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Russian Academy of Sciences
Central Astronomical Observatory at Pulkovo


August 22-26, 2005

Edited by P. Kenneth Seidelmann and Victor K. Abalakin

St. Petersburg, 2005


Peter Sukhov

Observations of the GEO were resumed at the Odessa Astronomical Observatory (OAO) in 2002, and for these observations the telescope, which is located at the observation station of Mayaki, was used. The coordinates of the telescope are as follows:

- Latitude 46.4 N, longitude 30.3 E;
- the height above sea level 24 m;
- the visible arc of the GEO ring is 130.

Currently there are two operating telescopes:
  1. The 0.6 m Ritchey-Chretien telescope has a 1 FOV. It is equipped with the FLI CCD of 1024 px x 1024 px, 24 mm, and reaches 16m.5 in 5 sec. integration time. With the Superizokon LI-804 TV-tube, the detection threshold is ~15m.5 per 0.08 sec. integration time.
  2. The 0.5 m Cassegrain telescope is equipped with B, V, R filters and the FEU-79 photoelectronic multiplier with the detection threshold of ~13m.5. The accuracy of magnitude measurements is 0m.02. All telescopes are produced by the optical and mechanical workshops of the OAO.

Site, institution, countryNumber of clear nights per yearCoordinates, GEO RingTelescopeEquipmentFOVLimiting visible magnitude for an AE satelliteStatus
Mayaki, Odessa Astronom. Observat. Ukraine1808030.3 E 46.4 N 24 m GEO Ring 35 W95 E60-cm, 1: 6, Ritchey-Chretien.CCD, FLI 1024x1024 24mm,116m.5 for 5 sec integr. timeActive
or superizoon TV tube LI-80415m.5 for 0.08 sec. integr. timeActive
10 cm, 1:2 50-cm CassegrainIzoon LI- 801208m.5 for 0.04 sec integr. timeActive
FEU-79 photometer B, V, R 13m.5Active

The astronomers get from observations the monochrome raster file in gradations of the gray. In television such a file is the "signal file". We propose to convert the signal file into a model file and to extract the coordinate and photometrical information at the "model file rate. It is possible to describe the image of the starry sky mathematically as the two- dimensional pulsed parametric field in which every object is described in terms of the set of the following numerical characteristics:

- (X0, Y0) are the coordinates of the optical radiation entroid;
- S, the area occupied by the image of an object;
- B(S), the total energy B (the brightness) from the area S;
- N, the number of objects in a frame.

The volume of the signal file is of a few Mbytes, but the model file volume is of 2-3 Kbytes. So, the operative efficiency by the automated processing is increased. Also the probability of a successful identification of an object increases by theprocessing. A fragment of a model file is shown below:

Satellite. 1: x = 360, y = 254, brightness: 1560
Satellite. 2: x = 340, y = 278 brightness: 560
Star No. 1: x = 373, y = 516, brightness: 2496
Star No. 2: x = 536, y = 430, brightness: 2340
Star No. 3: x = 589, y = 306, brightness: 5460
Star No. 4: x = 703, y = 18, brightness: 14196
Star No. 5: x = 65, y = 390, brightness: 2028

The photometry of the GEO objects allows to classify the objects using astrophysics methods, also the character of the center of mass motion gives important information related to the status of an object, and, accordingly, about dangerous approaches to the actively functioning ones.

The photometrical observations in the optical range carried out simultaneously with the VLBR radar observations are of a great interest. We have participated in these observations since 2003. A sample of the photometric light curve for the GEO object 71235 is given and compared to the radar curve.

Fig. 1. The fragment of the photometric light curve in the integral radiation is obtained on 21.06.2004 for the GEO object 71235. The signal accumulation time is 1 sec. The period has been determined by use of the Spectr software package, being applied usually for a study of quickly changing processes, and the Breger program package. Two periods 1=32.22 sec and 2=16.11 sec have been found.

Fig. 2. The curve the signal intensity vs. time showing the power change of the reflected radio signal in the VLBR experiment obtained by use of the Evpatoria RT-70 => Bear Lakes RT-64 bi-static system on 03.10.20004 for the GEO object 71235. The time of the sampling radio signal is 0.016 sec. The power change period is P = 31.85 sec.

The small difference in the period is possibly due to the fact that the light curves represent the integrated signals from the entire surface whereas the radar ones represent the radiation coming out from separate details of the object. The same reasoning might explain the different accumulation times.

Both astrometrical and photometrical observations of the GEO objects are carried out in accordance with the ephemerides received from Pulkovo Observatory and KIAM. The work of the Mayaki observation station of OAO, in the framework of the Pulkovo optical observers cooperation program, will be continued in the future. We should like to invite other interested organizations to this cooperation.

  1. C .., . ǻ. 2003, , 2, , .., , 2003 . c.193-198. (Sukhov P.P., Strigin N.Z., et al. On the intraframe processing of images of the starry sky areas by the television AES observations., Proceedings of the Conference Near-Earth Astronomy-2003, Institute for Astronomy of the Russian Academy of Sciences. St. Petersburg, 2003, p.193198 (in Russian).
  2. Classification of Geosynchronous objects. ESOC, Issue 6, 2004.

20 2006.

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