Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 3389

GRB 050509A: Optical observations
2005-05-09T09:07:30Z (19 years ago)
Johan U. Fynbo at U.Copenhagen <>
GRB 050509A: Optical observations

J. P. U. Fynbo, B. L. Jensen, J. Hjorth, P. Jakobsson, 
J. M. Castro Cer�n, H. Pedersen, D. Watson (Niels Bohr Institute),
J. N�r�nen (Nordic Optical Telescope) report:

"Using ALFOSC on the 2.56m Nordic Optical Telescope we have obtained 
I-band imaging of the XRT error circle for GRB 050509A (Swift trigger
118707, GCN 3379, 3380) at two epochs starting ~20 min and ~2.5 hr 
after the GRB trigger. In the XRT error-circle we detect several
sources. One source is less than 2" from the centre of the XRT error 
circle and not seen in the DSS-II (red). The position of this source is:

RA(2000) = 20:42:19.60,  Dec(2000) = +54:04:17.8

The source is fainter than the sensitivity of the DSS-II red image and 
has an estimated magnitude of I = 21.7 (not corrected for a galactic 
extinction of A_I = 1.15 mag). The source does not vary significantly 
between the two epochs. An image of the field is shown at:
Looking for U.S. government information and services? Visit