OBSERVATIONS OF HEO AT THE ODESSA ASTRONOMICAL
OBSERVATORY (UKRAINE)
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:
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.
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, country
Number of clear nights per year
Coordinates, GEO Ring
Telescope
Equipment
FOV
Limiting visible magnitude for an AE satellite
Status
Mayaki, Odessa Astronom. Observat. Ukraine
18080
30.3 E 46.4 N 24 m GEO Ring 35 W–95 E
60-cm, 1: 6, Ritchey-Chretien.
CCD, FLI 1024x1024 24mm,
1°
16m.5 for 5 sec integr. time
Active
or superizoсon TV tube LI-804
15m.5 for 0.08 sec. integr. time
Active
10 –cm, 1:2 50-cm Cassegrain
Izoсon LI- 801
20°
8m.5 for 0.04 sec integr. time
Active
FEU-79 photometer B, V, R
13m.5
Active
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 сentroid;
- 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 Р1=32.22 sec and Р2=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.
REFERENCES
Cухов П.П., и др. «О внутрикадровой обработке изображений участков звездного неба при
телевизионных наблюдениях ИСЗ». Околоземная астрономия – 2003, Сборник трудов конференции,
Том 2, Терскол, С.П., Институт астрономии РАН, 2003 г. 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.193–198 (in Russian).
Classification of Geosynchronous objects. ESOC, Issue 6, 2004.