[Iaude] CBET 4787: (264357) 2000 AZ_93

quai at eps.harvard.edu quai at eps.harvard.edu
Sat May 30 01:55:04 EDT 2020

                                                  Electronic Telegram No. 4787
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

(264357) 2000 AZ_93
     J. D. Giorgini and D. Farnocchia, Jet Propulsion Laboratory (JPL); D. C.
Hickson, S. E. Marshall, L. F. Zambrano-Marin, and A. K. Virkki, Arecibo
Observatory, University of Central Florida; and P. A. Taylor, Lunar and
Planetary Institute, Universities Space Research Association, report that a
non-gravitational acceleration has been detected influencing the motion of
the Aten-class minor planet (264357) 2000 AZ93 (designated as a "potentially
hazardous" object).  The initial echo Doppler-shift on 2019 Dec. 17 was found
7.1-sigma from the expectation of gravity-only dynamics.  The Arecibo S-band
(2380-MHz, 12.6-cm) Doppler-shift and four round-trip delay measurements
obtained on Dec. 17 have an offset of 2.65 +/- 0.1 Hz and 6.5-sigma mean
offsets of -2015.8 (+/- 2.3) x 10**-6 s, respectively, relative to ballistic
motion from the pre-experiment dataset (119 plane-of-sky optical angle pairs
spanning 2000-2011 in JPL orbit solution 32).  When combined with the current
optical dataset (144 angular pairs spanning 2000-2020) in JPL orbit solution
43, a heliocentric r**-2 transverse A_2 non-gravitational acceleration at 1
AU of -9.7 (+/- 1.2) x 10**-13 m/s**2 over the data arc was estimated,
reducing total post-fit residual chi-squared from 100 to 39.  Estimates of
radial (A_1) and normal (A_3) non-gravitational acceleration components did
not produce statistically significant detections.  The current dataset cannot
distinguish between outgassing dynamics (7.8-sigma detection) or the r**-2
acceleration dynamic given above (8.1-sigma detection).  The object was not
well-resolved in delay-Doppler imaging.  The echo bandwidth was 0.4 to 0.5 Hz.
The radar astrometry is available at URL https://ssd.jpl.nasa.gov/?radar.

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                         (C) Copyright 2020 CBAT
2020 May 30                      (CBET 4787)              Daniel W. E. Green

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