[vsnet-grb-info 21091] GRB 180828A: RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23189
SUBJECT: GRB 180828A: RATIR Optical and NIR Observations
DATE:    18/08/29 16:14:03 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), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús
González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:

We observed the field of GRB 180828A (Beardmore, et al., GCN 23182) 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 from 2018/08 29.14 to 2018/08 29.28 UTC (8.29 to
11.70 hours after the BAT trigger), obtaining a total of 1.73 hours
exposure in the r and i bands and 0.79 hours exposure in the Z, Y, J, and H
bands.

We find one uncatalogued source within the Swift-XRT error circle
(Beardmore at at., GCN 23182) at RA, Dec = 17:54:52.5 -25:47:56.3 (J2000,
+/-0.5").  This source is outside the enhanced XRT error region (Evans et
al., GCN 23184), within which we find no new sources.  In comparison with
the 2MASS catalog, we obtain the following detection and 3-sigma upper
limit:

 J > 21.4
 H = 20.8 +/- 0.3

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  We note that this field has high
extinction, with E[B-V]~16.

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