TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4981
SUBJECT: GRB 060418: JHKs PAIRITEL Observations of Afterglow
DATE:    06/04/20 00:06:36 GMT
FROM:    Daniel Kocevski at UC Berkeley  <kocevski@berkeley.edu>

Daniel Kocevski, J. S. Bloom (UC Berkeley), and C. H. Blake (Harvard/ 
CfA), on behalf of a larger collaboration, report:

"We began observations of GRB 060417 (Falcone  et. al. GCN 4966) with  
the PAIRITEL 1.3m at 2006-04-18 05:25:34. UTC, 2hr32min after the GRB  
trigger.  The transient reported by Falcone et al. (GCN 4966) is well  
detected in 300s mosaics simultaneously in JHKs bands, and is seen to  
fade between mosaics.  A series of 13 simultaneous JHKs mosaics taken  
over 6 hours of observations shows a power law decline in J with a  
slope of about alpha = 1.11 +/- 0.10 ( F(t)~t^(-alpha) ).  The decay  
slopes measured in H and Ks are consistent with the J band slope  
within error.  This slope is consistent with that reported by  
Nysewander et al. (GCN 4971) and Cobb et al. (GCN 4972).  No break  
was seen in the observed decay out to at least 08:09:31 UTC.

An animated gif of the observations can be found at:
http://lyra.berkeley.edu/~kocevski/GCN/GRB060418.gif


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