TITLE:   GCN CIRCULAR
NUMBER:  15165
SUBJECT: GRB 130831A: RATIR Optical and NIR Observations
DATE:    13/09/02 02:52:18 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),
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 130831A (Hagen, et al., GCN 15139) 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 2013/09 1.16 to 2013/09 1.49 UTC (14.65 to
22.73 hours after the BAT trigger), obtaining a total of 5.16 hours
exposure in the r' and i' bands and 2.09 hours exposure in the Z, Y, J, and
H bands.

For a source within the Swift-XRT error circle (Evans et al., GCN 15147),
in comparison with SDSS DR9 and 2MASS, we obtain the following detections:

  r'    20.64 +/- 0.03
  i'    20.38 +/- 0.03
  Z    20.20 +/- 0.07
  Y    19.69 +/- 0.07
  J    19.87 +/- 0.09
  H    19.88 +/- 0.14

These magnitudes are in the AB system and 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.