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GCN Circular 15436

GRB 131030A: Continued RATIR Optical and NIR Observations
2013-11-01T19:26:33Z (11 years ago)
Owen Littlejohns at Az State U <>
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), Jos� A. de
Diego (UNAM), Leonid Georgiev (UNAM), Jes�s Gonz�lez (UNAM),
Carlos Rom�n-Z��iga (UNAM), Neil Gehrels (GSFC), and Harvey
Moseley (GSFC) report:

We again observed the field of GRB 131030A (Troja, et al., GCN 15402) with
the Reionization and Transients Infrared Camera (RATIR; on
the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional
on Sierra San Pedro M�rtir from 2013/11 1.08 to 2013/11 1.20 UTC (29.01 to
31.91 hours after the BAT trigger), obtaining a total of 2.13 hours exposure
in the r and i bands and 0.88 hours exposure in the Z, Y, J, and H bands.

We continue to detect the uncatalogued source reported by UVOT (Troja et
al., GCN Circ. 15414), at fainter magnitudes than the first epoch of RATIR
observations (Littlejohns et al., GCN Circ. 15420). In comparison with the
SDSS DR9 and 2MASS, we obtain the following detections:

  r     20.73 +/- 0.03
  i     20.45 +/- 0.03
  Z     20.19 +/- 0.05
  Y     20.06 +/- 0.07
  J     20.07 +/- 0.08
  H     19.57 +/- 0.11

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. In comparison with the first epoch
RATIR observations these magnitudes can be modelled with power-law
decays, with indices of approximately t^-1.1 for the r and i bands, t^-1.0
the Z, Y and J bands and t^-0.8 for the H band.

We thank the staff of the Observatorio Astron�mico Nacional in San Pedro
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