[vsnet-grb-info 3909] GRB 061019: SMARTS afterglow confirmation
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Fri Oct 20 01:25:56 JST 2006
TITLE: GCN CIRCULAR
NUMBER: 5734
SUBJECT: GRB 061019: SMARTS afterglow confirmation
DATE: 06/10/19 16:25:49 GMT
FROM: Bethany Cobb at Yale U <cobb at 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 061019
(GCN 5728, Guidorzi et al.) with a mid-exposure time of
2006-10-19 07:29 UT, which is ~3.2 hours post-burst.
Total summed exposure times amounted to 15 minutes in I and V and
12 minutes in J and K.
Within the error region of the X-ray afterglow detection
(GCN 5729, Guidorzi et al.), we detect the source reported
by Covino et al. (GCN 5730), in the I, J and K bands.
The source is not detected in V, to a limiting magnitude
of ~22. The preliminary magnitudes of this source
(calibrated against several 2MASS stars in IR and USNO-B1.0
stars in the optical) are:
time post-
burst (hrs) I J K
------------------------------------------------------------
3.2 20.2 +/- 0.3 17.9 +/- 0.1 15.4 +/- 0.1
(not corrected for the expected high Galactic extinction)
This indicates that the source has faded by ~1 magnitude
since the Covino et al. K-band observations, taken
~1.1 hours post-burst. This source is therefore confirmed to
be the afterglow of GRB 061019, wth a decay rate of alpha ~ -0.8.
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