70. sünniaastapäevale pühendatud mälestuste pärastlõuna (Tartu, Estonia, 21.02.2003) - T. Viik, O. Kärner, U. Veismann, V. Russak, K. Eerme, R. Koppel.

Viik T.: Šifrinist Vainikko kaudu IRSni (oral presentation).

Veismann U.: OA Faza projektis ja purjetamises (oral presentation).

Eerme K.: OA ja ööpilved semmimas ChVga (oral presentation).

Kärner O.: OA ja satelliidiandmed Eestis (oral presentation).

The 5th EUMETSAT Central and Eastern European User Forum (Zagreb, Croatia, 02.04.-04.04.2003) - T. Viik.

Charles Villmanni 80. sünniaastapäevale pühendatud seminar (Tõravere, Estonia, 11.04.2003) - most of the staff of the Observatory.

Viik T.: Ch Villmanni eluloolisi tähiseid (oral presentation).

Veismann U.: Ch. Villmann ja kosmoseprojektid (oral presentation).

Eerme K.: Ch. Villmann - helkivate ööpilvede uurimise suurkuju (oral presentation).

The VIth Biennial Meeting of History of Astronomy, (University of Notre Dame, Indiana, USA 19.06.-22.06.2003) - I. Pustylnik.

Pustylnik I.: Ernst Julius Öpik (1893-1985) - Scientific Biography (oral presentation).

3rd EUROSKIN Conference: Identification and Management of Risk Factors in Skin Cancer, (Stockholm, Sweden, 16.09.-19.09.2003) - K. Eerme was a co-author of the poster.

Seckmeyer G., Kjeldstad B., Putz E., Taalas P., Gardiner B., Bais A., Slaper H., Kylling A., Webb A., Engelsen O., Blumthaler M., Lenoble J., Janoush M., Krzyscin J., Eerme K., Litynska Z., Gillotay D., di Sarre A. G., Feister U., Steinmetz M., Gröbner J., Siani A. M., Henriques D., van Weele M., Brogniez C., Koskela T.: EDUCE - European Database for Ultraviolet Climatology and Evaluation (poster).

EUROSCIENCE Conference "European Research Area, Regional Scientific Cooperation in Southeast Europe, Pathways for Stabilizing the RTD Potential" (Bucharest, Romania, 25.09.-29.09.2003) - I. Pustylnik.

Eesti Üliõpilaste Looduskaitseringi 45. aastapäeva vilistlaskonverents (Paide, Estonia, 10.10.2003) - U. Peterson.

Peterson U.: Satelliidipiltide aegridadest mõõdetud lageraielankidest Eestis (oral presentation).

Seminar "Keskkonna kaugseire rakendusi - mis on Eestist näha ülalt?" (Tallinn, Estonia, 17.10.2003) - U. Peterson.

Peterson U.: Eesti metsakaart ja selle edasiarendused maastike muutuste kaugseires (oral presentation).

Editing of the Proceedings of the Tenth Annual Meeting of the Society for European Astronomy in Culture (SEAC), "Cultural Context for the Archaeoastronomical Data and the Echoes of Cosmic Catastrophic Events", Tartu 2002 - I. Pustylnik.

Chairing the National Examinational Board, Estonian Maritime Academy (Tallinn, Estonia, May-June, 2003) - A. Kallis.

