[vsnet-grb-info 13676] GRB 130702A: Continued RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14993
SUBJECT: GRB 130702A: Continued RATIR Optical and NIR Observations
DATE:    13/07/07 16:21:05 GMT
FROM:    Nat Butler at Az State U  <natbutler at 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 130702A (Singer et al., GCN 14967; Cheung et
al., GCN 14971; Collazzi & Connaughton, GCN 14972) 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 on the nights of 2013/07/06 and 2013/07/07 (4.25 and 5.26 days
after the BAT trigger), obtaining a total of 1.4 hours exposure in the r'
and i' bands and 0.6 hours exposure in the Z, Y, J, and H bands each night.

At the position of the source from Singer et al. (GCN 14967), in comparison
with SDSS DR9 and 2MASS, we obtain the following detections:

          7/06                        7/07
 r'   19.86 +/- 0.02   19.94 +/- 0.02
 i'   19.89 +/- 0.03   20.02 +/- 0.02
 Z   19.68 +/- 0.05   19.76 +/- 0.04
 Y   19.46 +/- 0.05   19.69 +/- 0.05
 J   19.64 +/- 0.07   19.64 +/- 0.06
 H   19.36 +/- 0.08   19.69 +/- 0.08

The source appears to be slowly fading, approximately 0.1 mag/day, or
approximately as t^-0.35.  This is a significant flattening relative to the
bright fluxes we measured 2 days after the GRB (Butler et al.; GCN 14980).
 These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Further observations are underway.

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