TITLE:   GCN CIRCULAR
NUMBER:  25977
SUBJECT: GRB 191004B: Continued Optical Afterglow Monitoring with LCO
DATE:    19/10/07 20:11:14 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We obtained a second epoch (first epoch, GCN 25949) of Swift GRB 191004B (Palmer et al., GCN 25947) data with
the LCO 1-m Sinistro instrument at the Sutherland Site (SAAO) on September 5, from 2:40 to 3:03 UT
(corresponding to 4.95 to 5.3 hours from the GRB trigger time)
with the Bessel R and I filters.

We performed a series of 5x240s exposures, and we detect the afterglow with the following magnitudes:

R = 21.01 +/- 0.08
I = 19.91 +/- 0.08

This flux is calibrated against several USNO-B1.0 objects near the GRB location but is not corrected for Galactic Extinction.

These observations were possible thanks to the USVI NASA-EPSCoR
Research Infrastructure Development (RID) grant NNX16AL44A.