Electronic Telegram No. 5524
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


(1626) SADEYA
     J. Hanus, Charles University, Prague; F. Marchis, Unistellar/SETI
Institute; and P. Pokorny, Catholic University of America, report the
detection of an apparent satellite near minor planet (1626) via a stellar
occultation observed by Unistellar network citizen astronomer Van Ruckman
on 2025 Jan. 3 UT from Kingsmill on the James in Williamsburg, VA, USA,
using an eVscope v2.0 telescope (+ unfiltered IMX347 CMOS camera).  The
observation appears to confirm the presence of the satellite previously
suggested by lightcurve data (cf. CBET 4893).  The stellar-occultation event
revealed two distinct bodies.  The primary body caused a 0.9-s occultation,
corresponding to a minimal spherical diameter of approximately 11.7 km.  The
satellite was detected 4.2 s earlier (disappearance at 0h12m58s.46 UT on Jan.
3, and reappearance at 0h12m59s.36), with an occultation duration of 0.3 s,
corresponding to a minimal spherical diameter of approximately 3.9 km.  The
projected separation between the primary and the satellite during the event
was approximately 54.5 km.  Figure 1 shows the lightcurve produced with
Asteroid Occultation Timing Analysis (AOTA) software, showing the drop in
brightness during the occultation event caused by the primary body of (1626)
Sadeya; blue data points represent the measured flux over time, and red lines
indicate the start and end of the detected dip (posted at website URL
http://www.cbat.eps.harvard.edu/iau/cbet/005500/CBET5524_Fig1.png). Figure 2
(cf. URL http://www.cbat.eps.harvard.edu/iau/cbet/005500/CBET5524_Fig2.png)
is the AOTA lightcurve, highlighting the dip caused by the secondary
(satellite).  These results further support the binary nature of (1626),
providing direct measurements of the minimal sizes and separation of the
system components.  Such observations highlight the importance of occultation
data for characterizing binary-asteroid systems.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2025 CBAT
2025 March 12                    (CBET 5524)              Daniel W. E. Green