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GCN Circular 18512

Subject
GRB 151027B: RATIR Observations
Date
2015-10-28T14:10:19Z (9 years ago)
From
Nat Butler at UC berkeley <natxbutler@gmail.com>
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), 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), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 151027B (Ukwatta et al., GCN 18499Not found
 
 
) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2015/10 28.26 to 2015/10 28.51 UTC (7.46 to 13.55 hours after the BAT trigger), obtaining a total of 3.51 hours exposure in the r, i, and z bands.

We detect a source at 05:04:52.69 -06:27:00.8 (J2000, +/-0.05), within the Swift-XRT error circle. In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections:

   r =  20.83 +/- 0.05
   i =  20.18 +/- 0.04
   z =  19.49 +/- 0.21

These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.

This source coincides with the source reported by Malesani et al. (GCN 18501Not found
 
 
), Xu et al. (GCN 18505Not found
 
 
), Wiseman et al. (GCN 18507Not found
 
 
), and Buckley et al. (GCN 18511Not found
 
 
). The source appears to have faded since these earlier observations and furthermore fades by about 0.5 mag in i over the course of our observations.

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