[Iaude] CBET 4706: (5500) TWILLEY

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Dec 20 16:57:28 EST 2019

                                                  Electronic Telegram No. 4706
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

(5500) TWILLEY
     M. Conjat, Observatoire de la Cote d'Azur (using a 0.40-m telescope at
Nice Observatory); R. Montaigut, Club d'Astronomie de Lyon Ampere, France;
D. Augustin (using a 0.14-m refractor at "Deep Sky Chile", Pichasca, Chile,
and with C. Pinturaud using the IRiS-OCEVU 0.50-m telescope at Haute-Provence
Observatory); R. Behrend, Geneva Observatory, Switzerland; and P. Griveaud,
D. Mata, and J.-P. Rivet, Observatoire de la Cote d'Azur (using a 1.0-m
telescope at Calern Observatory, France) report that photometric observations
taken during Feb.-Mar. 2017 and during Nov.-Dec. 2019 reveal that minor planet
(5500) Twilley is a binary system with an orbital period of 17.556 +/- 0.008
hr.  The primary shows a period of 2.9554 +/- 0.0002 hr with a light-curve
amplitude of 0.15 magnitude at solar phases 18-3 degrees, suggesting a nearly
spheroidal shape.  Mutual eclipse/occultation events that are 0.08 to 0.13
magnitude deep indicate a lower limit on the secondary-to-primary mean-
diameter ratio of 0.27.

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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2019 CBAT
2019 December 20                 (CBET 4706)              Daniel W. E. Green

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