LIST OF ABSTRACTS
Apostolovska G. (a, b) - Arlot J.-E. (a, b ) - Aleksandrov Yu. V. - Bange J.-F. - Barbieri C. - Barucci A. - Bec-Borsenberger A. - Belskaya I. - Benz W. - Binzel R.(a, b) - Birlan M. - Biryukov V. - Blanco C. - Borisov G. - Bowell E.L.G. - Bratsolis E. - Breiter S. - Bretagnon P. - Bykov O. (a, b, c, d) - Casas R.(a, b) - Calvani M. - Chernykh N. S. - Christou A. - Di Martino M. - Elst E.W. - Durech J. - Doressoundiram A. - Fienga A. .(a, b) - Fodera G. - Gnedin Yu. N. - Golubeva] L. - Grynko Y. - Gudkova L. - Hahn G. - Hoffmann M. - Ismailov I.S. - Ivanova V. - Kaasalainen M. - Kocer M. - Komarova N. O. - Krasinsky G.A. - Kryszczynska A. - Kwiatkowski T. - Lupishko, D.F.(a, b) - Lupishko, T.A. - Lopez Garcia, A. - L´vov V. N. - Manek J. - Maslennikov K. L. - McFarland, J. - Michalowski T. - Michel P. - Monet A. K. B. - Monet D. G. - Mottola G. - Perov N. I. - Peixinho N. - Pignata L. - Pitjeva E. V. - Portyankina G. - Rapaport M. (a, b) - Richardson D. - Rosaev A. E. - Rumyantsev V.(a, b, c) - Salvadori L. - Shestopalov D. (a, b) - Shevchenko V.G (a, b, c) - Shkuratov Yu. - Simonia I. - Sigelle M. - Simonia T. - Sumzina N. K. - Tanga P. - Thuillot W. (a, b) - Ticha J. - Tichy M. - Tungalag, N. - Vasyliev M.V. - Velichko F. - Vienne A. - Yagudina E. I.(a, b ) - Zheleznov N.
CCD lightcurves of several asteroids during their last apparitions (Poster)
by APOSTOLOVSKA G.(1) and BORISOV G. (2)
(1)Institute of Physics, Faculty of Natural Sciences, Skopje, R. (Macedonia)
(2)Institute of Astronomy, Bulgarian Academy of Sciences Sofia, (Bulgaria)
CCD photometry of asteroids have been carried out since December 1998 at
Bulgarian National Astronomical Observatory - Rozhen, using 2m RCC telescope
equipped with a CCD camera Photometrics CE200A and since July 2000 using
0.50m/0.70m Schmidt telescope equipped with a CCD camera ST8-E. Possibilities
of further photometric investigations will be discussed.
Observational networks: the mutual events observations (Oral)
by ARLOT J.-E., Institut de mécanique céleste (IMCCE/ Paris obs.)(France)
Since 1973, the mutual events of the natural planetary satellites are
extensively observed because of the high interest of the informations deduced
from their observations. However, these events occur at precise dates and a
network of observers around the world is necessary in order to be able to
observe most of the events. I will remind the past efforts, the results and I
will announce the next occurrence of mutual phenomena of the Galilean
satellites of Jupiter in 2002-2003 which will need again the observational network.
ADAS: Asiago-DLR asteroid survey (Poster)
by BARBIERI C.1, CALVANI M.2, HAHN
G.3, HOFFMANN M.4, MOTTOLA G.3, PIGNATA
L.1, SALVADORI L.1
1 Department of Astronomy, University of Padova (Italy)
2 Astronomical Obervatory of Padova (Italy)
3 DLR, Institute of Space Sensor Technology and Planetary Exploration, Berlin (Germany)
4 Freie Universitat, Intitut fur Geologie, Geophysik und Geoinformatik, Berlin (Germany)
The program to adapt a CCD camera to the S67/92 cm Schmidt telescope at
Cima Ekar is a joint collaboration between the Department of Astronomy and the
Astronomical Observatory of Padova on one side, and DLR Berlin on the other.
The main scientific driver is the discovery and follow up of moving objects
(asteroids, NEO/NEA, TNO, KBO, etc.). However other scientific programs are
possible. DLR has provided the SCAM-1 camera which can be operated both in
Time-Delay Integration mode and in normal mode. Furthermore, DLR has provided
the software for image acquisition and quick look, and the routines for
automatic detection and astrometry of moving objects. The front-illuminated
CCD is a 2048x2048 LORAL chip with a pixel size of 15x15 æm (1".4 x 1".4 on the
sky), and covers an area of approximately 50x50 arcmin. The camera is equipped
with a precision shutter and is refrigerated by a two-stage cooling device,
where the primary stage is a Peltier cooler and the secondary one consists of
a closed-circuit liquid refrigerator. The achieved CCD operational temperature
is -63 deg. C. No filter is at moment available, but a filter wheel device could
be easily mounted if deemed scientifically productive. DA/OA Pd have provided
the acquisition computer and the secondary cooling stage. They are also
responsible for the mechanical adaptation of the telescope, for the
operations, for the data acquisition and analysis, and for the data
distribution and archiving. The system obtains regular data since February
2001. First results of the search will be provided.
Problem of asteroid absolute magnitude determination (Oral)
by BELSKAYA I.N. and SHEVCHENKO V.G., Astronomical Observatory of Kharkiv National University, Kharkiv (Ukraine)
At present the HG function is commonly used for the prediction of asteroid
absolute magnitude (Bowell et al., 1989). Analysis of the well-observed
magnitude-phase dependences for 35 asteroids of various types has shown that
the HG function overestimates absolute magnitudes for low albedo asteroids and
underestimates them for high albedo objects. The mean values of the opposition
effect amplitude calculated for the main asteroid classes can be used for more
accurate prediction of the asteroid absolute magnitude. The influence of
uncertainties in determination of asteroid visual absolute magnitude on
derived albedo is discussed. The parameters of magnitude-phase curves have
shown strongly dependence on asteroid albedo. It gives a possibility to
estimate asteroid albedo with an accuracy of 15-20% using its phase curve
alone. Asteroid albedos derived by photometric method for more than 100
asteroids have been compared with the IRAS and polarimetric albedos.
Bowell E.,Hapke B.,Domingue D. et al. 1989. In: Asteroids II,Univ. of Arizona Press, p.524.
Near-Earth Asteroids and Their Interest (Invited)
by BINZEL Richard, MIT (USA) and Paris Observatory (France)
Near-Earth objects (NEOs) are of intense scientific interest because this
population contains asteroids, active and extinct comets, and also meteorite
source bodies. Thus an understanding of near-Earth objects is essential for
resolving the relationships between asteroids, comets, and meteorites. Because
of their proximity to Earth, NEOs are also the smallest solar system bodies
that can be observed. As such, they display an array of physical properties
(unusual shapes, configurations, rotations) that have been previously
unobserved in physical studies of larger main-belt asteroids.
From Piazzi to the New Millennium (Oral)
(not received)
Asteroids density: an overview (Poster)
by BIRLAN Mirel, DESPA, Paris Observatory (France)
(not received)
Limited accuracy of asteroids track estimation at observations with CCD detectors. (Poster)
by BIRYUKOV Vadim (1) and RUMYANTSEV Vasilij,(2)
(1)Crimean laboratory of Sternberg Astronomical Institute of Moscow, Russia, Naunchny (Ukraine)
(2) Crimean Astrophysical Observatory (Ukraine)
Sometimes, "track objects" were detected by CCD together with point-like
ones during observations of minor planets. It is necessary to use the special
methods of data processing to estimate parameters of such objects.
The problem of accurate estimation of "fast" asteroids position has been
condidered from fundamental and applied points of view. First of all, the
limited astrometric estimates of asteroid tracks has been studying by means of
Cramer-Rao information inequality. Cramer-Rao theorem about minimum variance
bound fundamentally limit the accuracy of any estimate within a given
signal-to-noise ratio.
For many practical applications Maximum Likelihood Method gives
asymptotically unbiased estimate closed to the "Cramer-Rao Lower Boundary". We have been investigating the properties of this method as applied to the
problem of asteroid track astrometry. Moreover, the influence of the different
observational conditions was considered.
Numerous computer simulations show effectivity of Maximum Likelihood Method
for solution this problem. Test observations of some known fast moving
asteroids were carried out. Processing of this observations show good
agreement with theoretical approach.
