Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 2594

GRB 040511: Second Epoch Optical Observations
2004-05-13T06:30:49Z (20 years ago)
Josh Bloom at Harvard/CFA <>
GRB 040511: Second Epoch Optical Observations

Nidia Morrell (Las Campanas Observatory), Hsiao-Wen Chen (MIT), Joshua S.
Bloom (Harvard/CfA), Jason X. Prochaska (UCO/Lick), A. Dullighan, G.
Ricker, N. Butler, and R. Vanderspek (MIT):

"We have obtained a second epoch of R-band images of the field around GRB
040511 (Dullinghan et al., GCN #2588) using the SITe#3 CCD imager on the
40 inch Swope telescope at the Las Campanas Observatory.  The observations
were carried out starting at 01:30 UT 13 May 2004 (~36 hours after the
burst).  Three exposures of 600 sec duration were taken under photometric
and sub-arcsec seeing conditions.  The 5-sigma depth of the stacked image
is R~23.6 mag over a 2"-diameter aperture.

A comparison of the stacked image with the first-epoch images obtained at
~11 hr after the burst (Chen et al., GCN #2591) shows that none of the
~7100 sources of Rc <~ 23 in the 14.8' x 20' region have variability by
more than 0.25 mag. The few larger-amplitude outliers in the magnitude
(epoch1) vs. magnitude (epoch2) plot are due to detector artifacts."

The magnitude-magnitude plot that shows the comparison of object
photometry obtained from two epochs and all the imaging data are publicly
available at Click the "Data" link.

This message may be cited.
Looking for U.S. government information and services? Visit