GCN Circular 29890
Subject
GRB 210420B: continued Tautenburg observations
Date
2021-04-23T10:03:42Z (3 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
A. Nicuesa Guelbenzu, S. Klose, S. Melnikov, B. Stecklum, and U. Laux (all
Tautenburg) report:
We continued observing the afterglow of GRB 210420B (Moss et al., GCN
29844) with the Tautenburg 1.34m Schmidt telescope equipped with the
TAUKAM 6k x 6k CCD camera.
Results are:
- run 2: midtime 01:35 UT, April 22: r' = 21.40 +/- 0.20 mag
- run 3: midtime 23:24 UT, April 22: r' > 22.7 (3 sigma)
Magnitudes were calibrated against SDSS stars in the field.
Our data (see Stecklum et al., GCN 29863) imply that between the 2nd and
the 3rd observing run the decay of the light curve has steepened from
alpha = 0.99 +/- 0.04 to alpha = 2.3 +/- 0.9, with a break time at 1.14
+/- 0.29 days. Probably this is the classical jet break time. No further
observations are planned.