[vsnet-grb-info 15682] GRB 141026A: Continued RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16970
SUBJECT: GRB 141026A: Continued RATIR Optical and NIR Observations
DATE:    14/10/28 17:48:18 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej at asu.edu>

Owen Littlejohns (ASU), 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), 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 again 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 28.13 to 2014/10
28.19 UTC (48.58 to 49.84 hours after the BAT trigger), obtaining a
total of 1.07 hours exposure in the r, i and z bands.

For a source within the Swift-XRT error circle, we obtain the
following upper limits (3-sigma):

  r     > 23.54
  i     > 23.31
  z     > 19.82

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. In comparison to previous epochs
of RATIR observations (Butler, et al., GCN 16965; Littlejohns, et al.,
GCN 16962), the GRB has continued to fade. The r band upper limit
indicates a power-law decay between this and the previous epoch of RATIR
observations with a minimum approximate index of t^(-0.9). This is
steeper than that reported in Butler, et al. (GCN 16965).

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