Electronic Telegram No. 5512
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


(6326) IDAMIYOSHI
     K. Miyashita (Azumino, Nagano, Japan) reports that H. Watanabe
(Nachikatsuura, Wakayama, Japan), H. Yamamura (Taiji, Wakayama, Japan), and N.
Manago (Kamitonda, Wakayama, Japan) have discovered the apparent binary nature
of the minor planet (6326) from the occultation of the star UCAC4 525-004262
(magnitude 12.4) on 2024 Aug. 21.782 UT.  The minor planet was 5.5 magnitudes
fainter than the star.  Watanabe recorded a full-light-drop occultation of
duration 1.07 s, followed 0.39 s later by a 74-percent light drop lasting 0.10
s.  Both light drops were greater than 2.4 magnitudes, to below the brightness
of a 14.8-mag comparison star.  The depth of these light drops excludes the
possibility of this being a double star with different components occulted at
Watanabe's location.  Yamamura recorded a full-light-drop occultation of
duration 1.13 s, followed 0.27 s later by a 33-percent light drop lasting 0.13
s.  The location corresponding to this light drop was fully consistent with
the location of the second light drop of Watanabe, indicating that it was
caused by the same body having a diameter of 1.3 km.  Miyashita modeled the
effect of Fresnel diffraction and found that the depths of the second light
drop for both observers were consistent with Fresnel diffraction of a 1.3-km
body.  The diameter of the main body is constrained by a "miss" observation in
Manago's data, with a major axis of 8.8 km and a minor axis no greater than
7.0 km, giving a mean diameter no greater than 7.8 km.  The distance to the
satellite was 7.7 km in p.a. 277 degrees.  The chords are displayed in a
diagram at http://www.cbat.eps.harvard.edu/iau/cbet/005500/CBET5512_Fig1.png
(provided by Miyashita).  D. Herald (Murrumbateman, Australia), who aided in
the analyses of these data, provides an additional chord diagram, posted at
URL http://www.cbat.eps.harvard.edu/iau/cbet/005500/CBET5512_Fig2.png, and
two light-curve plots for Yamamura's and Watanabe's observations posted at
URL http://www.cbat.eps.harvard.edu/iau/cbet/005500/CBET5512_Fig3.png;
explanation of the figures follows that provided on CBET 5511.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2025 CBAT
2025 February 26                 (CBET 5512)              Daniel W. E. Green