Photometric observations of asteroids: rotational period, lightcurves, shape and spin axis determination (Oral)
by C. BLANCO, M.CIGNA, D.RICCIOLI, Dipartimento di Fisica e Astronomia
dell'Universita` di Catania (Italy)
A list of asteroids, observed during the numerous campaigns made at
Catania, is presented. The use of the collected data, depending on their
amount and distribution in phase and in longitude, allowed us to determine
their rotational periods, the B and V lightcurvesand the shape and the spin
axis determination.
Flux Preserving Regularization (FPR) method of restoration (Oral)
by BRATSOLIS Emmanuel and SIGELLE Marc, Ecole Nationale Superieure des
Telecommunications, Departement Traitement de Signal et des Images Paris (France)
The success of Richardson-Lucy (RL) algorithm is that it forces the
restored image to be non-negative and to conserve global flux at each
iteration. The problem with RL algorithm is that it produces solutions that
are highly unstable, with high peaks and deep valleys. Our aim is to modify RL
algorithm in order to regularize it while preserving positivity and total
photometry as far as possible. In this work we try to give a simple method of
spatial regularization deriving from RL algorithm in order to overcome the
problem of noise amplification during the image reconstruction process. It is
very important in astronomy to regularize images while having under control
their photometric behavior. We propose a new reconstruction method preserving
both the global photometry and local photometric aspects.
The Lowell Asteroid Database and its future (Invited)
by BOWELL E.L.G., ebowell@lowell.edu, Lowell observatory, Flagstaff, Arizona (USA)
I maintain a suite of web URLs (see http://asteroid.lowell.edu/ ) that
mainly involve applications of orbit research conducted in collaboration with
Karri Muininen and Jenni Virtanen of the University of Helsinki. The URLs,
most of which are updated daily, fall into four groups, three of which are
relevant to my presentation :
- Target generation URLs allow users to select asteroids that, for various reasons, are in need of astrometric observation. Prioritized lists may be generated, customized to users' observational resources and interests.
- Observational aids zero in on the observability of particular asteroids, as well as graphically displaying which regions of the sky the various NEO surveys have observed. Comprising this group of services are ephemeris generation, finder charts, observability plots, and a suggested observing strategy that will lead to an asteroid's numbering.
- There is catalog access to our asteroid orbital database "astorb.dat" (currently containing more than 140,000 sets of full--precision orbital elements and related data) and to the USNO--A2.0 star catalog.
Most of the anticipated work on the asteroid URLs will center around a new method of orbit computation that Virtanen, Muinonen and Bowell have been developing. Statistical Ranging of Asteroid Orbits (Icarus, in press) constitutes a completely general approach to orbit estimation that is particularly applicable to short orbital arcs, where orbit computation is almost always nonlinear. Orbits are selected in orbital--element phase space using Monte Carlo techniques, and the method can be applied to asteroids having only two observations. Among the applications we envisage presenting as web URLs are :
- Classification of orbit type} (e.g., Aten, Apollo) will comprise a probabilistic assessment, with or without incorporating a priori information on the (a,e,i) distribution of the known or debiassed asteroid population.
- Time dependence of ephemeris uncertainty, already readily calculable using linear theory for most "long"-arc (> 30days, say) asteroid orbits, is particularly relevant for short-arc orbits.
- Night-to-night linkage will allow users to determine the probability that asteroids observed over short intervals on two different nights are the same object, and to see how the probability depends on the total arclength and on the surface density of asteroids observed.
- A multi-dimensional all-sky map of moving objects will allow users to examine sky-plane uncertainty domains of known asteroids, making two-dimensional cuts according to magnitude limit, asteroid type, sky-plane motion, etc., and allowing zooming in to a chosen region.
Perturbations of Mars by the asteroids (Oral)
by BRETAGNON Pierre, Institut de mécanique céleste, IMCCE Paris Observatory (France)
The most perturbations of the planet Mars by the asteroids reach
amplitudes of about 13 km (with a 300 year period) and 5 km (with a 50
year period). The uncertainties of the masses of the asteroids limit the
quality of the ephemerides of Mars at several hundred of meters.
Accuracy of World positional CCD observations of the numbered minor planets in 2000 (Oral)
by BYKOV Oleg, L´VOV V. N., ISMAILOV I.S., SUMZINA N. K., Pulkovo Astronomical Observatory, St Petersburg (Russia)
Positions of the Numbered Minor Planets which have been sent by observers
to the Minor Planet Center in 2000 yr were automatically analysed by means of
calculation of (O-C) values with the help of the EPOS software package created
in Pulkovo Observatory. More then 593360 individual positions obtained by
professional and amateur observatories were taken into consideration. The
values of "Mean error of a single observation" were calculated for the most of
considered observatories during this period. These errors show the accuracy of
observations and processing for each telescope in the assumption that the
accuracy of the theory of motion of each Numbered Minor Planet is higher than
that of its observations.
The results of our analysis are given in the Tables which represent the
observatories and countries. Each Table contains the number of observed Minor
Planets, the number of analysed positions, the instrumental and accuracy
parameters and star catalog used for reductions.
Our investigation seems to be the first of that kind for the MPC data and
it could be continued in future.
CALCULATED by EPOS SOFTWARE (Pulkovo Observatory)
Accuracy estimation of the Numbered Minor Planet observations made by a world sky patrol in 2000.
| MPC code | Country Observatory | Diameter Focus | FOV | CCD scale, catal | Numbers of | Mean error of a single observation | |||
| planets | positions | RA | DEC | ||||||
| 704 | USA, Lincoln Lab | 1.0 2.2 | 90x90' | USNO | 14203 11794 | 432368 354850 | 0.51 0.54 | 0.51 0.55 | int ext |
| 699 | USA, LONEOS | 0.59 1.1 | 171x171' | 2.5" USNO | 7727 2169 | 61895 22323 | 0.59 0.72 | 0.32 0.36 | int ext |
| 608 | USA, Haleakala-NEAT | 1.2 | 90x90' | USNO | 3498 484 | 16976 4033 | 0.21 0.74 | 0.26 0.85 | int ext |
| 703 | USA, Catalina Sky Survey | 0.41 1.2 | USNO | 2151 138 | 10637 1156 | 0.42 0.34 | 0.44 0.51 | int ext |
|
| 691 | USA, Spacewatch | 0.88 4.6 | 32x32' | 1.1" USNO | 1898 635 | 10540 5261 | 0.20 0.34 | 0.21 0.31 | int ext |
| 106 | Slovenia, Crni vrh | 0.36 2.4 | 36x36' | 2.0" USNO | 531 129 | 2118 717 | 0.40 0.37 | 0.35 0.38 | int ext |
| 120 | Croatia, Vesnjan | 0.41 1.8 | 48x48' | 2.8" USNO | 257 188 | 1133 1306 | 0364 0.62 | 0.40 0.39 | int ext |
| 327 | China, Peking Obs. | 0.6 1.8 | 58x58' | 1.7" USNO | 221 61 | 982 467 | 0.28 0.31 | 0.30 0.31 | int ext |
| 49 | Sweden, Uppsala, | 1.0 | 35x35' | 1.0" USNO | 191 53 | 866 368 | 0.20 0.47 | 0.22 0.29 | int ext |
| 300 | Japan, Bisei Center | 0.50 1.0 | 60x120' | USNO | 155 59 | 750 407 | 0.41 0.36 | 0.32 0.21 | int ext |
| 46 | Czech Rep., Klet | 0.57 3.0 | 16x10' | 1.2" USNO | 35 5 | 142 25 | 0.22 0.16 | 0.19 0.09 | int ext |
© Pulkovo Observatory, O.P.Bykov and others
P.S."Int" is an interior error obtained as a result of processing single night observations, "Ext" is an external error calculated as a result of processing several nights close positions.
Kuiper Belt Objects photometry and position measurements with BTA - 6m telescope (oral)
by BYKOV Oleg, MASLENNIKOV K. L., GNEDIN Yu. N., Pulkovo Astronomical Observatory, St Petersburg (Russia)
We have carried out BVRI photometry and positional measurements for 16
transneptunian (Kuiper belt) asteroids (KBOs) with BTA-6m telescope (Special Astrophysical Observatory, North Caucasus, Russia).
Two color types for the asteroids were revealed according to their reflectance spectra at red
wavelengths. In particular, a group of KBOs with a pronounced maximum of normalized reflectance near 7000 A was noticed.
