[vsnet-grb-info 20535] GRB 180410A: RATIR Optical Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22631
SUBJECT: GRB 180410A: RATIR Optical Observations 
DATE:    18/04/11 16:03:38 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan at astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), 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 180410A (Gropp et al., GCN 22620) 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 2018/04 11.13 to 2018/04 11.25 UTC (19.10
to 21.87 hours after the BAT trigger), obtaining a total of 2.13 hours
exposure in the r and i bands.

For a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following upper limits (3-sigma):

 r	> 24.20
 i	> 23.90

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

The XRT error region is only 2.8 arcsec from a previously cataloged star with r = 18.1 and i = 17.4. Thus, our formal upper limits given above may be optimistic.

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