[vsnet-grb-info 19395] GRB 170510A: LCO Siding Springs early observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21110
SUBJECT: GRB 170510A: LCO Siding Springs early observations
DATE:    17/05/19 13:47:40 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

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

We began observing Fermi GRB 170510A (Bissaldi et al. GCN 21081) on May 
10, 12:14 UT (7.0 hours since the GRB) with a 1-m LCO unit with the SDSS 
i filter.  Within the Swift-XRT error circle (Cholden-Brown et al. GCN 
21103) we clearly detect the optical afterglow candidate (Cucchiara et 
al. GCN 21087; Lipunov et al. GCN 21091) at the following position:

RA(J2000) =  10:40:36.89
DEC(J2000)= -39:12:45.2

with an error radius of 1.0", with the following value:

Mid Time     Exposure       Filter       Magnitude (AB)
(hours)        (s)
-------------------------------------------------------
7.1           5x120         SDSS-I        18.60 +- 0.07
-------------------------------------------------------

as calibrated against nearby UCAC4 stars.