GCN Circular 21087

A. Cucchiara, D. Morris (U. of Virgin Islands),
C. Guidorzi (U. Ferrara), B. Gendre  (U. of
Virgin Islands), reports on behalf of a larger
collaboration:

"On May 10 at 16:46 UT (T_0 +11.4h) we began observing the center
of the field of LAT GRB 170510A (Bissaldi et al. GCN #21080)
using the Las Cumbres Observatory 1m Sutherland facility.
We covered 50% of the LAT error region and we obtained a series
of 5x120s observations in R band, for a total of 10 minutes on sky.

We identified a possible optical counterpart of GRB170510A located
at the same position of candidate #1 from the Swift-XRT tiled
observations (Evans et al. GCN #21082, Melandri et al. GCN #21086).

Our preliminary photometry for this source is:

R = 19.6 +/- 0.2 mag

At the moment we cannot establish the temporal variability of this source.
This magnitude is calibrated against nearby USNO-B1 sources,
and is not corrected for Galactic Extinction."