[vsnet-grb-info 20486] GRB 180402A: RATIR Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22582
SUBJECT: GRB 180402A: RATIR Upper Limits
DATE:    18/04/02 15:51:46 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 180402A (Lien, et al., GCN 22580) 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 2.41 to 2018/04 2.50 UTC (1.8 minutes
to 2.33 hours after the BAT trigger), obtaining a total of 1.76 hours
exposure in the r and i bands.

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

  r > 23.3
  i > 23.3

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

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