[IAUC] CBET 3765: 20131222 : S/2012 (2577) 1

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3765
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


S/2012 (2577) 1
     W. J. Merline, Southwest Research Institute (SwRI); P. M. Tamblyn, Binary
Astronomy, LLC, Dillon, CO, U.S.A., and SwRI; B. D. Warner, Center for Solar
System Studies, Landers, CA, USA; P. Pravec, Ondrejov Observatory; J. P.
Tamblyn, Binary Astronomy, LLC, Dillon, CO, U.S.A.; C. Neyman, W. M. Keck
Observatory; A. R. Conrad, Max Planck Institute for Astronomy; W. M. Owen, Jet
Propulsion Laboratory; B. Carry, Institut de Mecanique Celeste et de Calcul
des Ephemerides, Paris Observatory; J. D. Drummond, Starfire Optical Range,
Air Force Research Laboratory, Kirtland Air Force Base, Albuquerque, NM,
U.S.A.; C. R. Chapman and B. L. Enke, SwRI; W. M. Grundy, Lowell Observatory;
C. Veillet, Large Binocular Telescope Observatory (LBTO); S. B. Porter, Lowell
Observatory; C. Arcidiacono, Astronomical Observatory of Bologna, Istituto
Nazionale di Astrofisica; J. C. Christou, LBTO; D. D. Durda, SwRI; A. W.
Harris, "More Data!", La Canada, CA, USA; H. A. Weaver, Applied Physics
Laboratory, Johns Hopkins University; C. Dumas, European Southern Observatory,
Chile; D. Terrell, Sonoita Research Observatory and SwRI; and P. Maley,
Houston, TX, USA, report 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,
despite excellent conditions, is now seen, in retrospect, to be due to being
in conjunction with the primary.  Follow-up observations were made at the Keck
II telescope (+ LGS-AO) on 2013 Aug. 25 and 26 by Merline, Tamblyn, Conrad,
and Tamblyn.  Additional detections were made at the Large Binocular Telescope
(adaptive secondary mirror and PISCES near-infrared camera at the "Right Front
Bent" Gregorian focus) by Veillet and Arcidiacono on 2013 Oct. 12 and at the
Keck II telescope (+ LGS-AO) by Grundy and Porter on 2013 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.  Despite the
long baseline and the number of observational epochs, the phasing of the
observations is such that a period of half this length cannot be ruled out.
Either orbit would be among the longest periods known for main-belt binary/
multiple systems and would also 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, as viewable at website URL http://lanl.arxiv.org/abs/1311.4887).
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 discovered by Warner et al. (CBET 1715)
in 2009, by lightcurve analysis, revealing eclipses/occultations by a close
secondary, having an orbital period of 35.9 hr; 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 further 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.
     The observing program described here has given high priority to objects
suspected of having satellites.  To the authors' knowledge, S/2012 (2577) 1 is
the only satellite to have been predicted prior to being found by targeted
imaging.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 December 22                 (CBET 3765)              Daniel W. E. Green