[vsnet-grb-info 14026] GRB 131014A: RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15340
SUBJECT: GRB 131014A: RATIR Optical and NIR Observations
DATE:    13/10/15 17:19:59 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja at nasa.gov>

E. Troja (GSFC), Alan M. Watson (UNAM), Nat Butler (ASU),
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),
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 131014A (Fitzpatrick et al., GCN 15332,
Desiante, et al., GCN 15333) 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
2013/10 15.36 to 2013/10 15.52 UTC (27.45 to 31.41 hours after the GBM
trigger), obtaining a total of 2.84 hours exposure in the r and i bands,
1.19 hours exposure in the Z and Y bands, and 1.09 hours exposure in the
J and H bands.

For a source within the Swift-XRT error circle (Kennea et al. GCN 15335),
in comparison with 2MASS, we obtain the following measurements:

   r    23.42 ± 0.21
   i    22.76 ± 0.17
   Z   23.1 ± 0.4 (2.7 sigma)
   Y   21.20 ± 0.27
   J    21.9 ± 0.6 (1.8 sigma)
   H   21.8 ± 0.7 (1.6 sigma)

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The object is located 0.4 arcsec 
from
the NOT afterglow candidate (Schulze et al., GCN 15337) and consistent 
with it.
We cannot determine whether the source is fading. No other uncatalogued
source is detected within the XRT error circle.

Despite the large errors, our preliminary analysis indicates a blue 
continuum in YJH,
suggestive of a possible z-band dropout, and implying a high-redshift (z 
~ 6) for
GRB 131014A.

Further observations are planned.

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