[vsnet-grb-info 16249] GRB 150301B: LCOGT-Sutherland observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17530
SUBJECT: GRB 150301B: LCOGT-Sutherland observations
DATE:    15/03/02 09:00:17 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi (U. Ferrara), J. Japelj, A. Gomboc (U. Ljubljana),
C.G. Mundell (U. Bath), on behalf of a large collaboration report:

One of the Las Cumbres Observatory 1-m telescopes in Sutherland
(South Africa) began observing Swift and Fermi GRB 150301B
(Lien et al. GCN 17515; Burns et al. GCN 17525) on March 01
at 20:07:30 UT, i.e. ~29.4 minutes after the BAT trigger
with the r', i', and g' filters.

We detect the optical afterglow (Lien et al. GCN 17515;
Buckley et al. GCN 7518; Kann et al. GCN 17522; de Ugarte
Postigo et al. GCN 17523) with the following magnitudes:

Mid time from  Total Exp   Filter    Magnitude
trigger (min)   (s)
-------------------------------------------------
37.7            360         r'     18.85 +- 0.25
42.3            360         i'     18.5  +- 0.3
-------------------------------------------------

Values have been calibrated against nearby USNOB-1 stars
(R2 and I). Compared with earlier (Buckley et el.)
and later (Kann et al.) observations, our values
suggest an overall power-law decay index ~1.