GCN Circular 9218
Subject
GRB 090423: Near infrared observation at Okayama Observatory
Event
Date
2009-04-24T04:03:34Z (17 years ago)
From
Michitoshi Yoshida at Okayama Astrophysical Obs <yoshida@oao.nao.ac.jp>
M. Yoshida, K. Yanagisawa, D. Kuroda, Y. Shimizu, S. Nagayama,
H. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf
of the MITSuME collaboration:
We observed the field of GRB 090423 (Krimm et al. GCN 9198) with a
near-infrared camera ISLE attached to the 188cm telescope of Okayama
Astrophysical Observatory. We also obtained optical data using the
optical three color CCD camera attached to the MITSuME 50cm
telescope.
We started the observation at 2009-04-23 10:32:27 UT, 2hr 37m after
the burst. We detected a very faint source close to the position of
the afterglow candidate reported by Tanvir et al. (GCN 9202) in our
J band image. The coordinate of the source is
J2000.0 9h 55m 33.3s +18d 08m 57.1s .
J band magnitude of the source is 20.1 mag, which is much fainter
than the previous report (Cucchiara et al. GCN 9213).
We could not find any new source in the optical bands and the other
near-infrared bands (H and Ks). The results of our photometry are
listed below. We used three 2MASS stars near the burst for near-
infrared flux calibration and GSC2.3 catalog for optical flux
calibration.
Near-infrared observation
Band Mid-UT Td(day) EXP-T mag
------------------------------------------------------
J 10:53:33 0.12377 720s 20.1 $B!^(B 0.3
H 11:04:30 0.13138 960s > 19.3
Ks 10:56:31 0.12584 480s > 18.7
------------------------------------------------------
Optical observation
Mid-UT Td(day) EXP-T g' Rc Ic
------------------------------------------------------------
11:43:56 0.15876 5940s >20.4 >20.2 >19.5
------------------------------------------------------------