In this group, asteroids display on average smaller eccentricities and inclinations, compared to those
with "flat" normalized reflectance. Suggestions are made concerning the possible reasons for these color differences.
Astrometic positions of these KBOs were calculated also with good accuracy. In addition, several unknown
Main belt asteroids were detected in the course of the observations and their
colors were directly compared with those of the KBOs.
Single night positional CCD observations of unknown celestial bodies: what's a problem ? (Poster)
by BYKOV Oleg, Pulkovo Astronomical Observatory, St Petersburg (Russia)
Mass positional CCD observations of celestial bodies moving against the background of reference stars are characterised by a high accuracy,
a large efficiency and unlimited dencity of distribution of observed positions along
of a short arc of celestial sphere. Now these CCD- observations have a good star and orbital catalogues services. There are also various astronomical
softwares for the fast processing of modern CCD asteroid observations. In these circumstances the observer himself can identify all known
celestial objects which could be seen in his telescope field of view during a time of observations.
It may be done by means of preliminary calculation of
catalogue positions for all known objects at given UT moment. After this identification, initial circular or sometimes elliptical orbits for the
unknown asteroids having several positions per night may be calculated with the help of the Apparent Motion Parameters Method (AMP-method) created by Dr.
A.A.Kisselev and others in Pulkovo Observatory. The AMP-method is a further development of the Classical Laplacean Method for preliminary orbit
determination. One ought to remember that the AMP-method requares three or more observed positions during a single night.
The AMP-method was successfully applied by author for calculations of initial orbits of the Near Earth Asteroids, Kuiper Belt objects and Artificial
Earth Satellites with the use of short arc positional observations when the parameters of the Apparent Motion (namely: values of angular velocity and its
position angle, angular acceleration and curvature of trajectory) or the first and the second derivatives of spherical coordinates of observed objects were
accurately obtained. Our experience shows that orbit calculated with the AMP-method is very close to the real object's orbit and it may be used for a
searching unknown object in the first or second week after its discovery. Author believes that CCD observations of the unknown asteroid obtained by a
single observatory during one night allows an observer himself to determine of asteroid orbit with the use of AMP-method for the continuation of its
observations and rediscovery of this object in near future. Thus, a problem of "a single night close observations" may be solved for the Minor Planet Center
and each asteroid's observer.
New method for asteroid identification with the use of Pulkovo Apparent Motion Parameters (Poster)
by BYKOV Oleg, KOMAROVA N. O., Pulkovo Astronomical Observatory, St Petersburg (Russia)
Modern CCD observations of asteroids give us several close accurate positions distributed along a short arc of celestial sphere. Usually such
coordinate set contains 3 -5 asteroid positions per night. It's sufficient for a calculation of the first derivatives of asteroid coordinates or the angular
velocity and position angle of asteroid motion. Together with traditional data for an identification of the asteroids, i.e. the normal places, additional
information about parameters of asteroid motion may be used in the process of the fast and reliable identification of the same object during a long time
interval after the last its observation.
On the base of original Pulkovo EPOS Software created by Dr. L´vov and his
colleagues and Apparent Motion Parameters Method (the APM-method) developed by Dr.Kisselev and others we had elaborated new method for asteroid
identification by means of the first and second derivatives of spherical coordinates or with the use of anagular velocity and acceleration, positional
angle and curvature of asteroid motion. Our method was tested with the vast examples and may be recommended to the real identifications as in the Minor
Planet Center as also in the professional and amateur observatories.
Triumph of the Laplacean ideology for preliminary orbit determination in the CCD epoch (Poster)
by BYKOV Oleg, Pulkovo Astronomical Observatory, St Petersburg (Russia)
The epoch of supremacy of CCD technique allows us to elaborate the new approach to the problem of observations and identification of any celestial
body moving on the background of stars. The fundamental base for such approach is the Classic Laplacean Method of initial orbit determination and its
development.
Due to the accurate star catalogues and computers one can calculate several astrometric positions of any celestial object and its angular velocity by
means of statistical processing of the set of object's coordinates almost in a real-time of CCD observations. These four parameters (namely RA, DEC, dRA/dt
and dDEC/dt) are usually enough to determine its circular or parabolic preliminary orbit which may be useful for identification of observed object or
for ephemeris service during several close nights or weeks. In this manner we can investigate each CCD frame for the search of small Solar system bodies.
The algorithms and software were developed in Pulkovo observatory for the fast analysis of any CCD frame where the moving celestial objects were
detected. Due to this approach we can get new information as "by product" of dominating astrophysical CCD observations.
Eight years of observing asteroid approachs to stars (Oral)
by CASAS Ricard, Agrupacio Astronomica de Sabadell (Spain)
Since 1993 our group has observed many approachs of asteroids to stars to determine the minimum distance. On two occasions we have also observed an
occultation associated with the close approach during the observations and have thus been able to test our method.
Agrupacio Astronomica de Sabadell: Our work in the field of the asteroids (Poster)
by CASAS Ricard, Agrupacio Astronomica de Sabadell (Spain)
The Agrupacio Astronomica de Sabadell is Spanish amateur association with 800 members. Some members work in different field of asteroidal studies:
occultations, approachs, astrometry,.. with the association's observatory, sited in Sabadell. In these studies, one goal was the discover of the asteroid 13260 Sabadell.
The Crimean CCD telescope for the of asteroid observations (Poster)
by CHERNYKH N.S., RUMYANTSEV V.V., Crimean Astrophysical Observatory, Nauchny (Ukraine).
Old 64-cm Richter-Slefogt telescope (F=90 cm) of the Crimean Astrophysical Observatory was reconstructed and equipped with the St-8 CCD camera received
from the Planetary Society for the Eugene Shoemaker Near Earth Object Grant. First observations of minor planets and comets were made with it. The CCD
matrix of St-8 camera in the focus of our telescope covers field of 52'.7 x 35'.1. The 120 - second exposure yields stars up to limiting magnitude of
20.5m with S/N=3.
According to preliminary estimations it is possible to cover during the year the sky area of 550 sq. deg. with threefold overlapping and to open up to
3500 main belt asteroids and 2 Near-Earth Asteroids. An automation of the telescope can increase the productivity up to 20000 sq. deg. per year. The
software for object localization, image parameters determination, stars identification, astrometric reduction, identification and catalogue of
asteroids is worked up. The first results obtained with the Crimean CCD 64-cm telescope are discussed.
Ceres : A true "Minor" Planet (Oral)
by CHRISTOU Apostolos, Armagh Observatory, Northern Ireland (United Kingdom)
The asteroids (1) Ceres and (4) Vesta are two of the most massive objects in the asteroid belt. As such their perturbing effects on the motion of other
asteroids serves as a proxy for determining their masses. Recently, it has been shown that Ceres (and possibly Vesta) are capable of trapping and
maintaining other asteroids as their co-orbitals in the same manner that the planets Jupiter and Mars hold their respective Trojan families (Christou,
A&A, 2000). One asteroid in particular, (1372) Haremari, is probably co-orbiting with Ceres at the present time. We present the main features of
these objects' motion and we discuss the possible existence of other members of this dynamical group (including distant retrograde asteroidal satellites),
their origin and distribution in the vicinity of large asteroids and their relevance to the asteroid mass determination problem.
Shape Determination of the Asteroid (6053) 1993 BW1 (Poster)
by DURECH Josef, Astronomical Institute, Charles University, Prague (Czech Republic)
A method for determining asteroid shape from its lightcurves is presented. Asteroid shape was approximated by a polyhedral model made of 1000 triangular
facets. Rotation around the axis of maximal momentum of inertia and the uniform albedo were assumed. A trial-and-error method was used to derive the
shape which gives the best possible fit between observed and computed lightcurves. There are two different shapes for two pole directions (180 deg,
6 deg) and (354 deg, -14 deg) in ecliptic coordinates. An estimation of the Hapke's parameters describing the surface optical scattering properties is
also given.
