[vsnet-grb-info 1970] GRB050814: Fading red source

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3809
SUBJECT: GRB050814: Fading red source
DATE:    05/08/15 08:36:17 GMT
FROM:    Brian Lindgren Jensen at U.of Copenhagen  <brian_j at astro.ku.dk>

Brian L. Jensen, Johan P. U. Fynbo, Jens Hjorth, Jesper Sollerman,
José María Castro Cerón, Kristian Pedersen, Páll Jakobsson,
Darach Watson (DARK, NBI), Jan-Erik Solheim (U. of Olso, Norway)
report:

"Using ALFOSC on the Nordic Optical Telescope we have obtained VRI
imaging of the field of GRB 050814.485 (Retter et al., GCN#3799)
on August 15.1, 2005 UT (~13.5 h after the burst).
In the refined XRT error-circle (Morris et al., GCN#3805) we clearly
detect the source reported by Bradly Cenko (GCN#3807) in our I- and
R-band images, whereas the source is absent in the V-band.

Based on preliminary photometry, we obtain for the source :

Date (UT)   Filter  Exptime Seeing  Mag
Aug 15.04   V       3x300s  1.1"    >23.0
Aug 15.06   R       3x300s  1.0"    23.2
Aug 15.07   I       3x300s  0.9"    20.5

Compared to the preliminary I-band detection reported in GCN#3807, the
source appears to be fading.
The colours of the object, if it is the afterglow of GRB 050814.485,
indicate either a high redshift (4.5<z<6.5) or significant
dust-reddening.

In addition, we detect a fainter, bluer source on the edge of the XRT
error-circle (at (RA,Dec)(J2000.0) = 17:36:44.93, +46:20:22.33).

An image of the field is shown at:

http://www.astro.ku.dk/~brian_j/grb/grb050814.485/ "