GCN Circular 2168
Subject
Optical Observations of GRB 030418 with Magellan
Event
Date
2003-04-25T01:11:43Z (23 years ago)
From
George Ricker at MIT <grr@space.mit.edu>
Optical Observations of GRB 030418 with Magellan
A. Dullighan, N. R. Butler, G. R. Ricker, J. L. Elliot, K. Clancy
(MIT), and D. Osip (Las Campanas Observatory)
report:
On 2003 April 21.01 UT, we observed the optical afterglow (Price et
al; GCN2148) of the HETE-localized GRB 030418 (=H2686) with the
Magellan 6.5 meter Clay telescope at Las Campanas Observatory in
Chile. Our observations consisted of three 300s R-Band images and
one 300s I-Band image, taken with the MagIC instrument. The
afterglow brightness had declined significantly since the
measurement reported in GCN2148, consistent with a power law decay
index = 1.3+/-0.1. The afterglow was still point-like in our images,
with a FWHM of 0.5 arcsec. Our results were as follows:
UT t-t0 (days) Mag
2003-04-21.02 2.60 R=23.64 +/- 0.07
2003-04-21.03 2.61 I=22.60 +/- 0.05
The magnitudes reported above are relative to those of the USNO B1
catalog star at RA = 10h 54m 32.71s, Dec = -07:02:16.4 (J2000), taken
as having R=19.33 and I=18.31. Magnitude errors for the USNO star
were not available, and so are not included in the errors we report
here. Possible errors in the magnitudes of the USNO catalog star
should be taken into account when comparing our afterglow magnitudes
to other measurements. Further observations are planned.
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