[vsnet-grb-info 16617] GRB 150527A: Continued RATIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17898
SUBJECT: GRB 150527A: Continued RATIR Observations
DATE:    15/06/02 14:25:00 GMT
FROM:    Nat Butler at Az State U  <natbutler at asu.edu>

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), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús
González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and
Harvey Moseley (GSFC) report:

We observed the field of GRB 150527A (Evans, et al., GCN 17874) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on
Sierra San Pedro Mártir initially from 2015/05 27.29 to 2015/05 27.45 UTC
(0.17 to 4.06 hours after the BAT trigger), obtaining a total of 3.10 hours
exposure in the r, i, and z bands and then again from 2015/05 28.25 to
2015/05 28.47 UTC (23.27 to 28.36 hours after the BAT trigger), obtaining a
total of 3.91 hours exposure in the r, i, and z bands.

The source we initially detected (Butler, et al., GCN 17876; RA, Dec =
19:15:50.27, 4:12:4.7; J2000, +/-0.5") in the Swift-XRT error circle
(Evans, et al., GCN 17874) has not faded in our extended dataset and is,
therefore, unlikely to be the afterglow.

We note the REM source (Nicastro, et al., GCN 17881) is marginally detected
in our first epoch observation with i=23.4 +/- 0.5, calibrated relative to
the USNO-B1 catalog.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.