GCN Circular 4970
Subject
GRB 060418, SMARTS optical/IR afterglow observations
Event
Date
2006-04-18T05:05:45Z (20 years ago)
From
Bethany Cobb at Yale U <cobb@astro.yale.edu>
B. E. Cobb (Yale), part of the larger SMARTS
consortium, reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 060418
(Falcone et al. GCN 4966) beginning ~1 hours post-burst
(2006-04-18 04:05 UT). Several dithered images
were obtained in each filter, with total summed exposure times
of 180s in each of BRIYJK and 120s in each of H and V.
The afterglow candidate reported by Falcone et al. and
confirmed by Covino et al. (GCN 4967) and Melandri et al. (GCN 4968)
is visible in all wavebands, from B to K. At a mid-exposure
time of 1.2 hrs post-burst, the preliminary K-band magnitude
of the afterglow candidate is K = 14.1 +/- 0.1. This value is obtained
by comparison with nearby 2MASS standards. The lack of a Lyman-alpha
forest absorption break suggest this GRB has a redshift of z<~3.