Electronic Telegram No. 2705
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


(2815) SOMA
     J. Pollock, Appalachian State University; P. Pravec, P. Kusnirak, and K.
Hornoch, Ondrejov Observatory; V. Chiorny, Kharkiv Observatory; S. Gajdos,
Modra Observatory; 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 2011 Mar.
7 to Apr. 9 reveal that minor planet (2815) is a binary system with an
orbital period of 17.915 +/- 0.002 hr.  The primary shows a period of 2.73325
+/- 0.00007 hr and it has a lightcurve amplitude of 0.07 mag, suggesting a
nearly spheroidal shape.  Mutual eclipse/occultation events that are 0.12-
and 0.07-mag deep indicate a secondary-to-primary mean-diameter ratio of 0.25
+/- 0.02.  The mean absolute R magnitude of the system is H_R = 12.53 +/-
0.02 and the phase relation slope parameter G = 0.27 +/- 0.04.

      F. Marchis, J. E. Enriquez, and M. Allain, Carl Sagan Center at the SETI
Institute; and J. P. Emery, University of Tennessee at Knoxville, report on
integrated spectroscopic observations of the binary system (2815) recorded
from 2011 Apr. 1.4356 to 1.4832 UT with Infrared Telescope Facility's SPEX
instrument.  A solar analogue (SAO 119577) was observed before and after the
target to compute a final reflectance spectrum from 0.67 to 2.55 microns.
Following the Bus-DeMeo taxonomy, the near-infrared spectrum is typical of
Sq-type minor planets, characterized by a wide 1-micron absorption band with
evidence of an absorption feature near 1.3 microns.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2011 CBAT
2011 April 21                    (CBET 2705)              Daniel W. E. Green