GCN Circular 29770
Subject
GRB 210406A: Mondy optical upper limit
Date
2021-04-07T10:25:25Z (3 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE), S. Belkin (IKI), 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) starting on
2021-04-06 (UT) 17:54:58. We obtained 15 images in R-filter. We do not
find new sources in a stacked image in comparison with Pan-STARRS PS1 or
Legacy Survey which is consistent with observations (Lipunov et al., GCN
29766; Hu et al., GCN 29768; Vinko et al., GCN 29769). So we have no
immediate OT candidate. More observation is necessary to investigate
variability of field sources.
Preliminary photometry of the field in the stacked image 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 n/d n/d 22.9
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