TITLE: GCN CIRCULAR NUMBER: 24089 SUBJECT: GRB 190404C: MITSuME Akeno and Okayama optical upper limits DATE: 19/04/10 11:53:08 GMT FROM: Adachi Ryo at Tokyo Institute of Tech R. Adachi, M. Niwano, K. L. Murata, K. Iida, M. Oeda, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We performed tiling observation for the error region of GRB 190404C (S. Yamada et al., GCN Circular #24049) with an optical tri-color (g', Rc, and Ic) camera attached to the MITSuME 50cm telescopes at Akeno Observatory and Okayama Astrophysical Observatory, in Japan. The follow up observation started at 2019-04-04 13:36:27 UT, 1,339 sec after the trigger. Our tiling observation covered almost 95% of the MAXI/GSC error box (S. Yamada et al., GCN Circular #24049). We did not find any new point source within the Swift XRT error circle (P. D'Avanzo et al. GCN #24054, #24062) in all three bands. Since the brightness source near the XRT error circle(~9 arcsec), the obtained upper limit is very shallow. The obtained 5 sigma upper limits of the optical counterpart are summarize below: T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------- 1339 13:42:06 480 >13.1 >12.4 >11.9 ------------------------------------------------------------------------------------------------------- Furthermore, compared our co-added images with GSC2.3 catalog and UCAC4 catalog, we found no bright optical transient in the observed region. Because the sky condition was unstable, the obtained upper limits are different for each field. The 5-sigma upper limits of the co-added images are listed below. Field num. center position(R.A., Dec.) size of field(R.A.(arcmin) x Dec.(arcmin)) 5-sigma upper limit start observation time(UT) -------------------------------------------------------------------------------------------- Field 1 14:42:36, -22:46:14 25.7 x 25.9 g' > 17.0, Rc > 17.2, Ic > 17.1 13:36:27 Field 2 14:43:08, -22:37:04 25.7 x 25.9 g' > 17.4, Rc > 17.6, Ic > 17.4 13:47:51 Field 3 14:43:03, -22:14:27 26.0 x 25.0 g' > 17.8, Rc > 18.0, Ic > 17.5 14:47:19 Field 4 14:44:50, -22:41:11 23.3 x 23.7 g' > 15.6, Rc > 15.6, Ic > 15.7 14:47:06 Field 5 14:41:24, -22:15:23 23.3 x 24.3 g' > 18.0, Rc > 18.0, Ic > 17.5 16:24:11 Field 6 14:42:17, -22:30:00 24.0 x 23.6 g' > 18.1, Rc > 18.1, Ic > 17.5 17:57:11 Field 7 14:43:12, -22:17:05 25.4 x 25.7 g' > 17.2, Rc > 17.3, Ic > 17.1 15:46:23 Field 8 14:44:14, -22:27:57 25.8 x 25.9 g' > 17.7, Rc > 17.3, Ic > 16.9 18:25:06 Field 9 14:41:18, -22:20:50 25.4 x 25.7 g' > 17.6, Rc > 17.7, Ic > 17.1 19:28:34 Field 10 14:43:18, -22:41:18 23.3 x 23.7 g' > 18.4, Rc > 18.4, Ic > 17.7 15:25:47 -------------------------------------------------------------------------------------------- We used UCAC4 catalog for flux calibration.