Electronic Telegram No. 5665
Central Bureau for Astronomical Telegrams
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(32230) 2000 OP_27
     Ye Yuan, Purple Mountain Observatory (PMO), reports the discovery of an
apparent satellite for the main-belt minor planet (32230), based on a stellar
occultation of the Tycho-catalogue star 4733-01769-1 (Gaia magnitudes G =
9.96, RP = 9.31) as observed on 2024 Nov. 22.56 UT.  The event was recorded by
Yang Zhang and Yuchen Lin at the same observing site near Hanjiang, Putian,
Fujian, China.  The predicted shadow velocity was 11.3 km/s.  Given the
magnitude difference (star approximately 7.0 mag brighter than the minor
planet at mag V about 17.0), the occultations resulted in essentially complete
extinction of the stellar flux.  Observations were obtained using two
independent telescopes separated by a few meters in distance, both equipped
with GPS-disciplined QHY174M cameras.  Zhang used a 0.28-m RASA telescope
(EQ8 mount), while Lin used a Celestron 0.23-m f/6.3 telescope (AM5 mount).
Both systems recorded two distinct extinction events with consistent timing
and morphology.  The first occultation component lasted 0.198 +/- 0.008 s
(Zhang) and 0.194 +/- 0.027 s (Lin), corresponding to chords of 2.24 +/- 0.09
and 2.19 +/- 0.31 km, respectively.  The second occultation component lasted
0.716 +/- 0.014 s (Zhang) and 0.727 +/- 0.028 s (Lin), corresponding to chords
of 8.09 +/- 0.16 and 8.22 +/- 0.32 km, respectively.  The intervals between
the mid-times of the two components were 4.370 +/- 0.017 s (Zhang) and 4.367
+/- 0.039 s (Lin), implying projected separations of 49.38 +/- 0.19 and 49.35
+/- 0.44 km, respectively, along the shadow path.  A binary star explanation
is ruled out because both components produced full extinction events.  The
NEOWISE-derived diameter of (32230) is 12.0 +/- 0.2 km.  Follow-up photometric
observations led by the PMO team (using the 0.8-m YAHPT telescope during 2024
Nov. 22-Dec. 6 and the DC-RASA11 telescope during 2026 Jan. 13-Feb. 6) reveal
a maximum light-curve amplitude of about 0.30 mag, indicating the 1.3:1 ratio
of the major and minor axes for an ellipse model.  The large projected
separation (about 49 km) relative to the primary diameter (about 12 km),
combined with the low light-curve amplitude, effectively rules out a single
elongated or contact binary model.  The observations are best explained by
the existence of a minor-planet satellite.  This work was supported by the
occultation project led by Ye Yuan.  Technical analysis was supported by
Ansheng Zhu and Ke Wang (PMO), together with Chenyang Guo, Third Institute
of Oceanography, utilizing SharpCap, Tangra, SORA, and Tycho-Tracker software.


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                         (C) Copyright 2026 CBAT
2026 February 23                 (CBET 5665)              Daniel W. E. Green