{
  "bibcode": "2023GCN.33547....1R",
  "body": "Amit K. Ror, Rahul Gupta, S. B. Pandey, A. Ghosh, A. Aryan, and K. Misra\n(ARIES) report:\n\nGRB 230328B was triggered by Swift-BAT at 14:54:48 UT and Fermi-GBM at\n14:54:47.43 UT on 28-03-2023 (Gropp et al. 2023 GCN 33527, Dalessi et al.\n2023 GCN 33531). The prompt emission was also detected by other space-based\nfacilities like AstroSat-CZTI (Waratkar et al. 2023, GCN 33532), GRBAlpha\n(Dafcikova et al. 2023, GCN 33543), and Konus-Wind (Svinkin et al. 2023,\nGCN 33544). We searched for extended GeV emission for a temporal window of\n10 ks since the GBM trigger, based on available LAT data. However, we did\nnot find the detection of any GeV photons, and an upper limit was obtained\nfor an energy flux < 5.2 x 10^{-10} erg/cm2/s in the energy range 100 MeV -\n100 GeV with TS < 20.\n\nWe observed the field of GRB 230328B using the 3.6m Devasthal Optical\nTelescope located at the Devasthal observatory of the Aryabhatta Research\nInstitute of Observational Sciences (ARIES), Nainital, India. We have taken\nmultiple frames with an exposure time of 300 sec each in several optical\npassbands. We clearly detect the optical afterglow discovered by Swift-UVOT\nin each individual image. The estimated preliminary magnitude is as follows:\n\nDate Start_UT T_start-T0 (days) Filter  Exp time (sec)       magnitude\n\n==============================================================\n\n2023-03-28 21:51:54.44   ~0.29          R         300 sec  20.30 +/- 0.08\n\nThe magnitude quoted is not corrected for the galactic and host extinctions\nin the direction of the burst. Photometric calibration is performed using\nthe standard stars from the USNO-B1 catalog.\n\nThe detection of the optical afterglow is consistent with the observation\nof Gropp et al. 2023 (GCN 33527), Pankov et al. 2023 (GCN 33528), Belkin et\nal. 2023 (GCN 33530), Lu et al. 2023 (GCN 33534), Catapano et al. (33535),\nSuresh et al. (GCN 33536), Adami et al. (GCN 33537), Gompertz et al. (GCN\n33538), Komesh et al. (GCN 33539), Lu et al. 2023 (GCN 33540)\n\nBy combining our R-band magnitude with the observations of Pankov et al.\n2023 (GCN 33528) and Belkin et al. 2023 (GCN 33530), we have determined the\npreliminary flux decay index of 0.55 +/-0.06.\n\nThis circular may be cited. The 3.6m Devasthal Optical Telescope (DOT) is a\nrecently commissioned facility in the Northern Himalayan region of India\n(long: 79 41 04E, lat: 29 21 40N, alt: 2540m) owned and operated by\nthe Aryabhatta\nResearch Institute of Observational Sciences (ARIES), Nainital (\nhttps://www.aries.res.in). The authors of this GCN circular thankfully\nacknowledge the consistent support from the staff members to run and\nmaintain the 3.6m DOT.",
  "circularId": 33547,
  "createdOn": 1680248988000,
  "email": "mitturor77894@gmail.com",
  "subject": "GRB 230328B: 3.6m DOT multiband optical observation",
  "submitter": "Amit Kumar Ror at ARIES  <mitturor77894@gmail.com>",
  "eventId": "GRB 230328B"
}