TITLE:   GCN CIRCULAR
NUMBER:  27593
SUBJECT: GRB 200412B: continued Tautenburg observations 
DATE:    20/04/16 14:25:46 GMT
FROM:    Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>

S. Klose, B. Stecklum, S. Melnikov, and A. Nicuesa Guelbenzu (all 
Tautenburg) report:

We continued observing the field of GRB 200412B (Fermi GBM team, GCN 
27547) with the Tautenburg 1.34m Schmidt telescope equipped with the 
TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB; Stecklum et al., 
GCN 27567, 27582; Klose et al., GCN 27575).

For the optical transient (Lipunov et al., GCN 27555, 27556) at a mean 
time of 3.53 days post burst we measure VB = 22.29 +/- 0.11. This confirms 
the suspected steepening of the light curve decay (Stecklum et al., GCN 
27582). Our present VB-band data imply alpha2 = 2.52 +/- 0.02 and a break 
time of 2.04 +/- 0.02 days.