Visits to other Institutes and our Guests

Astronomy

J. Pelt - Oulu University, Oulu (Finland); 10.02.-22.02.2003.

T. Nugis - Astronomical Institute of Utrecht University (The Netherlands); 01.04.- 29.04.2003.

M. Gramann - Max-Planck Institut für Astrophysik, Garching (Germany); 21.04.-29.04.2003.

V. Malyuto - Dresden Technical University, Dresden (Germany); 10.06.-30.06.2003.

E. Saar - València University, València (Spain); 13.06.-10.07.2003.

E. Saar - València University, València (Spain); 16.09.-15.12.2003.

A. Sapar, T. Viik - St. Petersburg State University, St. Petersburg (Russia); 13.10.-17.10.2003.

J. Pelt - Oulu University, Oulu (Finland); 21.10.-19.11.2003.

L. Leedjärv, A. Hirv, A. Puss - Centre for Astronomy, Nicolaus Copernicus University, Torun (Poland); 22.10.-29.10.2003.

M. Gramann - Tuorla Observatory, University of Turku (Finland); 10.11.-17.11.2003.

I. Pustylnik - Charles University, Prague (Czech Republic); 16.11.-04.12.2003.

I. Vurm - NORDITA, Copenhagen (Denmark); 24.11.-04.12.2003.

G. Hütsi - Max-Planck Institut für Astrophysik, Garching (Germany) - whole year.

Geophysics

T. Viik - Finnish Meteorological Institute, Helsinki (Finland); 29.01.-30.01.2003.

T. Nilson - Institute National de la Recherche Agronomique (INRA), Avignon (France); 19.03.-23.03.2003.

A. Kallis - Institute for Atmospheric and Climate Science, ETH Zürich (Switzerland); 22.04.-13.05.2003.

M. Mõttus - Helsinki University and Finnish Forest Research Institute, Helsinki (Finland); 08.05.-09.05.2003.

A. Kuusk - Lund University (Sweden); 14.10.-16.10.2003.

V. Russak - Institute for Atmospheric and Climate Science, ETH Zürich and World Radiation Center, Davos (Switzerland); 19.11.-23.11.2003.

Guests of the observatory

Pauline Stenberg - Helsinki University (Finland); 15.01.-17.01.2003.
Miina Rautiainen - Helsinki University (Finland); 15.01.-17.01.2003.
Volker Müller - Institute for Astrophysics, Potsdam (Germany); 10.03.-15.03.2003.
Pekka Heinämäki - Tourla Observatory, University of Turku (Finland); 10.03.-15.03.2003.
Jevgeni Ustinov - Jet Propulsion Laboratory, NASA, Pasadena (USA); 28.04.-02.05.2003.
Stephen N. Floor - University of Kansas, Lawrence, Kansas (USA); 12.06.2003.
Samppo Smolander - Rolf Nevanlinna Institute, Helsinki (Finland); 27.06.2003.
Kim J. Brown - Ohio University, (USA); 27.06.2003.
Teimuraz Shvelidze - Abastumani Observatory (Georgia); 23.07.-26.07.2003.
Henny Lamers - Astronomical Institute of Utrecht University (The Netherlands); 11.08.-31.08.2003.
Pekka Heinämäki - Tuorla Observatory, University of Turku (Finland); 20.09.-30.09.2003.
Atsumu Ohmura - Institute for Atmospheric and Climate Science, Zürich (Switzerland); 17.10.2003.
Krzystof Czart - Centre for Astronomy, Torun University (Poland); 15.11.-30.11.2003.
Pauline Stenberg - Helsinki University (Finland); 18.11.-20.11.2003.
Miina Rautiainen - Helsinki University (Finland); 18.11.-20.11.2003.

