{
  "bibcode": "2021GCN.29775....1B",
  "body": "S. Belkin (IKI), N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP) \nreport  on behalf of GRB IKI FuN:\n\nWe observed the field of GRB 210406A (Mereghetti  et al., GCN 29767) \nwith AZT-33IK telescope of Sayan observatory (Mondy) in second epoch \nstarting on 2021-04-07 (UT) 16:54:14. The first epoch was obtained early \n(Pankov  et al., GCN 29770). We obtained 20 images in R-filter. In \ncomparison of the sources we found one fading source in coordinates of \n(J2000) 08:49:49.09    76:33:20.2 with accuracy of 0.5 arcsec in each \ncoordinate. The source is faded by 0.5mag between the two epochs. \nPreliminary photometry of the source in  stacked images is following\n\nDate       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)\n                     (mid, days)        (s)\n\n2021-04-06 17:54:58   0.04069    R     15*120  21.90  0.14  22.9\n2021-04-07 16:54:14   0.98811    R     20*120  22.41  0.14  23.2\n\nThe photometry is based on the nearby USNO-B1.0 stars\nUSNO-B1.0_id RA DEC R2\n1665-0048950 132.414156 +76.555625 16.49\n1664-0050141 132.551831 +76.468300 18.01\n\nThe source is not presented in Pan-STARRS PS1 but marginally  visible in \nPan-STARRS (r-plate) and presented in Legacy Survey DR8.\n\nWe suggest the source as afterglow candidate of optical afterglow of GRB \n210406A.",
  "circularId": 29775,
  "createdOn": 1617915234000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 210406A: Mondy optical afterglow candidate",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 210406A"
}