Electronic Telegram No. 4902
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


(4788) SIMPSON
     P. Sogorb, La Bastide des Jourdans, France; P. Pravec, Ondrejov
Observatory; M. Husarik, G. Cervak, and M. Pikler, Skalnate Pleso Observatory;
R. Durkee, Shed of Science South Observatory, Pontotoc, TX, U.S.A.; V.
Benishek, Belgrade Astronomical Observatory; J. M. Bosch, Santa Maria de
Montmagastrell, Tarrega, Spain; R. Behrend, Geneva Observatory; and V.
Chiorny, Kharkiv Observatory, report that photometric observations taken with
a 0.28-m telescope at the Bastidan Observatory in France, a 0.61-m telescope
at the Skalnate Pleso Observatory, a 0.50-m telescope at the Shed of Science
South Observatory, a 0.35-m telescope at the Sopot Observatory in Serbia, a
0.41-m telescope at the Santa Maria de Montmagastrell Observatory, and a
0.70-m telescope at the Chuguev station of the Kharkiv Observatory in Ukraine
during 2020 Sept. 27-Nov. 15 reveal that minor planet (4788) is a binary
system with an orbital period of 14.98 +/- 0.01 hr.  The primary shows a
period of 2.81752 +/- 0.00008 hr and has a light-curve amplitude of 0.18 mag
at solar phases 4-12 degrees, suggesting a nearly spheroidal shape.  Mutual
eclipse/occultation events that are 0.03 to 0.07 magnitude deep indicate a
lower limit on the secondary-to-primary mean-diameter ratio of 0.17.  There
is also a second rotational lightcurve component with a period of 3.1506 +/-
0.0002 hr and an amplitude of 0.03 mag in the combined primary-plus-secondary
lightcurve, which may belong to the eclipsing/occulting secondary or to a
third body of the system.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2021 CBAT
2021 January 7                   (CBET 4902)              Daniel W. E. Green