[IAUC] IAUC 9268: (8306); V1369 Cen = N Cen 2013 [25139-2012/04-R1]

Sab Dic 28 16:11:57 ART 2013

                                                  Circular No. 9268
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
New postal address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU en EPS.HARVARD.EDU           ISSN 0081-0304
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Prepared using the Tamkin Foundation Computer Network


(8306) SHOKO
     P. Pravec, P. Kusnirak, K. Hornoch, and A. Galad, Ondrejov
Observatory and European Southern Observatory, La Silla; Yu. N.
Krugly and V. Chiorny, Kharkiv Observatory; R. Inasaridze, O.
Kvaratskhelia, and V. Ayvazian, Abastumani Observatory; O.
Parmonov, Maidanak Observatory; J. Pollock, Appalachian State
University; S. Mottola, Calar Alto Observatory; J. Oey, Blue
Mountains Observatory, Leura, NSW; D. Pray, Sugarloaf Mountain
Observatory, South Deerfield, MA, U.S.A.; J. Zizka and J. Vrastil,
Charles University, Prague; I. Molotov, Keldish Institute of
Applied Mathematics, Moscow; and D. E. Reichart, K. M. Ivarsen,
J. B. Haislip, and A. LaCluyze, Physics and Astronomy Department,
University of North Carolina at Chapel Hill, report that
photometric observations obtained during 2013 Sept. 7-Dec. 7 reveal
that minor planet (8306) is a binary system with an orbital period
of 36.20 +/- 0.04 hr.  The primary shows a period of 3.3503 +/-
0.0002 hr, and it has a lightcurve amplitude of 0.11 mag at solar
phases 3-13 deg, suggesting a nearly spheroidal shape.  Mutual
eclipse/occultation events that are up to 0.26 mag deep indicate a
lower limit on the secondary-to-primary mean-diameter ratio of
0.40.  The secondary shows a period equal to the orbital period,
indicating synchronous rotation.  Residuals of the fit show an
additional brightness variation that may be due to rotation of a
third body of the system.  The mean absolute R magnitude of the
system is H_R = 14.83 +/- 0.07, assuming G = 0.24 +/- 0.11.  These
observations were run as a part of their photometric project
"NEOSource" within its task to study binary and multiple systems
among minor-planet pairs [i.e., pairs of minor planets that are in
highly similar heliocentric orbits (see Vokrouhlicky and Nesvorny
2008, A.J. 136, 280; Pravec et al. 2010, Nature 466, 1085)].  Minor
planet (8306) was selected as a target when found that it appears
paired with minor planet 2011 SR_158 using the method of Pravec and
Vokrouhlicky (2009, Icarus 204, 580), modified with use of the mean
elements from AstDyS-2 (see website URL
http://hamilton.dm.unipi.it/astdys2/) and with backward
integrations of their orbits using the method of Vokrouhlicky
(2009, Ap.J. 706, L37).  The integrations indicate that the pair
separated from a single body between 300 and 650 kyr ago.


V1369 CENTAURI = NOVA CENTAURI 2013
     Visual magnitude estimates:  Dec. 12.166 UT, 4.3 (R. Salvo,
Montevideo, Uruguay); 14.23, 3.6 (Salvo); 15.28, 3.5 (W. Souza, Sao
Paulo, Brazil); 16.281, 4.5 (Souza); 26.250, 4.1 (Souza); 28.302,
4.1 (Souza).

                      (C) Copyright 2013 CBAT
2013 December 28               (9268)            Daniel W. E. Green