On the light curve of the Amor asteroid (719) Albert (Poster)
by ELST Eric W., Royal Observatory, Uccle (Belgium)
(not received)
Impact of the dynamical perturbations of the main belt asteroids on planetary ephemerides : Why is it important to have accurate determination of
the main belt asteroids size and shape. (Oral)
by FIENGA Agnès, Institut de mécanique céleste (IMCCE/ Paris obs.) (France) and Jet Propulsion Laboratory (USA)
In this presentation, I will present new results obtained at JPL on testing how the main belt asteroids could perturb the ephemerides of Mars and the
Earth and at what level. A survey of several masses, sizes and shapes estimations was done and the impact of these severel determinations on the
ephemerides was computed. Monte Carlo simulations was also performed to estimated the sensiblity of the DE405 ephemerides to the change of asteroids
masses. I will conclued in stressing the fact that in the future, we will need more and more accurate ephemerides of Mars due to a huge number of spacecraft
missions and the improvement of these ephemrides are closely correlated to improvement of our knowledge of the shape and size of more and more asteroids.
PRIAM : a new efficient astrometric software (Oral)
by FIENGA Agnès 1,2, BERTHIER Jérôme 1
1 Institut de mécanique céleste (IMCCE/Paris obs.) (France)
2 Jet Propulsion
Laboratory (USA)
We will present a new IMCCE astrometricsoftware called PRIAM. The software was set up by J.Berthier and I as a very accurate astrometric toolfor the
preparation of stellar occulations as well as astrometry of solar system objets, and stellar objets. We will present some major results we obtained in
the past and made some recommandations.
The discovery of Ceres by Piazzi in 1801 (Invited)
by FODERA Giorgia, Faculty of Sciences of Palermo University, Palermo (Italy)
The discovery of Ceres by Giuseppe Piazzi on January 1st 1801 soon followed (March 28, 1802) by that of Pallas by Olbers was immediately perceived by
William Herschel as a potentially fruitful field of investigation of a new species of celestial bodies, with which hitherto we have not been
acquainted. In the light of the fairly recent surge of studies and wealth of results on the small bodies of the solar system, Herschel's words sound
prophetical.
In this paper I shall address the circumstances of the discovery of Ceres, the reaction of the astronomical community at the
announcement of the discovery, and the evolution (if any) of thought about the nature of these bodies after the discovery of Pallas, Juno and Vesta.
Meteorite-asteroid connection: Mineralogy of terrestrial meteorite collection may differ from Martian one (Oral)
by GOLUBEVA Larissa, Shemakha Astrophysical Observatory, Azerbaijan Academy of Science, (Azerbaijan)
AA-asteroids from the Apollo-Amor dynamic groups are candidates for the role of the last parent bodies of meteorites (asteroid bits falling on the
Earth). This fact is in accord with astrophysical data, which give evidence of the asteroid and meteorite spectral characteristics closeness [1,2]. Besides,
there are gaps in the AA-asteroid perihelion distribution on the just heliocentric distances where terrestrial planets move [3]. Hence, the planets
cleared the space on its own way scooping out and perturbing asteroids and their bits when approaching by them.
Thus the questions occur - what asteroid main belt region might previous meteorite parent bodies be in? (I.e. those are the asteroids that can be
considered as AA-asteroid parent bodies). Is there such information in modern astrophysical databases?
Probable quantity of the AA-asteroids is estimated at several hundreds or thousands of bodies. Only several dozens of them have optical taxonomy. Here
we are limited by the S-asteroid data because they are the most numerous in the considered sample. We applied statistical methods of investigation to
color-index u-x for S-asteroids from 8-color survey [4].
Color-index u-x correlates with the absorption band position at 950 nm in S-asteroid spectra [5]. Consequently, the comparison of asteroid spectra by
their color-indexes u-x has a mineralogical mean. The close values of u-x indicate to approximately equal surface mineral composition of the compared
S-asteroids.
Color-index u-x shows the interesting a distribution on semimajor axes (a) and perihelion distances (q). For main belt S-asteroids (a = 2.2-3.5 a.u.) u-x
decreases with increasing (a), and on the contrary, u-x decreases with decreasing (a) for asteroids outside of main belt (a<2.2 a.u.). When
changing (q) color-index u-x behaves in a similar manner. U-x increases with increasing (q) for asteroids outside of main belt (q<1.8 a.u.), and for
main belt asteroids (q>1.8) u-x begins to decrease when increasing (q). All the obtained regressions are statistically significant. We obtained the
following results using t-statistics of u-x mean values.
i) There is statistically significant distinction between mean color-index
u-x for near-Earth asteroids (from AA-asteroid dynamical group) and near-Mars asteroids (from dynamical group of Mars-crosser asteroids). ii) There is no
statistically significant distinction between mean color-index u-x for NEA and main belt asteroids in heliocentric distances 2.6-3.2 a.u. iii) There is no
statistically significant distinction between mean color-index u-x for NMA and main belt asteroids in heliocentric distances 1.8 -2.6 a.u.
From here, the following conclusions may be done. Probably, some part of AA-asteroid population is supplemented by the asteroids situated in the outer
zone of main belt (2.6 < a < 3.2 a.u.). Whereas MCA population is supplemented by the asteroids situated in the inner zone of main belt (1.8 < a <2.6 a.u.).
The mechanism that transforms the orbits of main belt asteroids into orbits crossing with the Earth and Mars orbits is, most likely, resonant disturbance of orbital
elements of asteroids falling for some reason or other in the Kirkwood gaps. Sooner or later Earth and Mars scoop out such asteroids clearing in this way the Kirkwood
gaps [6]. Since as we obtained mean values of color-index u-x are different for S-asteroids closing to the Earth and Mars orbits, then the mineral characteristics
of meteorite material that accumulates on these planet surfaces must differ.
References :
1.R.P.Binzel et al//Science.1996.Vol.273. P.946.
2. D.I.Shestopalov, L.F.Golubeva//Astron. Vestn.1992. Vol.26. P77 (in Russian).
3. Simonenko
A.N//Lett.in Sov.Astron.J.1977. Vol.3 .P.30 (in Russian).
4. B.Zellner et al//Icarus.1985. Vol.61. P.355.
5. D.I.Shestopalov, L.F.Golubeva //27th
Lunar and Plan.Sci.Conf.P1303.
6. S.I.Ipatov. Migration of Celestial Bodies in the Solar System, Moscow.2000.320 p.(in Russian).
Asteroid photometric center determination. (Poster)
by GRYNKO Yevgen and SHKURATOV Yu., Kharkov Astronomical Observatory (Ukraine)
Due to irregular shape of minor planets an error arises at precise measurements of asteroid position through astrometric observations. The
photometric center of asteroid does not always coincide with the real position of asteroid geometric center. It is caused by the revolution of asteroid on
its axis and by the variations of phase angle and rotation axis orientation. To investigate this error we used computer experiments. Our experiment
simulates illumination and observation of asteroid revolving on its axis. At first we generate a model of a body with irregular shape and with adjusted
degree of irregularity. It is represented in the computer memory as an arbitrary polyhedron, i.e. as the succession of triangular facets attached to
each other. Then a beam of rays comes in the body surface at the known illumination/observation geometry. One can put a normal to each facet and
determine local angles of incidence and emergence and to apply some indicatrix for surface element. Lommel-Seeliger light-scattering indicatrix was taken,
but it should be emphasized that any other indicatrix could be involved in the analysis. Ray tracing procedure is realized to determine the part of the body
which is illuminated and visible simultaneously, i.e. to derive the law of brightness distribution over asteroid. Our model allows derivation of
brightness distribution law for a body with any shape and with any degree of deviation from spherical shape.
After that we can calculate photometric center at the given phase of rotation averaging out over visible elements taking into account the
contribution of each element to the reflected flux. The coordinates of the real center of asteroid can also be easily determined. In this way it is
possible to track how the photometric center moves about geometric one as model parameters change. Through modeling we obtained a number of time
dependencies and diagrams of photometric center dispersal for a set of phase angles and for different values of irregularity parameter at arbitrary
rotation axis orientation.
Orientation parameters of reference frames as obtained from photographic observations of the minor planets at Nikolaev astronomical observatory (Oral)
by GUDKOVA Ludmila, Nikolaev Astronomical Observatory (Ukraine)
During 1961-1997, 2328 photographic observations of 12 selected minor planets (SMP) were obtained at Nikolaev astronomical observatory. The
observations were taken with the zonal astrograph (ZA/ D=120mm, F=2044mm, field: 5øx5ø) for determination of the corrections to the fundamental
catalogue zero-points. The reduction of these observations to equatorial positions has been made using the reference stars from Yale, SAO and AGK3
catalogues (FK3/B1950.0 and FK4/B1950.0 ). After the PPM catalogue became available new reduction was realised to the FK5/JD2000.0 system using the PPM
reference stars. And after publishing the Hipparcos and Tycho catalogues we reduced the Nikolaev observations to the new International Celestial Reference
Frame (ICRF/JD2000.0) using dependences and reference star positions from Hipparcos and Tycho catalogues (HT). Because the accuracy of the Tycho proper
motions is generally too low to calculate positions at other epochs with sufficienty accuracy the proper motions were taken from ACTRC catalogue. The
mean position accuracy of the 12 SMP observed with the ZA was obtained as rms scatter of (O-C) differences from the mean values of the (O-C) averaged over
36-year interval of the observation time and it is ñ0.18" in the FK5 and ñ0.15" in ICRF systems. (O) is the ZA positions and (C) is the positions
computed with using the DE200/LE200 ephemeris.
