GCN Circular 16151
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).$B!!(BPreliminary 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.