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GCN Circular 14404

Subject

GRB 130418A: Continued RATIR Optical and NIR Observations

Date

2013-04-20T07:11:53Z (11 years ago)

From

Nat Butler at Az State U <natbutler@asu.edu>

Subject: Subject: GRB 130418A: Continued RATIR Optical and NIR Observations

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
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), and Harvey Moseley (GSFC)
report:

We re-observed the field of GRB 130418A (De Pasquale, et al., GCN 14377Not found
 
 
)
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 2013/04 20.14 to 2013/04 20.26 UTC
(32.30 to 35.30 hours after the BAT trigger), obtaining a total of 2.13
hours exposure in the r' and i' bands and 0.89 hours exposure in the Z, Y,
J, and H bands.

Relative to our observations last night (GCN 14388Not found
 
 
), the GRB afterglow has
faded significantly, by approximately 3 magnitudes in all bands.  In
comparison with SDSS DR8 and 2MASS, we find:

  r'    21.74 +/- 0.12
  i'    21.80 +/- 0.16
  Z     21.52 +/- 0.26
  Y     21.01 +/- 0.21
  J     20.65 +/- 0.17
  H     20.98 +/- 0.35

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Uncertainties are 1-sigma.

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