GCN Circular 3425
Subject
XRF 050509c optical afterglow
Date
2005-05-16T10:55:28Z (19 years ago)
From
Jens Hjorth at U.Copenhagen <jens@astro.ku.dk>
J. Gorosabel (IAA-CSIC), B. L. Jensen (NBI), G. Galaz (Pont. Uni. de Chile),
R. Salinas (Uni. de Concepcion), J. Hjorth, J. P. U. Fynbo, H. Pedersen,
D. Watson, P. Jakobsson, J. M. Castro Cer�n (NBI), report:
"We have carried out R-band observations of XRF 050509c (HETE trigger #3751;
GCN 3402) error box with the 1.54m Danish telescope (+DFOSC) on La Silla,
as follows:
======================================
Date UT t-to Texp Seeing
May 2005 (hr) (s) (")
--------------------------------------
10.1545-10.1703 5.1 2x600 1.2
14.0490-14.0829 98.8 4x600 1.3
======================================
Both observations are centred in the SXC error box covering ~80% of it.
Comparison of the two epoch images reveals, well centred in the SXC error
box, a fading point-like object with coordinates:
RA(J2000) = 12:52:53.94
Dec(J2000) = -44:50:04.1 (internal astrometric error of 1")
which we propose as the XRF 050509c optical afterglow.
Assuming R = 17.9 for the USNO star placed at (12:52:52.34, -44:49:23.1)
we estimate a decay from R~20.1 to R~24.0 between the two epochs. This
would imply a power-law decay index of -1.2 typical of GRB afterglows.
Finding charts can be found at:
http://www.dsri.dk/~jgu/grb050509c/FCs/grb050509c.1.54dk.epoch1.gif
http://www.dsri.dk/~jgu/grb050509c/FCs/grb050509c.1.54dk.epoch2.gif
Further observations are planned."