Electronic Telegram No. 5382
Central Bureau for Astronomical Telegrams
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(5232) JORDAENS
     M. Simpson, B. Yeung, and G. Schmidt, Royal Astronomical Society of
Canada, Calgary, report the discovery of the binary nature of minor planet
(5232) from the occultation of the Tycho-catalogue star TYC 683-00635-1 on
2024 Feb. 1.064 UT.  The minor planet was 7.9 magnitudes fainter than the
10th-magnitude star.  Simpson and Yeung recorded GPS-timestamped video of the
occultation, with the light levels dropping to a limiting magnitude of 12.7.
Duration and limiting magnitude were additionally confirmed by Schmidt.  The
three occultation chords, as observed from Calgary (Alberta), were of lengths
8.3 +/- 1.0, 10.0 +/- 0.2, and 5.6 +/- 0.3 km, respectively, with chord
separations of 8.0 and 11.4 km.  The diameter of (5232) has been estimated to
be 11.563 +/- 0.211 km and 12.64 +/- 0.52 km (formal errors) by NEOWISE and
AKARI, respectively, giving estimated cross-sectional areas of 105.0 and 125.5
km**2.  The fading of 2.69 magnitudes excludes the possibility of a double
star, with the individual stars being occulted at the observers' locations.
An elongated single-body model similar to those of (216) Kleopatra (aspect
ratio 3.5) and (433) Eros (aspect ratio 2.5) can be excluded due to the highly
elongated shape required to fit the observations (length 45.0 km; aspect ratio
9.2), and also due to the equivalent cross-sectional area of 172.0 km**2,
which is far greater than the range of areas indicated in the NEOWISE and
AKARI surveys (105.0-125.5 km**2).  If, however, the three occultation chords
were due to two spherical bodies of diameter 10.0 and 8.3 km, the diameter of
the cross-sectional area of two components combined (13.0 km) falls within the
range of the NEOWISE and AKARI surveys.  Disappearance/reappearance (DR) times
observed by Yeung were approximately 3 s ahead of the predicted occultation
time, while DR times observed by Simpson were approximately 3 s behind; which
is further suggestive of a binary nature, with the mean DR being centered on
the predicted time.  Accordingly, the observation is consistent with (5232)
being a binary system.
     To further confirm the binary nature of this minor planet, P. Pravec
(Ondrejov Observatory, Astronomical Institute of the Academy of Sciences of
the Czech Republic) assessed the light curves previously recorded by R. Durkee
et al. (2016, Minor Planet Bull. 43, 284) and concluded that the data are
consistent with a fully synchronous binary system with rotation periods of the
two bodies equal to the orbital period.  R. Anderson, S. Deen, Durkee, S.
Preston, Pravec, and B. Warner provided assistance to the authors for this
analysis.  Light curve, data discussion, and fit data are posted at website
URL https://doi.org/10.17605/OSF.IO/FZM7K.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2024 CBAT
2024 April 17                    (CBET 5382)              Daniel W. E. Green