GCN Circular 17762

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
(ORAU/GSFC), 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 the short-duration GRB 150424A (Beardmore, et al.,
GCN 17743
Not 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 2015/04 25.14 to 2015/04
25.28 UTC (19.54 to 23.05 hours after the BAT trigger), obtaining a total
of 2.4 hours exposure in the r, i, and z bands.

The optical afterglow (Perley, GCN 17745
Not found
 
 
; Marshall & Beardmore, GCN 17751
Not found
 
 
;
Malesani, et al., GCN 17756
Not found
 
 
; Kann, et al., GCN 17757
Not found
 
 
) is well-detected.  In
comparison with 2MASS and the USNO-B1 catalog, we obtain the following
detections and upper limit (3-sigma):

  r     21.92 +/- 0.11
  i     21.65 +/- 0.09
  z     > 20.17

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  Compared to the earlier NOT and
GROND observations, the source appears to be continuing its strong fade
(Kann, et al. GCN 17757
Not found
 
 
).

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