Seminars at the Observatory

Astronomy

22.01.2003 - Mihkel Jõeveer: Galaktika perifeeria uudiseid.
29.01.2003 - Tõnu Kipper: Viimase He-sähvatuse tähtede tekkelugu.
05.02.2003 - Jaak Jaaniste, Maret Einasto: Lõikame jõulusaia.
12.02.2003 - Erik Tago: Mõtteid Väga Suure Teleskoobi nime ümber.
19.02.2003 - Andres Kuperjanov: Muistsete eestlaste tähistaevas, II osa.
13.03.2003 - Volker Müller (Potsdam Observatory): Cosmological Simulations: Cluster Mergers, Supercluster Network and Voids.
19.03.2003 - Tõnu Viik: Johann Heinrich Mädleri kalendrireform, mis jäi toimumata.
02.04.2003 - Mihkel Jõeveer: Sissejuhatus püramidoloogiasse.
16.04.2003 - Izold Pustylnik: Carahunge (Armeenia) - maailma vanim observatoorium?
07.05.2003 - Enn Saar: WMAP ja esimesed tähed.
14.05.2003 - Tõnu Viik: Mis on OPTICON?
21.05.2003 - Laurits Leedjärv: Astronomy and Astrophysics direktorite nõukogu koosolekust Kreetal.
28.05.2003 - Izold Pustylnik: Lühiuudiseid Euro-Aasia Rahvusvahelisest Astronoomia Ühingust.
04.06.2003 - Enn Saar: Stephen Hawking maailma algusest.
12.06.2003 - Stephen N. Floor (University of Kansas): Eccentricity Evolution in Simulated Galaxy Clusters.
21.08.2003 - Henny Lamers (Utrecht University): Nova Cyg 1992: an Empirical Model.
10.09.2003 - Laurits Leedjärv ja Izold Pustylnik: Muljeid Budapesti konverentsilt JENAM 2003.
17.09.2003 - Tõnu Viik: Eesti asja ajamine Amsterdamis ja Sydneys.
01.10.2003 - Jaan Einasto: Ülevaade suvistest teaduslähetustest.
08.10.2003 - Izold Pustylnik, Taavi Tuvikene: Ülevaade konverentsist "Stellar Photometry: Past, Present and Future" Vilniuses.
15.10.2003 - Meenutame, et 22. oktoobril möödub 110 aastat sünnist.
22.10.2003 - Jaan Einasto, Maret Einasto: Sloani ja Las Campanase ülevaadete analüüs.
29.10.2003 - Tõnu Viik: Ülevaade Krimmis ja Peterburis toimunud üritustest.
05.11.2003 - Jaan Einasto, Maret Einasto: Sloani ja Las Campanase ülevaadete analüüs. VOL II.
12.11.2003 - Anti Hirv: Wolf-Rayet kaksiksüsteem V444 Cyg.
26.11.2003 - Tõnu Viik: Thomas Clausen - karjapoisist professoriks.
03.12.2003 - Laurits Leedjärv: Kompaktsetest kaksiktähtedest Mehhikos, meie Galaktikas ja kaugemalgi.
10.12.2003 - Izold Pustylnik: Kuidas E.J. Öpik avastas, et Jupiter on rohkem kui planeet.
17.12.2003 - Laur Järv (Jena Ülikool): Kiirenevalt paisuv universum ja stringiteooria kompaktifitseerimine.

Geophysics

17.01.2003 - Mait Lang, Tõnu Lükk, Rainis Uiga ja Johannes Anniste: Raiete kaardistamine satelliidipiltidelt.
24.01.2003 - Kalju Eerme: Cirrus-pilvede hulk Tõraveres suvedel 1957-2002.
28.03.2003 - Tiit Nilson ja Andres Kuusk: Taimkatte analüsaatori andmetöötlusest metsade jaoks.
04.04.2003 - Olavi Kärner: Arktika pilvkatte määramise CM-SAF meetodi uurimisest kahe satelliidi andmete alusel.
02.05.2003 - Andres Kuusk, Mait Lang, Tiit Nilson: Metsa alustaimestiku peegeldumisspektrid.
16.05.2003 - Madis Sulev ja Matti Mõttus: Sellesuvised mõõtmised energiavõsas.
30.05.2003 - Piia Post (Tartu Ülikool): Broomoksiid vabas troposfääris GOME andmete alusel.
12.09.2003 - Matti Mõttus: Ülevaade ScandLaser'il toimunust.
17.10.2003 - Prof. Atsumu Ohmura (ETH Zürich): New Findings in Radiation and Heat Balance of the Earth.
05.12.2003 - Jaak Jaagus (Tartu Ülikool): Atmosfääri tsirkulatsioon Eesti kliima ja ilmastiku kõikumiste kujundajana.

