{
  "bibcode": "2022GCN.32460....1D",
  "body": "S. de Wet (UCT), P.J. Groot (Radboud/UCT/SAAO), D. Pieterse (Radboud), P.M.\nVreeswijk (Radboud), A.J. Levan (Radboud) and D.B. Malesani (Radboud and\nDAWN/NBI) report on behalf of the MeerLICHT consortium:\n\nFollowing the detection of GRB 220810A by Fermi/GBM (Fermi GBM team, GCN\n32455), the 0.6 m wide-field MeerLICHT optical telescope began a series of\nautomatically-triggered 60 s q-band exposures of a number of fields\nencompassing the GBM error box. Observations began approximately 14 minutes\npost-trigger at 23:30:01 UT on 2022 August 10, and continued for an hour.\n\nA total of 20 fields encompassing a cumulative probability of 58% were\nobserved once each. Within our difference-imaging products for this dataset\nwe identify two new transient candidates with the following coordinates,\nbrightness, and observing times:\n\n+---------------------------+-------------------------+----------------+------------------+----------+\n| RA (J2000)                | Dec (J2000)             | Mag (AB)       |\n5-sigma limiting | UT time  |\n|                           |                         |                |\n mag (AB)        |          |\n+---------------------------+-------------------------+----------------+------------------+----------+\n| 20:45:15.77 (311.31569d)  | +05:06:39.95 (5.11110d) | 11.51 +/- 0.06 | q\n> 15.79        | 23:59:19 |\n+---------------------------+-------------------------+----------------+------------------+----------+\n| 20:49:24.58 (312.35241d)  | +01:56:09.64 (1.93601d) | 17.52 +/- 0.07 | q\n> 18.77        | 23:44:42 |\n+---------------------------+-------------------------+----------------+------------------+----------+\n\nThese positions are calibrated against Gaia DR2 with a positional\nuncertainty of 0.1\" in each coordinate. We note that the first, bright\ncandidate was identified in an image in which the sources are trailed.\nHowever, human inspection confirms that the source is not an artefact.\n\nThe position of both transients is within the 50% probability region of the\nGBM error box, and no objects consistent with these positions and observing\ntimes were found in the Minor Planet Centre database. We also note that no\nunderlying source is visible in archival PanSTARRS images at these\npositions.\n\nWe obtained further observations of the second, fainter source on the\nfollowing night and obtained a 5-sigma limiting magnitude of q > 19.22 at\nthe transient position, consistent with fading behaviour. Further follow-up\nobservations are encouraged in order to determine if either of these\nsources is the afterglow of GRB 220810A.\n\nMeerLICHT is built and run by a consortium consisting of Radboud\nUniversity, the University of Cape Town, the South African Astronomical\nObservatory, the University of Oxford, the University of Manchester and the\nUniversity of Amsterdam.",
  "circularId": 32460,
  "createdOn": 1660317808000,
  "email": "dwtsim002@myuct.ac.za",
  "subject": "GRB 220810A: MeerLICHT detection of two afterglow candidates",
  "submitter": "Simon de Wet at UCT  <dwtsim002@myuct.ac.za>",
  "eventId": "GRB 220810A"
}