[vsnet-grb-info 18659] GRB 161023A: LCOGT-FTS optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20107
SUBJECT: GRB 161023A: LCOGT-FTS optical observations
DATE:    16/10/24 10:30:23 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), C.G. Mundell 
(U. Bath), A. Gomboc (U. Nova Gorica) on behalf of a large collaboration 
report:

The 2-m LCOGT Faulkes Telescope South began observing INTEGRAL GRB 
161023A (Mereghetti et al., GCN 20103) in the SDSS ri filters on October 
24, 09:17 UT (~0.44 days since the GRB). We clearly detect the optical 
afterglow (Gorbovskoy et al. GCN 20102; Tanvir al. GCN 20104) at the 
position RA(J2000)= 20:44:05.17, DEC(J2000)= -47:39:47.8 (error radius 
of 1 arcsec) with the following values:

Mid time from GRB     Exposure     Filter       Magnitude
(days)                  (s)
-------------------------------------------------------------
0.44                   5x60        SDSS-R       18.57 +- 0.03
0.45                   5x60        SDSS-I       18.38 +- 0.03
-------------------------------------------------------------

Calibration is done against nearby USNOB-1 star 20:44:08.421, 
-47:39:34.63 assuming r=17.27, i=17.20 mag.