[vsnet-grb-info 17132] GRB 151023A: RATIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18464
SUBJECT: GRB 151023A: RATIR Observations
DATE:    15/10/24 03:59:24 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 (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 151023A (D'Avanzo, et al., GCN 18450) 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 2015/10 24.09 to 2015/10 24.14 UTC (12.35 to 13.66 hours after the BAT trigger), obtaining a total of 1.07 hours exposure in the r, i, and z bands.

We detect the GROND source (Knust, et al., GCN 18461) at a similar brightness level.  In comparison with the USNO-B1 catalog, we find:

   r 20.27 +/- 0.04
   i 19.10 +/- 0.02
   z 18.29 +/- 0.09

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

We note that this source is present in the DSS at a comparable brightness level and may not, therefore, be the GRB afterglow.

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