TITLE:   GCN CIRCULAR
NUMBER:  18028
SUBJECT: GRB 150716A: RATIR Optical Observations
DATE:    15/07/16 17:23:37 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William 
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), 
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara 
(ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico 
Ramirez-Ruiz (UCSC), Jos� A. de Diego (UNAM), Leonid Georgiev (UNAM), 
Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Neil Gehrels (GSFC), 
and Harvey Moseley (GSFC) report:

We observed the field of GRB 150716A (Kocevski et al., GCN 18027) with the 
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 
1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on 
Sierra San Pedro M�rtir from 2015/07 16.30 to 2015/07 16.45 UTC (0.06 to 
3.61 hours after the BAT trigger), obtaining a total of 2.21 hours 
exposure in the r and i bands.

The field is crowded. Nevertheless, we detect a candidate optical 
afterglow within but close to the edge of the unenhanced Swift-XRT error 
circle at 18:33:57.20 -12:58:40.1 (J2000, �0.5"). In comparison with the 
USNO-B1 and 2MASS catalogs, we obtain the following detections:

  r	20.34 � 0.02
  i	19.23 � 0.02

At the moment, we have no information on fading, but further observations 
are
planned.

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astron�mico Nacional in San Pedro
M�rtir.