{
  "bibcode": "2022GCN.31776....1H",
  "body": "R. Hosokawa, Y. Imai, K. L. Murata, M. Niwano, N. Ito, Y. Takamatsu,\nR. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai\n(Tokyo Tech) report on behalf of the MITSuME collaboration:\n\nWe observed the field of GRB 220319A (K. L. Page et al. GCN Circular\n#31769, V.Lipunov et al. GCN Circular #31770, M.R. Goad et al. GCN\nCircular #31771, J. D. Gropp et al. GCN Circular #31772, S. Belkin et\nal. GCN Circular #31773, R. Strausbaugh et al. GCN Circular #31774, A.\nde Ugarte Postigo et al. GCN Circular #31775) with the optical three\ncolor (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm\ntelescope Akeno. The observation with a series of 10 sec exposures\nstarted at 2022-03-19 17:41:30 UT (56.7 seconds after Swift BAT\ntrigger). We stacked the images with good conditions. We did not\ndetect any sources within the XRT error region (M.R. Goad et al. GCN\nCircular #31771). We obtained the 5-sigma limits of the stacked images\nas follows.\n\nT0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits\n-------------------------------------------------------------\n101  | 2022-03-19 17:42:14 | 50   | g'>17.0, Rc>16.8, Ic>16.5\n762  | 2022-03-19 17:53:16 | 560  | g'>18.5, Rc>18.3, Ic>17.9\n4925 | 2022-03-19 19:02:38 | 5520 | g'>19.8, Rc>19.9, Ic>19.6\n-------------------------------------------------------------\nT0+ : Elapsed time after the burst\nT-EXP: Total Exposure time\n\nWe used PS1 catalog for flux calibration.\nThe magnitudes are expressed in the AB system.\nThe images were processed in real-time through the MITSuME GPU\nreduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages\n4-24; https://github.com/MNiwano/Eclaire).",
  "circularId": 31776,
  "createdOn": 1647792384000,
  "email": "hosokawa@hp.phys.titech.ac.jp",
  "subject": "GRB 220319A: MITSuME Akeno optical upper limits",
  "submitter": "Ryohei Hosokawa at Tokyo Institute of Technology  <hosokawa@hp.phys.titech.ac.jp>",
  "eventId": "GRB 220319A"
}