{
  "bibcode": "2021GCN.30856....1K",
  "body": "GRB 210919A: LOAO and LSGT optical upper limits\n\n\nSophia Kim (Seoul National University, SNU), Myungshin Im (SNU); Jeff Cooke\n(Swinburne University of Technology), Gu Lim (SNU); report on behalf of\nIMSNG & GECKO Collaboration\n\n\nWe carried out follow-up observations of GRB210919A (A. Tohuvanohu et al.\nGCNC #30846) with the 1-m telescope at Mt. Lemon Optical Astronomy\nObservatory (LOAO) in US Arizona. Observations began on September 19 at\n10:42:02 UT , ~10.23 hours after the GRB trigger. We took 19 X 180s\nexposures in Johnson R-band.\n\nWe also observed the same field with the 0.43-meter (17 inch) Lee Sang Gak\nTelescope (LSGT) located at the Siding Spring Observatory (SSO) in\nAustralia. Imaging began on the same day at 16:12:53 UT, ~15.73 hours after\nthe GRB trigger. The observations were performed in a Sloan r-, i- and\nz-band sequences with 11 X  300s exposures in each band.\n\n\nNo GRB optical counterpart was found in the LOAO and LSGT data within the\nXRT error area (M. R. Goad et al. GCNC #30850). This result is consistent\nwith the optical observational results by other teams (V. Lipunov et al.\nGCNC #30847, Y.-D. Hu et al. GCNC #30848, R. Strausbaugh et al. GCNC\n#30849, M.R. Goad et al. GCNC #30850, N. Pankov et al. GCNC #30851, D. A.\nPerley et al. GCNC #30852, M. Perri et al. GCNC #30854 and Y.Takamatsu et\nal. GCNC #30855).\n\n\nThe following is our observation results.\n\nWe calibrated flux with the PS1 catalog and used AB magnitude system. (The\nmagnitudes are not corrected for extinction.)\n\n\n#--------------------------------------------------------------------------------------------------------------\n\nOBS/TEL DATE-OBS(UT) FILTER EXPT UL(3��)[ABmag] UL(5��)[ABmag]\n\nLOAO/1-m 2021-09-19T10:42:02 R 3420s >21.716  >21.162\n\nSSO/LSGT 2021-09-19T16:12:53 r 3300s >20.160  >19.605\n\nSSO/LSGT 2021-09-19T16:18:17 i 3300s >19.107  >18.553\n\nSSO/LSGT 2021-09-19T16:23:53 z 3300s >18.674  >18.119\n\n--------------------------------------------------------------------\n\n[GCN OPS NOTE(20sep2021):  Per author's request, the signiture block\nthat is automatically added to the bottom has been removed.]",
  "circularId": 30856,
  "createdOn": 1632124838000,
  "email": "sophiak@astro.snu.ac.kr",
  "subject": "GRB 210919A: LOAO and LSGT optical upper limits",
  "submitter": "Sophia Kim at Seoul National U.  <sophiak@astro.snu.ac.kr>",
  "eventId": "GRB 210919A"
}