Electronic Telegram No. 5192
Central Bureau for Astronomical Telegrams
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(19281) 1996 AP_3
     V. Benishek, Belgrade Astronomical Observatory; P. Pravec, P. Fatka, K.
Hornoch, and P. Kusnirak, Ondrejov Observatory; P. Bacci and M. Maestripieri,
Astronomical Observatory, San Marcello Pistoiese, Italy; A. Marchini and R.
Papini, Dipartimento di Scienze Fisiche, Della Terra e Dell'Ambiente,
University of Siena; and D. Pray, Sugarloaf Mountain Observatory, South
Deerfield, MA, U.S.A., report that photometric observations taken with a
0.35-m telescope at the Sopot Observatory in Serbia, a 0.65-m telescope at
Ondrejov Observatory, a 0.60-m telescope at the San Marcello Pistoiese
Observatory, a 0.30-m telescope at the Astronomical Observatory of the
University of Siena, and a 0.50-m telescope at the Sugarloaf Mountain
Observatory during June 30-Aug. 4 reveal that minor planet (19281) is a
binary system with an orbital period of 22.27 +/- 0.01 hr.  The primary shows
a period of 2.37256 +/- 0.00010 hr and has a lightcurve amplitude of 0.17 mag
at solar phases 5-20 degrees, suggesting a nearly spheroidal shape.  Mutual
eclipse/occultation events that are 0.07 magnitude deep indicate a lower
limit on the secondary-to-primary mean-diameter ratio of 0.26.  The secondary
appears synchronous and has a light-curve amplitude (in the combined primary-
plus-secondary light curve) of 0.02 mag, suggesting a moderately elongated
shape with an equatorial-axis ratio of 1.3 +/- 0.1.  The mean absolute
magnitude in the Cousins R photometric system is H_R = 13.41 +/- 0.08,
assuming the phase-relation slope parameter G = 0.24 +/- 0.11.


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2022 November 20                 (CBET 5192)              Daniel W. E. Green