GCN Circular 29775
Subject
GRB 210406A: Mondy optical afterglow candidate
Date
2021-04-08T20:53:54Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP)
report on behalf of GRB IKI FuN:
We observed the field of GRB 210406A (Mereghetti et al., GCN 29767)
with AZT-33IK telescope of Sayan observatory (Mondy) in second epoch
starting on 2021-04-07 (UT) 16:54:14. The first epoch was obtained early
(Pankov et al., GCN 29770). We obtained 20 images in R-filter. In
comparison of the sources we found one fading source in coordinates of
(J2000) 08:49:49.09 76:33:20.2 with accuracy of 0.5 arcsec in each
coordinate. The source is faded by 0.5mag between the two epochs.
Preliminary photometry of the source in stacked images is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-04-06 17:54:58 0.04069 R 15*120 21.90 0.14 22.9
2021-04-07 16:54:14 0.98811 R 20*120 22.41 0.14 23.2
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id RA DEC R2
1665-0048950 132.414156 +76.555625 16.49
1664-0050141 132.551831 +76.468300 18.01
The source is not presented in Pan-STARRS PS1 but marginally visible in
Pan-STARRS (r-plate) and presented in Legacy Survey DR8.
We suggest the source as afterglow candidate of optical afterglow of GRB
210406A.