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GCN Circular 18543

GRB 151027B: RATIR Late-Time Upper Limits
2015-10-31T15:12:21Z (9 years ago)
Nat Butler at UC berkeley <>
Nat Butler (ASU), Alan M. Watson (UNAM), 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 18499) 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 2015/10 31.23 to 2015/10 31.52 UTC (78.85 to 85.85 hours after the BAT trigger), obtaining a total of 5.20 hours exposure in the r, i, and z bands.

We no longer detect the optical afterglow (Malesani et al., GCN 18501).  In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

   r > 23.45
   i > 23.39
   z > 18.57

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

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