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GCN Circular 14409

GRB 130420A: RATIR Optical and NIR Observations
2013-04-20T11:56:25Z (11 years ago)
Alan M. Watson at Instituto de Astronomia UNAM <>
Alan M. Watson (UNAM), Nat Butler (ASU), 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 observed the field of GRB 130420A (Page, et al., GCN 14406) with the
Reionization and Transients Infrared Camera (RATIR; on the
1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on
Sierra San Pedro M�rtir from 2013/04 20.41 to 2013/04 20.45 UTC (2.48
to 3.38 hours after the BAT trigger), obtaining a total of 0.36 hours
exposure in the r' and i' bands and 0.14 hours exposure in the Z,
Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with SDSS DR8
and 2MASS, we find:

r'	19.81 +/- 0.02
i'	19.41 +/- 0.02
Z	19.37 +/- 0.06
Y	18.99 +/- 0.07
J	19.16 +/- 0.07
H	18.87 +/- 0.11

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

Comparison to the earlier photometry of Morgan et al. (GCN 14408) shows that this source has faded by about 2.5 magnitudes in J and H.

We thank the staff of the Observatorio Astron�mico Nacional in San Pedro 
Dr. Alan M. Watson
Instituto de Astronom�a
Universidad Nacional Aut�noma de M�xico
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