{
  "bibcode": "2022GCN.31893....1K",
  "body": "H. Kumar (IITB), V. Swain (IITB), R. Norbu (IAO), G. C. Anupama (IIA), S.\nBarway (IIA), V. Bhalerao (IITB), A. Dutta (IIA), R. Gupta (ARIES), K.\nMisra (ARIES), D. Panchal (ARIES), S.B. Pandey (ARIES), D.K. Sahu (IIA)\nreport on behalf of the HCT team:\n\n\nWe observed GRB 220408A detected by the Fermi-GBM (GCN # 31847), Swift-BAT\n(R. Caputo et al., GCN #31848) and optical afterglow discovered by Swift-UVOT\n(GCN #31848) with the 2.0m Himalayan Chandra Telescope (HCT) of the Indian\nAstronomical Observatory (IAO). We obtained multiple exposures in the Rc\nand Ic filters. We did not detect any new source in our stacked image at\nthe afterglow location.\n\nThe obtained upper limit follows as:\n\n-------------------------------------------------------------------------\n\n JD (mid) | T_mid-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) |\n\n-------------------------------------------------------------------------\n\n 2459678.203981 | 11.13 | 300 x 3 (stacked) | Rc | > 22.51 |\n\n 2459678.225509 | 11.64 | 300 x 3 (stacked) | Ic | > 22.46 |\n\n-------------------------------------------------------------------------\n\nOur upper limits are consistent with results from R. Caputo et al. (GCN\n#31848), W. Zheng and A.V. Filippenko (GCN #31850), S.Q. Jiang et al. (GCN\n#3185), S.R. Oates & R. Caputo (GCN #31855), H. Kumar et al. (GCN #31857),\nY.-D. Hu et al. (GCN #31859), R. Strausbaugh et al. (GCN #31862), Z. Zhu et\nal. (GCN #31864), G.S.H. Paek et al. (GCN #31867), A. Kumar et al. (GCN\n#31868), A.M. Watson et al. (GCN #31870), B. O'Connor et al. (GCN #31875),\nS. Beradze et al. (GCN #31884).\n\nThe magnitudes are in the AB system of magnitude, calibrated against\nPanSTARRS (Flewelling et al., 2018) using Lupton's transformation equations\navailable at\nhttp://classic.sdss.org/dr4/algorithms/sdssUBVRITransform.html#Lupton2005.\nThe magnitudes are not corrected for galactic extinction.\n\n\nThese observations were carried out under the ToO program HCT-2022-C1-P14\n(PI: Harsh Kumar). We thank the HCT staff for their support during the\nobservations. The Indian Astronomical Observatory is operated by the Indian\nInstitute of Astrophysics, Bengaluru, India.",
  "circularId": 31893,
  "createdOn": 1649839940000,
  "email": "harshkosli13@gmail.com",
  "subject": "GRB 220408A: HCT optical upper limit",
  "submitter": "Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>",
  "eventId": "GRB 220408A"
}