{
  "bibcode": "2022GCN.32730....1S",
  "body": "M. Sasada, Y. Imai, K. L. Murata, R. Hosokawa, M. Niwano, I.Takahashi,\nM. Tateda, N. Ito, S. Sato, N. Higuchi, Y. Yatsu, and N. Kawai (Tokyo\nTech) report on behalf of the MITSuME collaboration:\n\nWe observed the field of GRB 221009A (Dichiara et al. #32632, Kennea\net al. #32635, Veres et al. #32636, Bissaldi et al. #32637, Perley et\nal. #32638, Broens et al. #32640, Svinkin et al. #32641, Lesage et al.\n#32642, Karambelkar et al. #32643, Hu et al. #32644, Belkin et al.\n#32645, Wet et al. #32646, Xu et al. #32647, Postigo et al. #32648,\nUrsi et al. #32650, Kennea et al. #32651, Brivio et al. #32652, Bright\net al. #32653, Durbak et al. #32654, Farah et al. #32655, Piano et al.\n#32657, Pillera et al. #32658, Paek et al. #32659, Gotz et al. #32660,\nXiao et al.#32661, Kumar et al. #32662, Lapshov et al. #32663, Romanov\net al. #32664, The IceCube Collaboration et al. #32665, Odeh et al.\n#32666, Chen et al. #32667, Frederiks et al. #32668, Vidal et al.\n#32669, Kim et al. #32670, Tohuvavohu et al. #32671, Postigo et al.\n#32676, Huang et al. #32677, Groot et al. #32678, Romanov et al.\n#32679, Tiengo et al. #32680, Ayala et al. #32683, Belkin et al.\n#32684, Ripa et al. #32685, Castro-Tirado et al. #32686, Krimm et al.\n#32688, Negro et al. #32690, Savchenko et al. #32691, Watson et\nal.#32692, Strausbaugh et al. #32693, Iwakiri et al. #32694, Brethauer\net al. #32695, Rhodes et al. #32700, Butler et al. #32705, Rhodes et\nal. #32707, Vinko et al. #32709, Mao et al. #32727, Zaznobin et al.\n#32729) with the optical three color (g', Rc, and Ic) CCD cameras\nattached to the MITSuME 50 cm telescope Okayama.\n\nThe observation with a series of 60 sec exposures started at\n2022-10-09 9:51:38 UT (0.857 day after the Swift detection). We\nstacked the images with good conditions. Here we report a Ic-band\nmagnitude by the forced-photometry at the Swift/UVOT position\n(Dichiara et al. GCN Circular #32632), and the 5-sigma limits of the\nstacked images in the g' and Rc bands.\n\nT0+[day] |MID-UT | T-EXP[sec] | magnitudes of forced-photometry\n------------------------------------------------------------------------------------------------\n0.9320 | 2022-10-10 11:39:09| 8340 | g'>18.3, Rc>17.0, Ic=17.1+/-0.2\n------------------------------------------------------------------------------------------------\nT0+ : Elapsed time after the burst\nT-EXP: Total Exposure time\n\nWe used PS1 catalog for flux calibration. The magnitudes are expressed\nin the AB system. The images were processed in real-time through the\nMITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,\nIssue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).",
  "circularId": 32730,
  "createdOn": 1665647936000,
  "email": "imai@hp.phys.titech.ac.jp",
  "subject": "GRB 221009A: MITSuME Okayama optical observation",
  "submitter": "Yuri Imai at Tokyo Inst of Tech  <imai@hp.phys.titech.ac.jp>",
  "eventId": "GRB 221009A"
}