[IAUC] IAUC 9267: S/2012 (2577) 1 [25139-2012/04-R1]

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                                                  Circular No. 9267
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU en EPS.HARVARD.EDU           ISSN 0081-0304
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S/2012 (2577) 1
     W. J. Merline, Southwest Research Institute (together with P.
M. Tamblyn, B. D. Warner, P. Pravec, J. P. Tamblyn, C. Neyman, A.
R. Conrad, W. M. Owen, B. Carry, J. D. Drummond, C. R. Chapman, B.
L. Enke, W. M. Grundy, C. Veillet, S. B. Porter, C. Arcidiacono, J.
C. Christou, D. D. Durda, A. W. Harris, H. A. Weaver, C. Dumas, D.
Terrell, and P. Maley) reports the discovery, using the Keck II
telescope (+ NIRC2 Laser-Guide-Star adaptive-optics system), of a
second satellite of the Hungaria-type minor planet (2577) Litva.
On 2012 June 22.3 UT, the satellite was found at p.a. 89 deg and
separation 0".229 (projected separation 230 km).  At that time,
(2577) was 1.39 AU from the earth at magnitude V = 16.6.  The
satellite has been imaged in the K_p, H, and J bands.  It was also
detected on 2012 June 27, Aug. 11, and Aug. 16.  Failure to detect
it on 2012 July 15 is now seen to be due to being in conjunction
with the primary.  Follow-up observations were made at the Keck II
telescope on 2013 Aug. 25 and 26 by Merline, Tamblyn, Conrad, and
Tamblyn.  Additional detections were made at the Large Binocular
Telescope by Veillet and Arcidiacono on Oct. 12 and at the Keck II
telescope by Grundy and Porter on Oct. 25, giving a total baseline
of 490 days.  The best-fit orbit analysis indicates that the third
component has a semi-major axis of 378 km and an orbital period of
214 days; a period of half this length cannot be ruled out.  Either
orbit would be among the longest periods known for main-belt
multiple systems and would be the most loosely bound.  It resembles
other wide binary systems discovered by this same group (cf. Durda
et al. 2010, Proc. Lunar and Planet. Sci. Conf. 41, 2558; Jacobson
et al., Ap.J., submitted).  The third component is about 2.6 mag
fainter than the combined brightness of the close inner pair.
Using H magnitudes to scale the size of (2577) from other E-type
objects of better-known size, the diameter of (2577) is estimated
to be about 4 km, implying a size for the new satellite of 1.2 km.
The first satellite of (2577) was inferred by Warner et al. (CBET
1715) in 2009 via lightcurve analysis; their estimate of the size
ratio was 0.35, meaning that the second component would be 1.4 km
diameter, based on the 4-km assumption for (2577), above.  This
close inner pair is unresolvable in the imaging data reported
above.  Warner et al. (2009, Minor Planet Bull. 36, 165) suggested
that a residual 5.7-hr lightcurve period may be due to rotation by
a third body -- an idea bolstered by Pravec et al. (2012, Icarus
218, 125), who found that this period was still evident even when
the secondary object was in eclipse.  To the authors' knowledge,
S/2012 (2577) 1 is the only satellite to have been predicted prior
to being found by targeted imaging.  Additional information is
provided on CBET 3765.

                      (C) Copyright 2013 CBAT
2013 December 22               (9267)            Daniel W. E. Green