TITLE: GCN CIRCULAR NUMBER: 31776 SUBJECT: GRB 220319A: MITSuME Akeno optical upper limits DATE: 22/03/20 16:06:24 GMT FROM: Ryohei Hosokawa at Tokyo Institute of Technology R. Hosokawa, Y. Imai, K. L. Murata, M. Niwano, N. Ito, Y. Takamatsu, R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 220319A (K. L. Page et al. GCN Circular #31769, V.Lipunov et al. GCN Circular #31770, M.R. Goad et al. GCN Circular #31771, J. D. Gropp et al. GCN Circular #31772, S. Belkin et al. GCN Circular #31773, R. Strausbaugh et al. GCN Circular #31774, A. de Ugarte Postigo et al. GCN Circular #31775) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno. The observation with a series of 10 sec exposures started at 2022-03-19 17:41:30 UT (56.7 seconds after Swift BAT trigger). We stacked the images with good conditions. We did not detect any sources within the XRT error region (M.R. Goad et al. GCN Circular #31771). We obtained the 5-sigma limits of the stacked images as follows. T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits ------------------------------------------------------------- 101 | 2022-03-19 17:42:14 | 50 | g'>17.0, Rc>16.8, Ic>16.5 762 | 2022-03-19 17:53:16 | 560 | g'>18.5, Rc>18.3, Ic>17.9 4925 | 2022-03-19 19:02:38 | 5520 | g'>19.8, Rc>19.9, Ic>19.6 ------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).