TITLE:   GCN CIRCULAR
NUMBER:  15208
SUBJECT: GRB 130907A: RATIR Optical and NIR Observations
DATE:    13/09/10 05:56:06 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 130907A (Page et al., GCN 15183) 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 10.12 to 2013/09 10.16 UTC (53.18 to
54.12 hours after the BAT trigger), obtaining a total of 0.71 hours
exposure in the r and i bands and 0.30 hours exposure in the Z, Y, J, and H
bands.

For the source reported in Lee et al. (GCN 15192), in comparison with SDSS
DR9 and 2MASS, we obtain the following detections and upper limits
(3-sigma):

  r   21.92 +/- 0.12
  i   21.38 +/- 0.09
  Z   > 21.37
  Y   > 20.87
  J   > 20.58
  H   > 19.97

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  The source has faded by about two
magnitudes in all bands since our measurements two nights ago (Lee et al.,
GCN 15192).  We note that the source intensity in the r and i bands is now
comparable to the cataloged values for the spatially coincident galaxy SDSS
J142333.95+453626.2.

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