These observations have been used to determine the orientation parameters (ex, ey, ez ), the rotation angles (wx, wy, wz ) and displacement of the
equators (Dd0 ) of the FK5 and ICRF catalogue systems with respect to the DE200/LE200 dynamic system of reference. The values of the orientation
parameters and their time changes were obtained for epoch JD 2445600.5 and are given in mas for e and mas/yr for w.
| FK5-DE200/LE200 ex = 13 ñ 19, wx = 2.4 ñ 0.6 ey = 15 ñ 20, wy = 0.0 ñ 0.7 ez = 42 ñ 28, wz = 1.6 ñ 1.2 |
ICRF-DE200/LE200 ex = 8 ñ 16, wx = 1.3 ñ 0.5 ey = -20 ñ 16, wy = -0.4 ñ 0.6 ez = 42 ñ 23, wz = 1.6 ñ 1.0 Dd0= 59 ñ 4 |
The same calculations were peformed for the each SMP separately. As it was found the dispersion of the ICRF orintation parameters with respect to the dynamical system is considerably less than dispersion of the mutual orintation parameters for the FK5 and DE200/LE200 systems. The recearch of the (PPM-HT) differences in coordinate positions of the reference stars used for the reduction of the SMP observations showed the strong correlation between the FK5 orientation parameters (ez and Dd0) and the mean values of the (PPM-HT) coordinate differences of the reference stars avaraged in the bound observed of the each SMP. This fact can be explained by the influence of the zonal systematic errors of the PPM reference catalogue on determination of the mutual orientation parameters between of the FK5 and DE200/LE200 systems.
Possibilities of the Bulgarian national observatory for astrometric
and photometric observations of asteroids (Oral)
by IVANOVA Violeta and APOSTOLOVSKA G., Institute of Astronomy, Bulgarian Academy of Sciences, Sofia (Bulgaria)
The equipment possibilities for observations of asteroids and comets of the Bulgarian National Observatory - Rozhen, are presented. Some results of the
observations of asteroids (astrometric since 1983 and photometric since 1993) and their accuracy are discussed.
Asteroid models from disk-integrated photometry (Invited)
by KAASALAINEN Mikko, Observatory, Univ. Helsinki (Finland)
I present an overview of the methods for determining the shapes, rotational states (including precession), and scattering properties of asteroids. Modern
optimization methods render lightcurve inversion a well-posed problem; models obtained for, e.g., Eros, Gaspra, and Golevka agree very well with the data
from NEAR and Galileo missions and radar observations. Detailed models can be made of both main-belt and Near-Earth asteroids. I present some recent results
for selected asteroids, and discuss thefuture prospects of the inversion of general disk-integrated data.
What can we learn from the lightcurves of freely precessing asteroids?
by KRYSZCZYNSKA Agnieszka, KWIATKOWSKI T., BREITER S. Astronomical Observatory of A. Mickiewicz University, Poznan (Poland)
This paper presents results of modelling light variations of freely precessing asteroid, assuming its ellipsoidal shape and a geometric light
scattering law. The method is based on numerical integration of Euler equations combined with the explicit expression of an asteroid's brightness as
a function of Euler angles. We discuss what parameters of the asteroid rotational state can be obtained based only on their lightcurves.
Photographic and CCD observations of Minor Planets from Valencia Observatory (Oral)
by LOPEZ GARCIA Alvaro, Astronomical Observatory, Valencia (Spain)
Valencia Observatory holds a program of bright minor planets observations since 1985, in collaboration with Institute of Applied astronomy (IAA) of
St.Petersburg, Russia. Nearly 1000 film plates were taken with a 6 inches Grubb refractor from Observatory building in Valencia until the program was
discontinued in January 1998. Special hardware and software was developed for automatic measuring and reducing of plates. Since May 1998 Valencia
Observatory holds a new 30-20 cm double refractor at the 'Astronomical Centre of Alto Turia' (CAAT), 110 km from Valencia. New photographic devices and an
AP10 CCD will allow us to carry on regular series of minor planets observations. A second 50 cm reflector will be put at work in the next future.
Minor planets astrometric and photometric observations will be the main work done with these instruments, that are shared with amateur association AVA and
will be offered to other professional and amateur groups in future common observing programs.
On the displacement of asteroid photocentre due to surface scattering (Poster)
by LUPISHKO Dmitrij F., TUNGALAG, N., SHEVCHENKO, V. G. , Astronomical Observatory of Kharkiv National University (Ukraine)
The recent increase of the accuracy of ground-based astrometric observations of asteroids due to the application of CCD-detectors and the use
of highly accurate HIPPARCOS asteroid data make essential taking into account the asteroid displacement caused by nonuniform brightness distribution on
asteroid apparent surface (limb-darkening, albedo distribution, etc). For this purpose, the numerical modelling of asteroid brightness distribution for
different scattering laws (Lambert, Lommel-Seeliger, Hapke, theoretical and empirical Akimov laws) was carried out. The numerical photometric model of an
asteroid which provides the arbitrary i) asteroid shape, ii) albedo distribution on the surface and iii) scattering law was used. The triaxial
ellipsoid with semi-axis ratio a:b:c = 2:1.4:1 was chosen as a figure of the model. The calculations were carried out for the equatorial aspect of an
asteroid. In this case, the point on the photometric equator of apparent asteroid disk, on the left and on the right of which the integral brightnesses
are equal, determines the photocentre position.
It was shown that the photocentre displacement essentially depends on the
asteroid shape, phase angle and light scattering. Its value can reach (0.3 - 0.4)R, where R is the asteroid angular radius. For the main-belt asteroids
with angular sizes > 0.1" the displacements can reach the value of 0.02² and even more (up to 0.06-0.10" for the largest asteroids 1 Ceres, 2 Pallas, 4
Vesta and 324 Bamberga). For the NEAs the photocentre displacements can reach large values because of the large values of phase angles. For example, the
Apollo-asteroid 4179 Toutatis in December of 1992 approached the Earth to 0.024 AU, and its angular size and phase angle were equal to 0.2"; and 100°,
respectively. In this case, the photocentre displacement was equal to 0.07". Such values exceed the accuracy of space-based astrometric measurements
(0.015-0.020") and of the modern ground-based ones (or are compared with them) [1,2]. Therefore, taking them into account can noticeably improve the accuracy
of asteroid position determination.
The practical recommendations on the determination of the asteroid photocentre displacements are given.
1. Hestroffer D., Viateau B., Rapaport M. Astron. Astrophys. 1998, V. 331, P. 1113-1118.
2. Owen Jr.W.M., Synnott S.P., Null G.W. Modern astrometry
and astrodynamics. Proceed. of Int. Conf. Vienna (Austria) 25-26 May, 1998. R.Dvorak, H.F.Haupt, K.Wodnor (Eds.), 1999, P. 89-101.
What do the physical properties of Near-Earth Asteroids tell us on their sources of origin (Oral)
by LUPISHKO Dmitrij F.1, LUPISHKO T. A.1, DI MARTINO, M.2
1 Astronomical Observatory of Kharkiv
National University (Ukraine)
2 Astronomico Osservatorio di Torino, Italy
It is generally recognized that main-belt asteroids (MBAs) and the nuclei of extinct comets are two main sources for the near-Earth asteroids (NEAs)
replenishment. Theoretical studies of NEA dynamics and numerical modelling of their orbital motions showed that the so-called resonance mechanism for
supplying NEAs is quite sufficient to sustain this population. The comparison of physical properties of NEAs and MBAs (and partly of comet nuclei) aimed at
understanding what the physical properties of NEAs can tell us about their sources of origin was carried out in this paper. The principal results of such
comparative analysis can be reduced to the following: the small sizes of NEAs, almost the same variety of their taxonomic classes and mineralogy,
predominance of differentiated assemblages among them, approximately the same shapes and rotation, optical properties and surface structure as compared to
those of MBAs, all these clearly indicate that the main asteroid belt is the principal source of NEA, and comet nuclei contribution to the total NEA
population does not exceed 10%. The NEAs 2100 Ra-Shalom, 2101 Adonis, 2201 Oljato, 2212 Hephaistos, 3200 Phaethon, 3552 Don Quixote and 4015
Wilson-Harrington are the most probable candidates for the cometary origin.
