[Iaude] CBET 4593: 20190108 : 2016 AZ_8

quai at eps.harvard.edu quai at eps.harvard.edu
Mon Jan 7 19:59:17 EST 2019

                                                  Electronic Telegram No. 4593
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

2016 AZ_8
     A. K. Virkki, S. E. Marshall, F. C. F. Venditti, and L. F. Zambrano
Marin, Arecibo Observatory, University of Central Florida; and E. G.
Rivera-Valentin and P. A. Taylor, Lunar and Planetary Institute, Universities
Space Research Association, report that Arecibo (2380-MHz, 12.6-cm) range-
Doppler radar images obtained on Jan. 4.72 UT reveal that the Apollo-type
minor planet 2016 AZ_8 is a binary system.  Preliminary measurements of
visible-range extents in radar images with 7.5-m/pixel resolution suggest a
rounded primary of diameter 420 +/- 60 m and an elongated secondary 180 +/-
30 m long.  This implies a visual albedo of 4 +/- 1 percent for an absolute
magnitude of 21.0.  The system was observed near maximum range separation
along the line-of-sight at 420 +/- 45 m, which is a lower bound on the
mutual-orbit scale due to possible projection effects.  Echo bandwidths
place upper bounds on the rotation periods of the primary and secondary
of 7 and 40 hours, also subject to projection effects.  Further observations
are encouraged; no more radar observations from Arecibo are possible this
apparition.  A projected separation comparable to the primary diameter and
the slow projected rotation periods suggest the mutual-orbit plane of the
system may have been inclined by tens of degrees relative to the line-of-sight
during the observations. As such, observers should assume typical parameters
for such binary systems of 2-4 hours for the primary rotation period and a
mutual-orbit period between 12 and 24 hours.

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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2019 CBAT
2019 January 8                   (CBET 4593)              Daniel W. E. Green

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