GCN Circular 21249
Subject
LIGO/Virgo G288732: Kiso/KWFC optical imaging of the possible Fermi/LAT counterpart
Date
2017-06-12T11:26:22Z (8 years ago)
From
Tomoki Morokuma at U.TokyoJ-GEM <tmorokuma@ioa.s.u-tokyo.ac.jp>
Tomoki Morokuma (The University of Tokyo), Masaomi Tanaka (National
Astronomical Observatory of Japan), Nozomu Tominaga (Konan University),
Shigeyuki Sako, Ryou Ohsawa, Mamoru Doi, Kentaro Motohara (The
University of Tokyo) on behalf of J-GEM collaboration
We report optical imaging follow-up observations in an error region of
the possible electromagnetic counterpart of G288732 (GCN 21221)
discovered with Fermi LAT (Omodei et al. 2017, GCN, 21227). We observed
the field with 1.05-m Kiso Schmidt telescope and its 2.2 deg x 2.2 deg
field-of-view camera, Kiso Wide Field Camera (KWFC; Sako et al. 2012,
SPIE, 8446, 84466L). We took two consecutive 1-sec exposures twice in
i-band on June 9.483, 9.489, 9.527, and 9.529, 2017 UT, roughly 123 ks
after the GW detection. The median depth of the images is 15.6 mag (AB,
5 sigmas). Although there is a 1.5 arcmin gap in Declination because of
the spatial gap of the CCDs, we covered almost the entire error field of
the possible Fermi LAT detection. We compared the detected source
catalogs with the public Pan-STARRS1 catalog (Chambers et al. 2016,
arXiv:1612.05560) and do not find any new transient sources within the
Fermi LAT error circle. All the seven Swift XRT sources reported
in Evans et al. (2017, GCN 21233) were covered by our observations and
the source 7 is detected in our images with almost constant brightness
of i=12.8 mag.
[GCN OPS Note(14jun17): Per author's request, the phase
"were covered by our observations" was added to the last sentence.]