The amateur networks of asteroidal observations (Invited)
by MANEK Jan, Stefanik Observatory, Praha (Czech Republic)
(not received)
K.E. Edgeworth and TNOs (Oral)
by McFARLAND John, Armagh Observatory (Northern Ireland, UK)
An overview of Kenneth Essax Edgeworth's views on the origin and development of the solar system is presented. Particular reference is made to
his pre-Second World War writings on the trans-Neptunian region.
CCD photometry of asteroids carried out at Poznan Observatory (Oral)
by MICHALOWSKI Tadeusz, Poznan Astronomical Observatory (Poland)
In 1997 we started photometric observations of asteroids using a 0.4-m telescope equipped with a KAF400 CCD camera. This campaign has been carried
out in order to enlarge the number of the asteroids with known spin vectors and shapes.
Detection of Asteroid Companions by Astrometric Methods (Poster)
by MONET Alice K. B., MONET David G., US Naval Observatory Flagstaff Station (USA)
Three years ago, we reported on results of a study of the detectability of astrometric ``wobble'' in the orbits of binary asteroids (A.Monet and D.Monet,
1998, BAAS, 30, 3, 1144.) At that time, only one asteroid companion had been detected. In the ensuing years, several more asteroid
companions have been directly imaged, primarily from the ground using large telescopes with adaptive optics. Although the numbers are still small, these
detections have led to better physical models of asteroid structure, evolution, and collisional histories. The simple fact that asteroid companions
are being identified every few months, now that sufficiently high optical resolution is widely available, suggests that duplicity is rather common. The
question addressed in this poster is how to design an astrometric survey to detect asteroid companions, using smaller aperature (< 2-meter) telescopes,
such as the automated, 1.3-meter telescope, just now nearing completion at the USNO Flagstaff Station.
Photometric Study of Outer Solar System Bodies (Oral)
by Peixinho, N.1,2, Doressoundiram, A.1, Barucci, A.1
1 Observatoire de Paris-Meudon 2 Centro de Astronomia e Astrofisica da Universidade de Lisboa
1 Observatoire de Paris-Meudon
2 Centro de Astronomia e Astrofisica da Universidade de Lisboa
Trans-Neptunian Objects (or Edgeworth-Kuiper Belt Objects) and Centaurs are very faint and elusive objects, and a careful data reduction has to be
performed. Growthcurve correction is the most common technique applyed in order to optimise data extraction.
At Paris-Meudon Observatory a multicolour photometric survey is being dedicated to these objects which might contain important clues on the
formation of the Solar System. A large colour diversity is shown raising questions on their nature, formation processes and physical and chemical
evolution. Some results of this survey are presented and discussed.
Estimating masses of asteroids (Oral)
by KRASINSKY G.A., PITJEVA E.V., VASILYEV M.V., YAGUDINA E.I. Institute of Applied Astronomy of Russian Academy of Sciences (IAA RAS), St. Petersburg (Russia)
Comparison of masses of asteroids derived by dynamical methods (mainly from mutual perturbations of pairs of asteroids with close encounters) with
estimates obtained by astrophysical methods is carried out. It is shown that the asteroids with masses > 10-12 of solar mass affect the orbit of
Mars on the already reached high level of accuracy of measurements of ranging to the martian landers Viking 1, 2 and Pathfinder. It appears that the
dynamical methods based on the ground astrometry, and the astrophysical methods are complimentary: the first ones give satisfactory results only for
several biggest asteroids, but fails on this level of accuracy for a great number of small asteroids, while astrophysical methods allow to estimate
reliably the masses about 2000 small asteroids but cannot be applied to the biggest ones.
An attempt is undertaken to extent the list of 300 asteroids from which the perturbations have been taken into account in the adopted DE403/DE405
ephemerides. Several tests are tried varying the total number of perturbing asteroids (up to 351) in the planetary ephemerides developed in IAA in which
the perturbations of asteroids are computed rigorously by simultaneous numerical integrations of the equations of motions of the major planets and
the asteroids. It appears that the astrophysically determined masses of some of the biggest asteroids which have not be accounted in DE403/DE405
ephemerides, are too large and inclusion of these asteroids to the dynamical model seriously deteriorates fitting of the measurements of ranging to the
martian landers.The common effect of other asteroids (apart of those which are directly integrated) has been modelled by potential of a circular ring
in the ecliptical plane; the mass of the ring has been estimated with the value about 500*12-10 MSun and uncertainty about 10 percent. For the mean radius
Rring we obtained 2.80 AU with 3 percent of uncertainty. In Appendix a list of derived masses for 357 asteroids tested by processing
of the lander measurements is given.
The precession of asteroid satellite (Poster)
by PORTYANKINA G., ALEKSANDROV Yu. V. , Kharkov Natonal University, Department of Astronomy (Ukraine)
To describe the motion of a satellite (both artificial and natural) of the asteroid it is desirable to take into account the real shape of the primary.
It can be easily made in each particular case, when the real shape of considered asteroid is well determined. But for the analysis of the
lightcurves of binary asteroids the real shape of which is unknown some rate of standartisation is necessary. The typical shape of asteroids is expected to
be a triaxial ellipsoid with the ratio of half-axes a:b:c = 2: :1, because the experiments on impact fragmentation of bodies speak in favor of this and the
estimation of value a·sini/b using mean amplitude magnitude of asteroid lightcurves (i is the corner between the rotation axis of an asteroid and the line of sight) is in qualitative agreement with this conclusion. In addition
asteroids are considered to be homogenous bodies. The approach of two fixed centers appears to be a good approximation to describe the dynamics of binary
asteroids in this case.
In this work the classical problem of two fixed centers was used as the basis for modeling the motion of the satellite in the gravitational field of a
very oblate asteroid. At first the task about accuracy of this approximation is considered. The comparison between the gravitational field of asteroid
(with the shape mentioned above) and the field of the gravitational doublet was made on the surface of asteroid. The error arising at such approximation
is found to be great only when the asteroid has a big oblateness. For example at oblateness ≈1:5 (in this case the eccentrisity of polar section of asteroid
is equal to 0.98) the error comes up to 37%. It should be noted that the error of approximation decreases with increasing of the distance from the surface of
the body, for example, at polar axis at r = 2ñ and oblateness ≈1:5 the error is equal only to 8% and at r = 3ñ - only 1%.
The next task was to estimate limits in wich it is possible to use the approach of classical description of the motion in the field of oblate planet.
Under the classical description we imply the description in terms of precession of the line of nodes and precession of the line of apsides. The
computer modeling of the motion of satellites is used to compare the classical approach with the approach of two fixed centers. The results are the
following:
The description in terms of precession is legal when the eccentrisity of polar section of the primary is smaller than 0.6. But even in these limits the
behavior of the satellite is different whether you consider it in the problem of classical precession or in the problem of two fixed centers. In the last
case the influence of primary oblateness on satellite motion is noticeably smaller than in the first one.
When the eccentrisity of polar section of the primary is 0.6 and larger the
motion of satellite can not be described in the terms of precession because of some extent of chaos in the motion.
All achieved results testify that the problem of two fixed centers gives more accurate description of the motion of asteroid satellite in comparison
with the description in terms of precession of line of nodes and precession of line of apsides. At the same time in this problem the equations of motion are
integrated in quadratures and that is why it can be used as a model for determining the physical properties of binary asteroids when analysing of their lightcurves.
Hegel and the discovery of minor planets (Oral)
by RAPAPORT Michel, Bordeaux Observatory (France)
En mai 1801 Hegel soutient sa thèse de philosophie à Iéna, sur le mouvement des planètes. Dans cette thèse, l´auteur dé;veloppe ses idées sur la physique
et la mécanique, et explique pourquoi il n´est pas utile de chercher de nouvelles planètes entre les orbites de Mars et Jupiter. Je présenterai
l´argumentation du philosophe en essayant de la situer dans son contexte.
