Electronic Telegram No. 5219
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)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


(3959) IRWIN
     V. Benishek, Belgrade Astronomical Observatory; F. Salvaggio and
R. Papini, Wild Boar Remote Observatory, Florence, Italy; A. Marchini,
Dipartimento di Scienze Fisiche, Della Terra e Dell'Ambiente, University of
Siena; P. Pravec, Ondrejov Observatory; F. Pilcher, Organ Mesa Observatory,
Las Cruces, NM, U.S.A.; and R. Durkee, Shed of Science South Observatory,
Pontotoc, TX, U.S.A., report that photometric observations taken with a 0.35-m
telescope at the Sopot Observatory in Serbia, a 0.23-m telescope at the Wild
Boar Remote Observatory, a 0.30-m telescope at the Astronomical Observatory of
the University of Siena, a 0.35-m telescope at the Organ Mesa Observatory, and
a 0.50-m telescope at the Shed of Science South Observatory during 2022 Nov.
14-Dec. 24 reveal that minor planet (3959) is a binary system with an orbital
period of 15.641 +/- 0.004 hr.  The primary shows a period of 3.2591 +/-
0.0003 hr and has a lightcurve amplitude of 0.11 mag at solar phases 3-10
degrees, suggesting a nearly spheroidal shape.  Mutual eclipse/occultation
events that are 0.09 to 0.18 magnitude deep indicate a lower limit on the
secondary-to-primary mean-diameter ratio of 0.29.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2023 CBAT
2023 February 9                  (CBET 5219)              Daniel W. E. Green