TITLE:   GCN CIRCULAR
NUMBER:  16151
SUBJECT: GRB 140423A: KWFC z-band photometry
DATE:    14/04/23 13:55:20 GMT
FROM:    Nozomu Tominaga at Konan U  <tominaga@konan-u.ac.jp>

Hiroyuki Maehara (Univ. of Tokyo), Nozomu Tominaga (Konan Univ.), Tomoki Morokuma (Univ. of Tokyo) and Masaomi Tanaka (NAOJ) on
behalf of OISTER collaboration:

We observed the field of GRB 140423A (Sonbas et al., GCN 16142) with the 1.05-m Schmidt telescope and KWFC (Sako et al. 2012, Proc.
SPIE 8446, 84466L) at Kiso Observatory in Japan.

The observation was made in the Sloan z-band at 2014-04-23 10:30 (UT), approximately 2 hours post burst. 

We have also detected the optical source (Elenin et al., GCN 16143, 16148; Kaur et al. GCN 16144; Ferrante et al., GCN 16145;
Chester et al., GCN 16147) at RA=13:09:08.54, DEC=+49:50:29.3 (J2000).　Preliminary photometry of the source is as follows.

obs. date (mid time)  Tmid-T0 (hr)  exp. time   filter      mag      limiting mag
2014-04-23 10:30:11     1.97         300 sec      z      18.6+/-0.1     19.5

The photometry is based on z-mag of SDSS stars in the observed field.