TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2730
SUBJECT: XRF040916: continuing decay of OT
DATE:    04/09/21 12:09:48 GMT
FROM:    George Kosugi at Subaru Telescope  <george@subaru.naoj.org>

G. Kosugi, N. Kawai, A. Tajitsu, and H. Furusawa
        on behalf of the Subaru GRB Team:

We have observed the entire HETE error box for XRF040916 (=H3558,
Yamazaki et al., GCN 2712; Yamamoto et al. GCN 2713), with Subaru
Suprime Cam beginning at around 6:00 UT on September 20, 2004 in
z'-, Ic-, Rc-, V-, and B-bands.  The observed field was centered
at the proposed OT candidate reported by Kosugi et al. GCN 2726.

The OT was clearly detected in all 5 bands, and shows apparent
decay of flux in Ic-, Rc-, and B-bands compared with our
previous observations on September 18.  Rc-band magnitude of OT
at Septempber 20.43 UT was approximately Rc=25.

Composite color images are posted at:
http://www.naoj.org/staff/george/Distribute/XRF040916/XRF040916.html
OT is located at the center of the images.

Due to change of instruments, we cannot continue optical monitoring of
OT with Subaru for the next two weeks.  Follow-up optical observation
of the OT is strongly encouraged for possible supernova rebrightening.

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