TITLE:   GCN CIRCULAR
NUMBER:  29644
SUBJECT: GRB 210306A: Tautenburg observations
DATE:    21/03/10 14:33:10 GMT
FROM:    Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>

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

We continued observations of the field of GRB 210306A (D'Elia et al., GCN 
29597) with the Tautenburg 1.34m Schmidt telescope. For the optical 
afterglow (Simpson & D'Elia, GCN 29636; Belkin et al., GCN 29635, and 
references therein) we measure:

March 07, 00:21 UT : Rc  = 20.47 +/- 0.13  (Vega mag)

March 07, 02:12 UT : Rc  = 20.53 +/- 0.14

March 07, 19:34 UT : Rc  > 21.2.


Data calibration followed Stecklum et al. (GCN 29604).