{
  "createdOn": 1682077438608,
  "circularId": 33666,
  "subject": "GRB 230420A: MITSuME Akeno optical observation",
  "eventId": "GRB 230420A",
  "body": "N. Higuchi, I. Takahashi, M. Sasada, S. Sato, R. Hosokawa, M. Niwano, Y.\nYatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on\nbehalf of the MITSuME collaboration:\n\nWe observed the field of GRB 230420A (N. J. Klingler et al. #33658, J.P.\nOsborne et al. #33661,R. Strausbaugh et al. #33662, Y.-D. Hu et al.\n#33663, S.Y.\nFu et al. #33664, S.Y. Fu et al. #33665) with the optical three color (g',\nRc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.\n\nThe observation with a series of 60 sec exposures started at 2023-04-20\n10:23:41 UT (280 seconds after the Swift/BAT detection). We stacked the\nimages with good conditions. Here we report the Rc and Ic band magnitudes\nby the forced-photometry at the enhanced Swift/XRT position (J.P. Osborne\net al. GCN Circular #33661), and the 5-sigma limit of the stacked images in\nthe g' band.\n\nT0+[sec] |MID-UT | T-EXP[sec] | magnitudes of forced-photometry\n\n------------------------------------------------------------------------------------------------\n\n 588 | 2023-04-20 10:28:49| 540 | g'>18.3, Rc=18.3+/- 0.3, Ic=17.3 +/- 0.2\n\n------------------------------------------------------------------------------------------------\n\nT0+ : Elapsed time after the burst\n\nT-EXP: Total Exposure time\n\nWe used PS1 catalog for flux calibration. The magnitudes are expressed in\nthe AB system. The images were processed in real-time through the MITSuME\nGPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages\n4-24; https://github.com/MNiwano/Eclaire).\n",
  "submitter": "Narikazu Higuchi at Tokyo Tech <higuchi@hp.phys.titech.ac.jp>",
  "bibcode": "2023GCN.33666....1H"
}