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MASDB2 identified with the man-made object

ATel #5616; D. Denisenko, V. Lipunov (Moscow State University, Sternberg Astronomical Institute)
on 1 Dec 2013; 12:14 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Optical, A Comment, Asteroid, Near-Earth Object

MASDB2 = TA29DCF

A slowly moving 16-mag object MASDB2 detected by MASTER-Amur robotic telescope was reported in ATel #5610. Between 17:45 and 18:46 UT on 2013 Nov. 28 the object was moving at approximately 12" per hour (2-3 times slower than the Main Belt asteroids and ~150 times slower than the Moon). However, it was not found in MASTER-Kislovodsk follow up images (field of view 2x2 deg.) obtained on 21:50 and 22:20 UT.

Following the private communication by K. Sokolovsky, we have checked the Minor Planet Center's Distant Artificial Satellites Observation Page. Ephemerides of eleven objects were obtained for 2013 Nov. 28 using [D54] observatory code of MASTER-Amur (the remaining eleven were Outside range of available ephemeris data). One of those objects with available ephemeris named TA29DCF matched the observations of MASDB2 within 15' accuracy in position, 1.5m in brightness and, what is mostly important, in the slow motion (about 0.2" per minute, or 0.2' per hour). Here is the excerpt of the ephemeris provided by DASO Page (date, azimuth and elevation omitted):

TA29DCF 
 
UT      R.A. (J2000) Decl.  Elong.  V        Motion      Distance 
 h m                                      "/min   P.A.       km 
----------------------------------------------------------------- 
1400   07 47 34.7 -07 01 50 121.2  17.6    8.07  097.2     297293 
1500   07 48 01.3 -07 02 48 121.2  17.6    5.28  099.6     294306 
1600   07 48 17.2 -07 03 34 121.1  17.5    2.86  103.0     291411 
1700   07 48 24.5 -07 04 03 121.2  17.5    0.99  109.2     288662 
1800   07 48 25.7 -07 04 12 121.2  17.5    0.18  285.2     286099 
1900   07 48 24.2 -07 03 57 121.2  17.5    0.64  315.4     283746 
2000   07 48 23.3 -07 03 17 121.3  17.5    0.88  010.9     281607 
2100   07 48 26.7 -07 02 13 121.3  17.4    2.08  052.9     279667 
2200   07 48 37.7 -07 00 48 121.3  17.4    4.24  068.1     277896 
-----------------------------------------------------------------
We note that the chance coincidence in the orbital geometry and the position of observatory have provided an exceptionally slow motion of this man-made object during the observations by MASTER-Amur. Taking into account the object's distance (approximately 3/4 that of the Moon, or 45 Earth radii) explains why it was not found by MASTER-Kislovodsk 3 hours later.

A little investigation in Google has shown that TA29DCF is actually an upper stage of RadioAstron (Spektr-R) telescope developed by the Astro Space Center of the Lebedev Physical Institute and launched into high-apogee orbit on 2011 July 18. The latest orbit computation by Bill Gray on 2013 Nov. 19 gives the following parameters: a=175314 km, e=0.9428776, i=6.55675, q=10014 km, Q=340614 km, P=8.46d, H=27.9. Additional information can be found in Minor Planet Mailing List message [MPML 29194] and in DASO Circulars.

We thank Kirill Sokolovsky (ASC Lebedev/SAI MSU) for his useful advice. We apologize for any troubles caused by our original announcement in ATel and at the NEO Confirmation Page.

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