[vsnet-grb-info 15674] GRB 141026A: Continued RATIR Optical and NIR Observations, Afterglow Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16962
SUBJECT: GRB 141026A: Continued RATIR Optical and NIR Observations, Afterglow Detection
DATE:    14/10/26 18:50:06 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler at gmail.com>

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
(ORAU/GSFC), 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 141026A (Hagen, et al., GCN 16950)) 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 2014/10 26.13 to 2014/10 26.26 UTC (0.54 to
3.58 hours after the BAT trigger), obtaining a total of 2.49 hours exposure
in the r, i, and z bands.

With increased time-coverage, the source reported in Littlejohns et al.
(GCN 16952; also Perley et al., GCN 16955, Varela et al., GCN 16953,
Gorosabel et al., GCN 16954, ) appears to peak on a timescale of 1 hour,
and then fade in the r and i bands.  Given also that its position is
consistent with the enhanched XRT error region (Beardmore et al., GCN
16956), this source is likely to be the afterglow to GRB 141026A.  In
comparison with 2MASS, we obtain the following detections and upper limit
(3-sigma):

  r     21.74 +/- 0.07
  i     21.54 +/- 0.06
  z  >  20.5

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

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