[vsnet-grb-info 14736] GRB 140331A: RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16050
SUBJECT: GRB 140331A: RATIR Optical and NIR Observations
DATE:    14/03/31 08:45:28 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 observed the field of GRB 140331A (Zhang, et al., GCN 16049) 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 2014/03 31.26 to 2014/03
31.32 UTC (0.35 to 1.87 hours after the BAT trigger), obtaining a total of
1.04 hours exposure in the r and i bands and 0.44 hours exposure in the
Z, Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with
the SDSS DR9 and 2MASS, we obtain the following detections:

  r     22.02 +/- 0.11
  i     20.79 +/- 0.04
  Z     20.14 +/- 0.06
  Y     19.81 +/- 0.07
  J     19.75 +/- 0.08
  H     19.76 +/- 0.12

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. This position coincides with a
previously detected source, SDSS J085927.51+024304.0. We note that our
r, i and Z band magnitudes are broadly consistent with those of the SDSS.

Fitting Milky Way, LMC and SMC extinction laws in addition to the IGM
(see Littlejohns, et al. 2014) we find the source is possibly of high
redshift, with a photometric redshift of z = 4.65 (+0.34,-2.80; 90% conf.).
The large lower limit in the confidence region is due to a potential
solution
with a high quantity of Milky Way type dust.

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