NUMBER:  3460
SUBJECT: GRB 050509.074: Further I-band imaging
DATE:    05/05/23 12:48:28 GMT

Johan P. U. Fynbo, Brian L. Jensen, Jens Hjorth, Pall Jakobsson, J. M. Castro Cerón, H. Pedersen, Darach Watson (Niels Bohr Institute), Tapio Pursimo, Raine Karjalainen, John Telting (Nordic Optical Telescope), Björn Voss (University of Kiel) report:

"Using StanCAM on the 2.56m Nordic Optical Telescope we have obtained further I-band imaging of the XRT error circle for GRB 050509.074 (Swift trigger 118707, GCN 3379, 3380) on May 19.17. All sources detected in our early i-band images from 20 min and 2.5 hr after the burst (GCN 3389) are also detected in the image from May 19. Our 3-sigma upper limit on the magnitude of any transient source in the XRT error circle (except in the eastern part covered by the bright star) is I=22.5. Images of the field are shown at:

NUMBER:  3389
SUBJECT: GRB 050509A:: Optical observations
DATE:    05/05/09 09:07:30 GMT

J. P. U. Fynbo, B. L. Jensen, J. Hjorth, P. Jakobsson, J. M. Castro Cerón, H. Pedersen, D. Watson (Niels Bohr Institute), J. Näränen (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: