[vsnet-grb-info 17727] GRB 160310A: RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19166
SUBJECT: GRB 160310A: RATIR Optical and NIR Observations
DATE:    16/03/11 14:05:14 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja at nasa.gov>

Eleonora Troja (GSFC), 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), 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 the Fermi GRB 160310A (Vianello, et al., GCN 
19158; Toelge, et al., GCN 19161) 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 2016/03 11.16 to 2016/03 11.32 UTC (27.46 to 31.25 hours 
after the GBM trigger).

We observed the two uncatalogued X-ray sources detected by the Swift/XRT 
(Gibson, et al., 19162). For source #1 we obtained a total of 1.07 hours 
exposure in the r and i bands and 0.45 hours exposure in the J, and H 
bands. For a source within the XRT error circle, in comparison with the 
USNO-B1 and 2MASS catalogs, we obtain the following detections:

   r    19.89 ± 0.02
   i    19.34 ± 0.01
   J    18.03 ± 0.01
   H    17.37 ± 0.01

These values are consistent with the magnitudes of a USNO-B1 catalogued 
object. No other source is visible within the XRT localization.

For source#2 we obtained a total of 1.78 hours exposure in the r and i 
bands and 0.75 hours exposure in the J, and H bands. For a source within 
the XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, 
we obtain the following detections:

   r    22.48 ± 0.09
   i    21.82 ± 0.05
   J    20.62 ± 0.10
   H    20.03 ± 0.08

These magnitudes are in the AB system and are not corrected for Galactic 
extinction in the direction of the GRB. Our values are slightly fainter 
than the NOT detection (Kruehler, et al., GCN 19164), although no strong 
claim about variability can be made at this time. Further observations 
to determine the nature of source #2 are encouraged.

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