On the ephemerides of minor planets for which new observations are required (Oral)
by ROSAEV A.E.(1) and PEROV N.I (2)
(1) FGUP NPC Nedra, Yaroslavl, Russia, (2) Yaroslavl
State Pedagogical University
The systems of minor planet's orbital elements are permanently improved due to new observations. So, each system of elements E(t)= Eo(t) depend from N
observation, where N=N(t)- permanently increase with time. It may be expected, Eo(t) streams to Er , if t increased. Here Er - the "real" elements, depended
only from planetary perturbation and free of observation errors. On the other side, we can to calculate E(t)=Ec (t) at each moment, by using E(t0) system of
orbital elements as a basic. After that, we can calculate (O-C)E =Ec- Eo at each moment t. This value is a characteristic of the accurance of the system
of elements Eo(t) at moment to.
So, (O-C)E value may be used for select a minor planet's orbits, for which the improving the system of elements required. Really, such calculations was
developed, using all updates of minor planets orbital elements at Lowell observatory at 1999-2000 year and two particular systems of elements in 1997
and 1998 years. We use integration with "Ceres" (1000 first minor planets, full perturbations, 1997-2004 years, step 40 days). There are 6-8 points for
comparison for each minor planet. In result, we obtain a list of minor planets with large (O-C)E . The search and discovery of unknown bodies of the Solar
system related to asteroid danger problem as well as studying of fundamental properties of the planetary system.
One of the possible methods of finding new celestial bodies may be based on the integrable problems of celestial mechanics. It is interesting, to our
mind, to find regions of increased concentrations of asteroids, based on the solution of restricted planar 3- body problem. It is well known, the stability
of these solutions.
As the result of this investigation, we have calculated coordinates of the regions of increased concentrations of asteroids for the systems:
Sun-Mercury-minor body 1,2; Sun-Venus-minor body 3,4; Sun-Earth-minor body 5,6; Sun-Mars-minor body 7,8; Sun-Jupiter-minor body 9,10; Sun-Saturn-minor
body 11,12; Sun-Uran-minor body 13,14; Sun-Neptun-minor body 15,16; Sun-Pluto-minor body 17, 18. The according ephemerides have been calculated.
Parameters of apparent motion of asteroids which collide with the Earth (Poster)
by RUMYANTSEV Vasilij, Crimean Astrophysical Observatory (Ukraine)
This work is dedicated to the observable and dynamic features of Earth-crossing asteroids for the last several weeks before their impact.
Orbits, bringing to such collision, were defined on the base of modeling from the position and velocity at a moment of collisions. From the received
ensemble of orbits only elliptical orbits with direct motion were considered. Analysis of circumstances of approaching has show that velocity of visible
motion of such asteroids for a week before the collision, does not exceed a value of 15 arcsec per hour, and even is vanishing little for some approach
directions. It is two or more times slowly than visible velocities of main belt asteroids in opposition. For 300 m asteroid a brightness for 2 months
before the collision ranges from 13 - 21 m, slowly increasing in last days before the impact, where the brightness is increasing very quick. Asteroids on
the last revolution before the collision, for a month before the impact, have a horizontal parallax of some dozens of arcseconds. Wide-angle cameras can
easy reveal such parallax. Observers who search for Near-Earth asteroids usually devote special attention to "quick asteroids", which leave long traces
at the frames. The real "attacked" asteroids at their last 10 days are "slow" objects.
On sky scanner-telescope efficiency (Poster)
by SHESTOPALOV Dmitry, Shemakha Astrophysical Observatory, Azerbaijan Academy of Science, (Azerbaijan)
Two regimes of work of scanner-telescope intended for detection of the moving objects near Earth are considered. In the first regime, that one may
call "stopped", sky survey is realized due to diurnal rotation of the sky sphere. In the second regime ( "step by step") telescope exposes one and the
same sky area several times, and each exposition differs from other by a very small displacement along coordinate "declination". Then telescope turns on
angle equivalent to own field angle along the coordinate "right ascension" and again several "quasimotionless" exposures of next sky area are carried out and
so on. The formula describing efficiency of telescope-scanner work in these regimes was obtained. It is shown that other things being equal efficiency of
the second regime is approximately in 6 times as much as the first.
Physical investigations of asteroids in Shemakha Astrophysical Observatory (Poster)
by SHESTOPALOV Dmitry, Shemakha Astrophysical Observatory, Azerbaijan Academy of Science, (Azerbaijan)
Shemakha Astrophysical Observatory (ShAO AS of Azerbaijan) is situated 140 km from Baku city on the south foothills of the Great Caucasus Range, and is
1500 m above sea level. 2-m Zeiss reflector is the main observatory telescope which is in particular used for astrophysical observations of asteroids.
Physical studies of asteroids are the traditional direction of the observatory work. For the first time, the slight absorption band of pyroxene
at 550 nm was found in Vesta spectrum in 1980 [1]. After that it was registrated in 3 Juno spectrum [2] and other S-asteroid spectra [3]. This absorption band was rediscovered in spectra of Vesta and near Earth asteroids
[4]. Comparative investigations of properties of 505 nm band in asteroid, terrestrial pyroxene and meteorite spectra led to the following conclusion.
Variations of S-asteroid spectra are connected with variations of chemical composition of pyroxene which, as we assume, is on S-asteroid surfaces in the
greater quantity than in achondrites and ordinary chondrites [5]. The discovery of another slight absorption bands in the optical range of S-asteroid spectra, which may be assigned to Fe3+ cation (or Cr3+ cation) in
pyroxene, led to a thought that asteroid minerals could be formed in the oxidative conditions [6]. Now this possibility is debated in connection with
the discovery of aqueous alteration products in ordinary chondrite meteorites and OH absorption band in the spectrum of S-asteroid Hebe near 3000 nm [7].
Spectral properties of meteorites from the collection of Institute of Mines (St.-Petersburg, Russia) were also investigated and spectral classification of
achondrites and ordinary chondrites has been devised [8]. The comparison of spectral characteristics of achondrites and ordinary chondrites on the one
hand and main belt S-asteroids on the other hand showed their statistical significant differences. From here the conclusion was done on systematically different material compositions of these types of asteroids and meteorites
[9]. The same result was also obtained for near Earth asteroid 433 Eros [10], what is now confirmed by data obtained with the help of spacecraft NEAR [11]. The comparison of reflectance spectra of C-asteroids and carbonaceous
chondrites allowed to come to the following conclusion: the most ancient material of the Solar System presented by carbonaceous chondrites of CI group is practically absent on C-asteroid surface. Apparently, CI-material has been
mainly removed with C-asteroid surfaces or reworked in the process of the formation of the present-day regolith covers on asteroids [12].
In order to investigate asteroid material composition the method of
calculation of reflectance spectra of polymineral powder-like surface has been devised. Reflectance spectra of S-asteroids from various optical subtypes are simulated by this method. This permits approximately to determine the mineral
surface composition that, as we obtained, one may attribute to basaltic type [13]. Besides, probable reflectance spectra of main rock-forming minerals on
S-asteroid surfaces have been calculated [14]. Using the spectra it is possible approximately to determine the structural type and chemical composition of these minerals by remote sensed methods [15].
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15. D.I.Shestopalov, L.F.Golubeva //Astron. Vest.2001 (submitted).
On the possibility of the determination of asteroid rotation period from its astrometric position (Oral)
by SHEVCHENKO Vasilij, Astronomical Observatory of Kharkiv National University, Kharkiv (Ukraine)
A rise in accuracy of determination of asteroid astrometric positions leads to necessity to take into account a displacement of asteroid photocentre
(Hestroffer 1998; Batrakov et al. 1999; Owen et al. 1999). As it has been shown (Tungalag et al. 2000) the photocentre displacement depends essentially
on the asteroid shape, phase angle and surface light scattering and may reach a value equal to 0.4 asteroid angular radius. The displacement is different
for maximal and minimal asteroid projection. As a result of asteroid rotation the measured astrometric positions will be modulated with changes of the
photocentre displacement. These oscillations increase with increasing ofasteroid oblongness and of phase angle. It can give a possibility to
determine the asteroid rotation period and to estimate the asteroid pole orientation. Using the numerical modeling, the photocentre displacement
oscillations have been calculated to understand their really influence on asteroid astrometric positions. The practical recommendations on the
determination of the asteroid rotation period from the photocentre displacement are given.