Cosmology

14.01.2003 - Gert Hütsi: SZ efekt ning superparvede-tühikute võrgustik.
11.02.2003 - Erik Tago, Enn Saar: Galaktikaparvede leidmise meetoditest.
25.02.2003 - Ivan Suhhonenko: Ülevaade doktoritööst "Large-Scale Motions in the Universe".
11.03.2003 - J. Einasto, M. Einasto, V. Müller, E. Saar, I. Suhhonenko, E. Tago: Superstruktuuri uurimise perspektiivid.
01.04.2003 - Urmas Haud: Vesinikuülevaadete "puhastamine".
15.04.2003 - Enn Saar: WMAP ja esimesed tähed.
13.05.2003 - Mirt Gramann: Numbrilisi muljeid Saksamaalt.
27.05.2003 - Ingrid Pärn: Halode faasimudelid.
27.05.2003 - Juhan Liivamägi: Parvesõrmed.
07.10.2003 - Pekka Heinämäki (Tuorla Observatoorium): DWRNP (Do We Really Need Planck?)
18.11.2003 - Urmas Haud: Raadioastronoomiliste vaatluste alused. I. Raadiokujutis.
02.12.2003 - Urmas Haud: Raadioastronoomiliste vaatluste alused. II. Spektromeetria.

Membership in scientific organizations

Academia Europaea - J. Einasto
Akademische Gesellschaft für Deutschbaltische Kultur - T. Viik
ALLEA Science and Ethics Committee - E. Ergma
American Astronomical Society - J. Einasto
Board of Directors "Astronomy and Astrophysics" - L. Leedjärv
Board of the Tartu Astronomy Club - E. Tago
Editorial Board "Agricultural and Forest Meteorology" - A. Kuusk
Editorial Board of "Central European Journal of Physics" - I. Pustylnik
Editorial Board "Journal of Quantitative Spectroscopy and Radiative Transfer" - T. Viik
Eesti Astronoomia Selts - K. Annuk, J. Einasto, M. Jõeveer, T. Kipper, I. Kolka, L. Leedjärv, T. Nugis, J. Pelt, A. Puss, I. Pustylnik, M. Ruusalepp, L. Sapar, E. Tago, P. Traat, U. Veismann, T. Viik
Eesti Füüsika Selts - A. Aret, K. Eerme, J. Einasto, T. Kipper, , E. Saar, A. Sapar, M. Sulev, P. Tenjes, T. Viik
Eesti Geograafia Selts - A. Kallis
Eesti Kvaliteediühing - U. Veismann
Eesti Looduskaitse Selts - M. Sulev
Eesti Looduseuurijate Selts - K. Eerme, A. Kallis, R. Koppel, V. Russak, A. Sapar, M. Sulev, U. Veismann, T. Viik
Eesti Teadlaste Liit - J. Einasto, E. Ergma, A. Kallis, T. Viik
Estonian Academy of Sciences - J. Einasto, E. Ergma, A. Sapar
Estonian Council of Scientific Competence - T. Viik (Vice-Chair)
Estonian National Committee on Astronomy - J. Einasto, E. Ergma, , E. Saar, T. Viik (Chair)
Estonian Geophysical Committee - K. Eerme
European Astronomical Society - K. Annuk, J. Einasto, E. Ergma, V. Harvig, M. Jõeveer, T. Kipper, I. Kolka, L. Leedjärv, V. Malyuto, T. Nugis, I. Pustylnik, V.-V. Pustynski, E. Saar, A. Sapar, L. Sapar, E. Tago, P. Tenjes, U. Veismann, J. Vennik, T. Viik
EUROSCIENCE - I. Pustylnik
Euro-Asian Astronomical Society - A. Aret, J. Einasto, M. Jõeveer, V. Malyuto, I. Pustylnik, A. Sapar
GAIA Classification Working Group - V. Malyuto
GAIA Photometry Working Group - I. Kolka
German Astronomical Society - J. Einasto
Field Editor "Agronomie. Agriculture and Environment" - A. Kuusk
Finance Sub-Committee of the IAU - T. Viik
International Astronomical Union - K. Annuk, J. Einasto, M. Einasto, E. Ergma, M. Gramann, U. Haud, M. Jõeveer, T. Kipper, I. Kolka, L. Leedjärv, V. Malyuto, T. Nugis, J. Pelt, I. Pustylnik, E. Saar, A. Sapar, L. Sapar, E. Tago, P. Tenjes, P. Traat, U. Veismann, J. Vennik, T. Viik
Royal Astronomical Society - J. Einasto (associated member), E. Ergma (also member of a temporal standing committee)
Society for European Astronomy in Culture - I. Pustylnik
Ultraviolettkiirguse, osooni ja aerosoolide uurimise koordineerimise Eesti Nõukogu - K. Eerme, U. Veismann.

