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GCN Circular 18072

GRB 150724B: RATIR Optical Observations
2015-07-27T03:33:50Z (9 years ago)
Alan M. Watson at Instituto de Astronomia UNAM <>
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 LAT GRB 150724B (Bissaldi et al., GCN 18065) 
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 2015/07 26.28 to 
2015/07 26.48 UTC (36.02 to 40.86 hours after the BAT trigger), obtaining 
a total of 2.39 hours exposure in the r and i bands.

For a source within the Swift XRT error circle (Osborne et al., GCN 
18069), in comparison with the SDSS DR9 catalog, we obtain the following 

   r	23.24 +/- 0.34
   i	22.39 +/- 0.15

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

At this moment we have no information on fading. Further observations are 

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