[vsnet-grb-info 18119] GRB 160623A: RATIR Optical and NIR Observations, Afterglow Confirmation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19567
SUBJECT: GRB 160623A: RATIR Optical and NIR Observations, Afterglow Confirmation
DATE:    16/06/24 16:48:40 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler at gmail.com>

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 (GSFC/STScI),
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), Harvey Moseley (GSFC),
John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 160623A (Vianello, et al., GCN 19553) 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 2016/06 24.44 to 2016/06 24.47 UTC (29.48 to
30.31 hours after the BAT trigger), obtaining a total of 0.56 hours
exposure in the r and i bands and 0.23 hours exposure in the Z, Y, J, and H
bands.

For a source on the edge of the Swift-XRT error circle (Mingo, et al., GCN
19558), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the
following detections:

  r = 21.12 +/- 0.05
  i = 19.77 +/- 0.02
  Z = 18.73 +/- 0.02
  Y = 18.41 +/- 0.02
  J = 17.46 +/- 0.01
  H = 16.93 +/- 0.01

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  Comparing our images to the finder
chart reported by Pozanenko, et al. (GCN 19561), we believe this to be the
same optical source.  It has apparently faded by about 1 mag in r over the
~16 hours separating our observations.

The source is located at RA, Dec = 21:1:11.48, +42:13:14.6 (J2000,
+/-0.5").  Further observations are planned.

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