Teaching

Lecture courses

Astronomy

History of Astronomy / Astronoomia ajalugu - M. Jõeveer, Tartu University.

Swift Stellar Evolutionary Code - a Useful Educational Tool - I. Pustylnik, Charles University, Prague, Czech Republic.

Astronomical Time Series Analysis /Astronoomiliste aegridade analüüs - J. Pelt, Oulu University.

Astronomy / Astronoomia - P. Tenjes, Tartu University.

General Astronomy / Üldastronoomia - P. Tenjes, Tartu University.

Master Seminar in Astrophysics / Astronoomia magistriseminar - P. Tenjes, Tartu University.

Atomic and Nuclear Physics / Aatomi- ja tuumafüüsika - P. Tenjes, Tartu University.

Mathematical Physics I / Matemaatiline füüsika I - P. Tenjes, Tartu University.

Introduction to Thermodynamics and Statistical Physics / Sissejuhatus termodünaamikasse ja statistilisse füüsikasse - P. Tenjes, Tartu University.

Astronomy/Astronoomia - A. Puss, Nõo High School.

Geophysics

Environmental Sciences / Keskkonnateadused - K. Eerme, Tartu University.

Environmental Science / Keskkonnaõpetus - K. Eerme, Tartu University.

Introduction to Geophysics / Sissejuhatus geofüüsikasse - K. Eerme, Tartu University.

Computer-Aided Measurements / Arvutijuhitavad mõõtmised - U. Veismann together with A. Mirme, Tartu University.

Remote Sensing in Forestry / Metsade kaugseire - T. Nilson ja M. Lang, Estonian Agricultural University.

Remote Sensing of Nature / Looduse kaugseire - T. Nilson ja M. Lang, Estonian Agricultural University.

Vegetation Remote Sensing / Taimkatte kaugseire - T. Nilson, Tartu University.

Fundamentals of Remote Sensing / Kaugseire alused - U. Peterson, Tartu University.

Geographic Information Systems / Geograafilised informatsioonisüsteemid - U. Peterson, Estonian Agricultural University.

Natural Energy Resources / Loodusressursid - V. Ross, Tartu University.

Physical geography / Füüsiline geograafia - A. Kallis, Estonian Maritime Academy.

Popular lectures

10 intervjuud BNSile, raadiole ja televisioonile - T. Viik.

Tähistaeva uudiseid (Eesti Televisioon, "Pühapäevitaja", 12.01.2003) - L. Leedjärv.

Johann Heinrich Mädleri kalendrireformist (Tartu Tähetorni Astronoomiaring, Tartu, 04.02.2003) - T. Viik.

Päikesesüsteemi tekkimisest (Studium generale Eesti Rahvusraamatukogus, Tallinn, 15.04.2003) - P. Tenjes.

Kerasparvede süsteemid galaktikates (Tartu Tähetorni Astronoomiaring, Tartu, 29.04.2003) - P. Tenjes.

Ettekanne kosmoloogiast ("Vanemuise" Selts, Tartu, 13.05.2003) - J. Einasto.

Kosmoloogia viimased arengud (Taagepera suveülikool, Taagepera, 27.06.2003) - J. Einasto.

