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MASTER detection of Near-Earth Object 9 hours before the very close fly-by

ATel #5432; P. Balanutsa, M. Pruzhinskaya, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Yecheistov, V. Vladimirov (Moscow State University, SAI), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova (Irkutsk State University), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov, A. Gabovich (Blagoveshchensk Educational University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of Pulkovo Observatory), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), P. Podvorotny, V. Shumkov, S. Shurpakov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 29 Sep 2013; 10:48 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Optical, Asteroid, Near-Earth Object

During the observations of flaring blazar 3C 454.3 in two polarization filters, MASTER-Tunka robotic telescope (double 0.40-m f2.5 reflector + 4kx4k CCD, filed of view 2.1x2.1 deg) has serendipitously detected the Fast Moving Object of 16m visible in both tubes. The object was located near the edge of FOV, about 1 deg south of 3C 454.3. First it was detected on the set of ten 30-sec exposures from 13:20 to 13:37 UT with limiting magnitudes 17.3-17.5. Another set of ten 60-sec exposures was then obtained from 13:44 to 14:05 UT with the limits 18.1-18.2 in both tubes.

The animation of ten 60-sec exposures from the Eastern tube is uploaded to http://master.sai.msu.ru/static/NEO/MASTER-NEO-130927-Tunka-anim.gif

The object was moving at the rate of 6.2" per minute in positional angle 71. Astrometry from 8 images was reported to Minor Planet Center using the designation MASD91. Using Find_Orb orbit determination software by Bill Gray (www.projectpluto.com) we have obtained the following orbital elements:

Epoch 2013 Sep 28.0 TT = JDT 2456563.5   Earth MOID: 0.0000   Ve: 0.0772 
M 343.67888              (2000.0)        Ma: 0.0016 
n   0.36126837     Peri.  252.01974      0.22930384     -0.97326783 
a   1.95246273     Node   184.78142      0.94166328      0.22520304 
e   0.6228503      Incl.    8.98491      0.24635343      0.04509218 
P   2.73/996.47d   H   27.7     G   0.15   q 0.73637071  Q 3.16855475 
From 8 observations 2013 Sept. 27 (44.4 min); mean residual 0".295. 
Absolute magnitude H=27.7 corresponds to the body of approximately 15 meters in size, similar to that of Chelyabinsk meteorite. According to Find_Orb, the object has passed about 11300 km above the Earth surface at 22:50 UT on 2013 Sep. 27 over the Indian ocean, approximately at 90E, 0N. The geocentric distance at the closest approach was thus about 17700 km, or 0.00012 AU. That puts the object at Top 5 closest approaches to the Earth by minor planets listed at http://www.minorplanetcenter.net/iau/lists/Closest.html

At the beginning of MASTER-Tunka observations (13:20 UT, 9.5 hours before the closest approach) the object's topocentric distance was 556433 km (1.45 Moon distances), reducing to 512345 km by 14:05 UT. The approach velocity during MASTER-Tunka observations was 16.5 km/s. The object could not have been discovered before Sep. 25 when its calculated magnitude was fainter than 21m. Currently it is moving towards the Sun and can not be observed anymore.

We have checked the NORAD database, JPL Horizons website and DASO page and found no matches among the artificial objects. However, taking into account very small orbital intersection distance with Mars, the man-made origin of the object can not be excluded.

Global MASTER Robotic Net