Batrakov Yu.V., Chernetenko Yu.A., Gorel G.K., Gudkova L.A. 1999. A. & A., 352, 703-711
Hestroffer D. 1998. A. & A. 336, 776-781.
Owen
Jr. W.M., Synnott S.P., Null G.W. 1999. In Modern astrometry and astrodynamics. R. Dvorak, H.F. Haupt, K. Wodnor (Eds.), 89-101.
Tungulag
N., Shevchenko V.G., Lupishko D.F. 2000. Kinem. Fiz. Neb. Tel. V. 16, No. 6, 519-525.
Finding of smal bodies by there luminescent properties (Oral)
by SIMONIA Irakli, SIMONIA Tsitsino, Abastumani Observatory (Republic of Georgia)
Many carbonaceous minerals, silicates, oxides has the luminescent properties. The luminescence of this solid matter cause under influence from
UV radiation and electron, ion, fluxes. To number of interesting phenomenon belong catodo and ionoluminescence of minerals. Small bodies of the Solar
system, asteroids, comets may shows intensive and short luminescence under influence of the solar wind and in plasma's clouds which spread in the
interplanetary medium after solarflares.Bright and timly short ionoluminescence of the celestial bodies is natural tool for there finding and
study. Ionoluminescent properties may has also unknown planetary bodies on long distance from the sun. We are consider in this paper new method for
finding and study of small bodies by there luminescent properties. Spectral features and time of luminescence are considered as well. We are suggest also
experiments with objective prisms. Other sides of this problem are under discussion.
Asteroid satellites formation as a natural outcome of collisions (Oral)
by TANGA, P.(1),, MICHEL, P.(1),, BENZ, W.(2),, RICHARDSON, D(2)
(1)
Laboratoire Cassini, Observatoire de la Côte d´Azur, Nice (France)
(2) University of Bern (Switzerland)
(3) Dept. of Astronomy, university of Maryland(USA)
Numerical simulations ot the collisional fragmentation of asteroids have been performed by an SPH code. The gravitational evolution of fragments
has been simulated by an N-body code. Results clearly show the possibility to form satellites and binary bodies such ads those observed in recent years by
high resolution techniques.
Observational programs for asteroidal mass determination (Poster)
by THUILLOT, W. (1), BEC-BORSENBERGER(1), A., RAPAPORT(2), ARLOT, J.-E.(1), M., BANGE,
J.F.(1)
(1)Institut de mécanique céleste (IMCCE/Paris obs.) (France)
(2)Observatoire de Bordeaux (France)
The determination of the asteroidal masses is one of the difficult problems to solve in order to have a better knowledge of the asteroids, their origin
and their evolution. Among several methods, the observation of close encounters between asteroids has been successfully applied for this purpose.
We will give informations upon some previous results obtained and upon our observational programs performed both at the automatic meridian circles of the
Bordeaux Observatory and at the Haute-Provence Observatory in France.
Astrometry applied to search for satellites of asteroids (Oral)
by THUILLOT, W., Institut de mécanique céleste (IMCCE/ Paris obs.) (France)
Thanks to the adaptive optics and the radar observations, asteroidal satellites appear to be much more common than believed in the last decennies.
Observational programs may be led with large telescopes equipped with efficient devices in order to detect these objects, but the targets need to be
well defined and some lists of asteroids candidates have to be preliminary established. We propose to perform this kind of research using astrometric
measurements with small telescopes using the ability to lead there coordinated programs spanning several revolution periods of the probable satellites. We
will describe a method which can be applied in order to detect an astrometric signature of the probable satellites.
The recovery as an important part of NEA astrometric follow-up (Poster)
by TICHA J., TICHY M. and KOCER M., Klet Observatory, Ceske Budejovice (Czech Republic)
The number of known Near-Earth Asteroids (NEAs) has rapidly increased in recent years due to LINEAR and other large surveys (Spacewatch, LONEOS, NEAT
and CSS). This discovery process has to be folloved by follow-up observations to obtain a sufficient number of precise astrometric data needed for an
accurate orbit determination of newly discovered bodies. About forty per cent of the known NEOs have been observed for more than one opposition.
This follow-up process starts by confirmatory observations and continues over a sufficient observing arc in the discovery apparition. Accurate orbit
determination requires observations from at least two oppositions. If asteroids are not found in the next apparition, different from the discovery
one, then they can be considered lost. This is particularly embarrassing for NEAs. Therefore NEA recovery is a very important part of NEA follow-up
astrometry. If data for different apparitions are not find in the course of precovery surveys or in other achive data, then it is necessary to prepare
targeted observations of a particular NEA in the second convenient apparition.
We discuss here methods, techniques and results of planned recoveries at
the Klet Observatory using 0.57-meter telescope equipped with a CCD detector.
We also mention the overall work on NEA recoveries provided by several NEO
follow-up programmes as well as a need for communication resources supporting astrometric observers.
Finnaly we present here a planned extension of Klet NEA recovery
subprogramme to fainter objects by means of larger 1-m telescope, which is being built at Klet now.
Asteroid 16 Psyche: VR polarimetry and photometry (Oral)
by VELICHKO Fiodor, Astronomical observatory Kharkiv (Ukraine)
(not received)
How the observations of Mimas allow to determinate the eccentricity of Tethys,and then to understand the origin of the Mimas-Tethys
commensurability (Oral)
by VIENNE A., Institut de mécanique céleste and Laboratoire d´Astronomie, IMCCE Paris Observatory (France)
Some recent studies have shown that the eccentricity of Tethys has a deciding action upon the evolution, under tidal effects, of the resonance
Mimas-Tethys. The reason is that Tethys' eccentricity induces secondary resonances in which the system can be temporarily captured. For example, the
probability of capture in the main resonance may have been much greater than the previous admitted value 0.04 (up to 1). In past studies, the orbit of
Tethys was always supposed to be circular: probably because, this eccentricity is not measurable on the orbit of Tethys itself. Its value is badly known. In
fact, when we look at the new dynamical model TASS, we find that the ellipticity of the orbit of Tethys is more influent on the position of Mimas.
In the present work, we present a new determination of this eccentricity. We use an analysis of the mean longitude of Mimas in which the eccentricity of
Tethys has a notable influence. The recent reduction of precise CCD observations of Mimas allows to make such analysis.
The use of radar and optical observations of Near-Earth Asteroids and main belt minor planet for different astronomical purposes (Oral)
by YAGUDINA Eleonora I., Institute of Applied Astronomy Russian Academy of Sciences (IAA RAS), St. Petersburg (Russia)
NEA-Earth Asteroids (NEAs) are the solar system special class objects attracting the attention of astronomical community especially during several
last decades: due to close and regular approaches to the Earth the radar observations of NEAs can be obtained for greater number of objects than those
of the main belt minor planets. The problem of usage of all available radar observations together with optical ones in combined solution is discussed for
different astromet- rical problems such as asteroid orbits, catalog orientation parameters , asteroid masses determination. About 20000 radar and
optical observations of twenty NEAs and four main belt minor planets have been used for the purposes.
Research of binary asteroid 1996 FG3 (Oral)
by ZHELEZNOV Nikolaj, Laboratory of Small Bodies of the Solar System, Institute of Applied Astronomy, Russian Academy of Sciences (IAA RAS), St.
Petersburg (Russia)
With the aim to determine orbital and physical characteristics of binary asteroid 1996 FG3 an attempt was made to approximate the components of the
system by homogeneous triaxial ellipsoids moving under the influence of the Sun and mutual gravitation. The force function of gravitational interaction of
components was presented in the form of power series of spherical functions up to 4th harmonic. The equations of prograde-rotational motion were integrated
by Everhart's method. Computed values of coordinates of components and Euler's angles of their orientation in space were used for simulation of lightcurves
of binary system. Basing on the method of approximation of ellipsoid surface by great number of small plane facets the program of lightcurve simulation
taking into account the mutual shadowings and occultations of components has been developed. The above programs have been used for approximation of
lightcurves of the system obtained by Pravec et al. (Icarus, V.146, N 2, 2000). Assuming coincidence of orbital plane of the satellite with equatorial
plane of the primary acceptable agreement between the real lightcurves and model ones has been achieved. Satellite orbit, density and mean diameters of
components have been determined. Parameters of ellipsoids representing primary and satellite have been found too. The research of prograde-rotational motion
of the system allows one to reveal some peculiarities of component motion and to draw some conclusions about its stability.
Last revised October 5, 2001