[vsnet-grb-info 18140] GRB 160625B: RATIR Optical and NIR Afterglow Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19588
SUBJECT: GRB 160625B: RATIR Optical and NIR Afterglow Detection
DATE:    16/06/26 08:18:57 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja at nasa.gov>

Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),
Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (GSFC/STScI), Owen Littlejohns (ASU),
Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev
(UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil
Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach
Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of the Fermi LAT GRB 160625B (Dirirsa, et al., GCN 
19580)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico 
Nacional
on Sierra San Pedro Mártir from 2016/06 26.30 to 2016/06 26.32 UTC (8.53
to 9.02 hours after the LAT trigger), obtaining a total of 0.36 hours
exposure in the r and i bands and 0.15 hours exposure in the Z, Y, J
and H bands.

We detect a bright, fading and uncatalogued source at the edge of the 
Swift-XRT
error circle (Melandri, et al., GCN 19585), at a position RA, Dec = 
20:34:23.50,
+6:55:8.1 (J2000, +/-0.5"). In comparison with the USNO-B1 and 2MASS 
catalogs,
we obtain the following values:

   r    = 18.28 +/- 0.01
   i    = 18.08 +/- 0.01
   Z    = 17.95 +/- 0.01
   Y    = 17.78 +/- 0.01
   J    = 17.77 +/- 0.02
   H    = 17.65 +/- 0.02

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

Further observations are on-going.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.