Astronoomilistest uuringutest Tartus (Kaitseväe Ühendatud Õppeasutuste suvepäevad, Otepää, 02.08.2003) - J. Vennik.

Planeet Marss (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 09.08.2003) - M. Jõeveer.

Marsi vallutamine (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 09.08.2003) - T. Tuvikene.

Mars Express Online (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 09.08.2003) - P. Tenjes.

Mida Marsil nähtud on (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 09.08.2003) - J. Jaaniste.

V838 Monocerotis (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 10.08.2003) - T. Kipper (presented by K. Annuk).

Wolf-Rayet tähed (Astronoomiahuviliste Üle-Eestiline kokkutulek, Tõravere, 10.08.2003) - K. Annuk.

Keemiliselt pekuliaarsed tähed (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 10.08.2003) - A. Aret.

WMAP ja kosmoloogilised sensatsioonid (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 11.08.2003) - E. Saar.

Muljeid IAU XXV Peaassambleelt Sydney's (Astronoomiahuviliste Üle-Eestiline VIII kokkutulek, Tõravere, 11.08.2003) - T. Viik.

Uudiseid Marcel Grossmani konverentsilt (Astronoomiahuviliste Üle - Eestiline VIII kokkutulek, Tõravere, 11.08.2003) - J. Einasto.

Tartu Observatoorium ja tänapäeva astronoomia (TÜ Füüsikaosakonna üliõpilastele, Tartu, 04.09.2003) - L. Leedjärv.

Universumi struktuur ja selle areng (Von Krahli Akadeemia, Tallinn, 12.09.2003) - P. Tenjes.

Tähed pimedas Universumis (Von Krahli Akadeemia, Tallinn, 12.09.2003) - L. Leedjärv.

Eesti mets ja lageraiealad satelliidipiltide viieteistkümneaastasest aegreast mõõdetuna (Õpetatud Eesti Seltsi koosolek, Tartu, 24.09.2003) - U. Peterson.

SMART-1 Kuule (Eesti Televisioon, "Terevisioon", 01.10.2003) - .

Kosmoloogia viimased arengud (Eesti Looduseuurijate Seltsi 150. juubelikonverents, Tartu, 09.10.2003) - J. Einasto.

Kosmoloogia viimased arengud (Horisondi lugejate infopäev, Tõravere, 11.10.2003) - J. Einasto.

Kosmoloogia viimased arengud (Mereuurijate konverents, Hageri, 12.10.2003) - J. Einasto.

Eesti mets ja lageraiealad satelliidipiltide viieteistkümneaastasest aegreast mõõdetuna (Õpetatud Eesti Seltsi koosolek, Tallinn, 16.10.2003) - U. Peterson.

Fraktalitest Universumis (Eesti Televisioon, "Osoon", 29.10.2003) - .

Universumi struktuur (Eesti Kunstiakadeemia, Tallinn, 03.11.2003) - P. Tenjes.

Thomas Clausen - karjapoisist professoriks (Tartu Tähetorni Astronoomiaring, Tartu, 02.12.2003) - T. Viik.

Universumi reionisatsioon ja tume aine. I. (Teoreetilise füüsika seminar, Tartu, 09.12.2003) - P. Tenjes.

Tähed pimedas Universumis (Vikerraadio "Raadio Ööülikool", 13.12.2003) - L. Leedjärv.

Universumi reionisatsioon ja tume aine. II. (Teoreetilise füüsika seminar, Tartu, 16.12.2003) - P. Tenjes.

Supervising of graduation theses

A. Kuusk - T. Jakobsoo: Erinevate satelliidipildi atmosfäärikorrektsiooni algoritmide võrdlemine (B.Sc.), Tartu University.

U. Peterson - K. Koemets: Satelliidipiltidest koostatud Jõgevamaa metsakaart ja piltidelt mõõdetud lageraiealad (B.Sc.), Estonian Agricultural University.

