[vsnet-grb-info 16130] GRB 150204A: LCOGT-Sutherland and Siding Springs observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17412
SUBJECT: GRB 150204A: LCOGT-Sutherland and Siding Springs observations
DATE:    15/02/05 19:37:30 GMT
FROM:    Simone Dichiara at Ferrara U/Italy  <dichiara at fe.infn.it>

S. Dichiara, C. Guidorzi (U. Ferrara), D. Kopac,
A. Gomboc (U. Ljubljana), C.G. Mundell (LJMU),
on behalf of a large collaboration report:

Two of the Las Cumbres Observatory 1-m telescopes in Sutherland
(South Africa) began observing simultaneously Swift and Fermi
GRB 150204A (Cummings et al. GCN 17404; Burns & Yu GCN 17408)
on February 04 at 19:47:41 UT, i.e. ~13.3 hours after the GRB,
with the r' and i' filters.
We re-observed with two 1-m telescopes in Siding Springs
(Australia) starting on February 05 at 13:58:33 (~31.4 hours)
with the same filters.

Within the XRT error circle (Melandri et al. GCN 17409)
we found no new source down to the following limit:

Mid time from  Total Exp   Filter    Magnitude
trigger (hr)   (s)
-------------------------------------------------
13.37          120x10      r'         > 19.6
13.56          120x10      i'         > 18.6
-------------------------------------------------

We found two uncatalogued sources close to the XRT error circle
at RA=10:40:55.98 Dec=-64:02:26.01 and RA=10:40:56.51 Dec=-64:02:13.8 (J2000)
with magnitudes r=19.68 +- 0.13 i=18.32 +- 0.13, r=19.47 +- 0.12
i=18.23 +- 0.12, respectively. However, image subtraction revealed
no significant variation between the two epochs.
The same conclusion holds for the entire BAT error circle
(Stamatikos et al. GCN 17406).
Magnitudes are calibrated against nearby USNO-B1 R2 and I
values.