Electronic Telegram No. 5244
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
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Prepared using the Tamkin Foundation Computer Network


(1990) PILCHER
     V. Benishek, Belgrade Astronomical Observatory; P. Pravec, Ondrejov
Observatory; F. Pilcher, Organ Mesa Observatory, Las Cruces, NM, U.S.A.; M.
Husarik, A. Voitko, D. Tomko, M. Pikler, and G. Cervak, Skalnate Pleso
Observatory; and A. Marchini and R. Papini, Dipartimento di Scienze Fisiche,
Della Terra e Dell'Ambiente, University of Siena, report that photometric
observations taken with a 0.35-m telescope at the Sopot Observatory in Serbia,
a 0.35-m telescope at the Organ Mesa Observatory, 0.61-m and 1.3-m telescopes
at the Skalnate Pleso Observatory, and a 0.30-m telescope at the Astronomical
Observatory of the University of Siena during 2022 Dec. 29-2023 Feb. 20
reveal that minor planet (1990) is a binary system with an orbital period of
17.146 +/- 0.002 hr.  The primary shows a period of 2.84096 +/- 0.00007 hr
and has a lightcurve amplitude of 0.11 mag at solar phases 3-9 degrees,
suggesting a nearly spheroidal shape.  Mutual eclipse/occultation events that
are 0.05 magnitude deep indicate a lower limit on the secondary-to-primary
mean-diameter ratio of 0.22.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2023 CBAT
2023 April 22                    (CBET 5244)              Daniel W. E. Green