[Iaude] CBET 5318: (5457) QUEEN'S

quai at eps.harvard.edu quai at eps.harvard.edu
Wed Nov 15 22:52:52 EST 2023

                                                  Electronic Telegram No. 5318
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)
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Prepared using the Tamkin Foundation Computer Network

(5457) QUEEN'S
     J. Manek, Czech Astronomical Society; S. Dramonis, Athens, Greece; and C.
Weber, International Occultation Timing Association/European Section,
Hannover, Germany, report the discovery of the probable binary nature of the
minor planet (5457) via recording stellar occultations.  Manek (observing at
longitude 14d46'47".7, latitude +49d54'36".2, elevation 524 m) obtained a GPS-
time-stamped video observation (0.35-m Newtonian telescope + CMOS camera) of
an occultation of the star UCAC4 498-000768 (Gaia DR3 2750746718513211520) on
2023 Sept. 4.93059 UT; a drop of 1.666 s duration (primary body) was followed,
after 0.869 s, by a second drop of 0.200 s (presumed satellite).  The event
was also observed from five other sites (S. Meister in Switzerland; 2.404-s
chord but no satellite; A. Schweizer in Switzerland, 0.909-s chord but no
satellite; with no occultation seen by D. Antuszewicz in Poland, or by J.
Kubanek or M. Rottenborn in the Czech Republic).  None of these observations
contradict the satellite hypothesis.  On Sept. 20.00597 (15.07 days later),
Dramonis (longitude 23d33'50".9, latitude +38d37'6".4, elevation 342 m)
observed the presumed satellite during a GPS-time-stamped video observation
(0.40-m Newtonian telescope + CMOS camera) of the occultation of the star
UCAC4 493-000567 (Gaia DR3 source 2749281138232702080); in this single
observation, a drop of 0.222 s duration (satellite) was recorded.  After
1.631 s, there followed the 1.435-s drop of the primary body.  In both
occultation events, the double drops were of similar brightness and reached a
depth close to the limiting magnitude of the videos.  The deepness of the
corresponding magnitude drops rules out explanations that the occulted stars
are double stars not yet known.  In addition, atmospheric effects or noise
were ruled out as the cause of the secondary drops observed in both
occultations.  Using Occult4 sky-plane plots (D. Herald and D. Gault, via
website URL http://www.lunar-occultations.com/iota/occult4.htm), Weber et
al. reduced the occultation of Sept. 4 by an elliptical fit of the main body
to 24.6 (+/- 0.9) km x 16.2 (+/- 0.7) km, and of the satellite to 2.0 x 2.0
(+/- 0.2) km.  The occultation event on Sept. 20 resulted in a chord of 17.5
+/- 0.5 km for the primary body and a chord of 2.8 +/- 0.5 km for the
presumed satellite.  Assuming that the secondary bodies in both observations
have circular profiles with the above diameters, the following J2000.0
positions of the satellite relative to the main body were derived:  2023
Sept. 4.93059, separation 11.4 +/- 0.7 mas in p.a. 52.2 +/- 3.0 degrees;
Sept. 20.00597, separation 20.4 +/- 0.5 mas in p.a. 248.8 +/- 3.0 degrees.
To improve the results found and to facilitate follow-up observations, the
authors have identified upcoming stellar occultations by (5457); these
predictions will be part of an article in the Minor Planet Bulletin.  The
authors acknowledge Herald and Gault (both in the Trans-Tasman Occultation
Alliance) for an independent assessment of these data.

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

                         (C) Copyright 2023 CBAT
2023 November 16                 (CBET 5318)              Daniel W. E. Green

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