TITLE:   GCN CIRCULAR
NUMBER:  15262
SUBJECT: GRB 130925A: Continued RATIR Optical and NIR Observations
DATE:    13/09/26 17:50:25 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), 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 (UCSC),
Eleonora Troja (GSFC), 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), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130925A (Lien, et al., GCN 15246) 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 2013/09 26.28 to 2013/09 26.51 UTC (26.43 to
31.98 hours after the BAT trigger), obtaining a total of 3.66 hours
exposure in the r and i bands and 1.12 hours exposure in the Z, Y, J, and H
bands.

For the uncatalogued source in the enhanced Swift-XRT error circle (Evans
et al., GCN 15251) reported previously (Butler et al., GCN 15258), in
comparison with 2MASS, we obtain the following detections and upper limit
(3-sigma):

 r      22.29 +/- 0.16
 i      21.36 +/- 0.13
 Z      > 21.5
 Y      21.28 +/- 0.29
 J      19.69 +/- 0.06
 H      20.02 +/- 0.17

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  Compared to our observations the
night before (GCN 15258), the source has apparently remained approximately
constant in flux in all bands.   We cannot determine, as did Sudilovsky et
al. (GCN 15247), that the source is fading.


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