GCN Circular 18089
Subject
GRB 150727A: RATIR Optical Observations
Date
2015-07-28T16:43:42Z (9 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), 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), 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),
and Harvey Moseley (GSFC) report:
We observed the field of GRB 150727A (Cenko et al., GCN 18076) 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 2015/07 28.15 to 2015/07 28.21 UTC (8.65 to
9.95 hours after the BAT trigger), obtaining a total of 1.07 hours
exposure in the r, i, and z bands.
We detect a source at the edge of the Swift/XRT error circle (Osborne et
al., GCN 18079), at RA, Dec (J2000) = 13:35:52.52, -18:19:31.4 (�0.5"). In
comparison with the USNO-B1 and 2MASS catalogs, we obtain the following
detections and upper limits (3-sigma):
r 21.13 � 0.19
i 21.40 � 0.13
z > 19.57
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
Our detections appear to be consistent with the non-detections at
shallower depths reported by Dichiara et al. (GCN 18083). Tanvir et al.
(GCN 18080) report a tentative spectroscopic redshift of 0.313.
Further observations are planned.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro
M�rtir.