TITLE:   GCN CIRCULAR
NUMBER:  21134
SUBJECT: GRB 170522A: LCO McDonald observations
DATE:    17/05/24 14:52:51 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@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-LAT GRB 170522A (Arimoto et al. GCN 21127; 
Stanbro et al. GCN 21126; Lipunov et al. GCN 21132) on May 23, 03:07 UT 
(11.4 hours since the GRB) with the 1-m LCO unit at the LCO McDonald 
observatory with the SDSS i filter. Within the LAT error circle we do 
not detect any uncatalogued source down to i~19 mag in a 3x120s stacked 
frame, as calibrated against nearby SDSS stars.
Although all of the four X-ray sources reported by Swift-XRT (Mingo et 
al. GCN 21133) lie outside the LAT error circle, three of them (Sources 
1, 2, 3) happen to lie within our field of view. We did not find 
uncatalogued counterparts in any of the corresponding error circles down 
to the same limit.