U. Peterson - K. Kollom: Satelliidipiltidest koostatud Põlvamaa metsakaart ja piltidelt mõõdetud lageraiealad (B.Sc.), Estonian Agricultural University.

E. Saar - L.J. Liivamägi: Parvesõrmed (B.Sc.), Tartu University.

E. Saar - I. Pärn: Halode faasimudelid (B.Sc.), Tartu University.

P. Tenjes - E. Tempel: Regulaarsete galaktikate hüdrodünaamilised mudelid (B.Sc.), Tartu University.

U. Veismann - S. Lätt: Päikese ultraviolettkiirguse spektromeetria (B.Sc.), Tartu University.

Supervising of M.Sc. and Ph.D. theses

K. Annuk - A. Hirv: Spectroscopic and Photometric Investigation of Short-Period Wolf-Rayet Binaries (M.Sc.), Tartu University.

M. Gramann - I. Suhhonenko: Large-Scale Motions in the Universe (Ph.D.), Tartu University.

I. Kolka - T. Eenmäe: Investigation of the Long-Term Spectral Variability of X Persei (M.Sc.), Tartu University.

I. Kolka - T. Tuvikene: Package of Programs for Photometric Data Analysis at Tartu Observatory (M.Sc.), Tartu University.

L. Leedjärv - M. Burmeister: Comparative Study of Two Symbiotic Stars, AG Draconis and EG Andromedae (M.Sc.), Tartu University.

T. Nilson and M. Lang - R. Uiga: Detection of Forest Cuttings from Satellite Images and Finding a Relationship Between Thinning Grade and Reflectance Change (M.Sc.), Estonian Agricultural University.

T. Nilson - H. Böttcher: Remote Sensing of Understorey Leaf Area Index (LAI) (M.Sc.), Georg-August Universitet Göttingen.

V. Russak, A. Kallis - I. Niklus: The Dependence of the Short Wave Radiation Budget Components on the Optical Characteristics of Atmosphere (M.Sc.), Tartu University.

T. Viik - I. Vurm: Radiation Field in a Two-Dimensional Atmosphere (M.Sc.), Tartu University.

Refereeing of theses

K. Eerme - S. Lätt: Päikese ultraviolettkiirguse spektromeetria (B.Sc.), Tartu University.

M. Jõeveer - E. Tempel: Regulaarsete galaktikate hüdrodünaamilised mudelid (B.Sc.), Tartu University.

T. Kipper, J. Pelt - M. Burmeister: Comparative Study of Two Symbiotic Stars, AG Draconis and EG Andromedae (M.Sc.), Tartu University.

T. Kipper, P. Tenjes - T. Tuvikene: Package of Programs for Photometric Data Analysis at Tartu Observatory (M.Sc.), Tartu University.

I. Kolka - A. Hirv: Spectroscopic and Photometric Investigation of Short-Period Wolf-Rayet Binaries (M.Sc.), Tartu University.

L. Leedjärv, A. Puss - T. Eenmäe: Investigation of the Long-Term Spectral Variability of X Persei (M.Sc.), Tartu University.

T. Nilson - I. Vurm: Radiation Field in a Two-Dimensional Atmosphere (M.Sc.), Tartu University.

U. Peterson - R. Uiga: Detection of Forest Cuttings from Satellite Images and Finding a Relationship Between Thinning Grade and Reflectance Change (M.Sc.), Estonian Agricultural University.

E. Saar - I. Suhhonenko: Large-Scale Motions in the Universe (Ph.D.), Tartu University.

E. Tago - L.J. Liivamägi: Parvesõrmed (B. Sc.), Tartu University.

P. Tenjes - I. Pärn: Halode faasimudelid (B.Sc.), Tartu University.

U. Veismann - T. Leemet: Andmehõivesüsteem mitmekanalilise Foucault' kardiograafia uuringuteks (B.Sc.), Tartu University.

U. Veismann - N. Šubina: Solaariumiteenuse tervisekaitsealased aspektid (M.Sc.), Tartu University.