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GCN Circular 19243

GRB 160327A: Continued RATIR Optical and NIR Observations
2016-03-28T20:27:50Z (8 years ago)
V. Zach Golkhou at ASU/RATIR <>
V. Zach Golkhou (ASU), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander
Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox
(STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(GSFC/STScI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), 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), Harvey
Moseley (GSFC), John Capone (UMD), and Vicki Toy (UMD) report:

We observed the field of GRB 160327A (Racusin, et al., GCN 19235) 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 2016/03 28.14 to 2016/03 28.39 UTC (17.98 to
24.15 hours after the BAT trigger), obtaining a total of 4.21 hours
exposure in the r and i bands and 1.76 hours exposure in the Z, Y, J, and H

For a source within the Swift-XRT error circle (Goad, et al., GCN 19237),
in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following

  r	23.84 +/- 0.22
  i	23.29 +/- 0.14
  Z	22.57 +/- 0.20
  Y	22.83 +/- 0.35
  J	22.43 +/- 0.29
  H	21.75 +/- 0.23

These magnitudes are in the AB system and are not corrected for
Galactic extinction
in the direction of the GRB. Compared to our previous night of observations
(Golkhou et al., GCN 19236), the source flux has decayed substantially in
all bands. The source r - i color changes from 2.1 +/- 0.1 to 0.6 +/-
0.3 between our first and the second night observations. The strong color
change suggests the possibility of contamination by the GRB host galaxy at

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