Prompt Optical Emission from Gamma-ray Bursts
astro-ph
/ Authors
Robert Kehoe, Carl Akerlof, Richard Balsano, Scott Barthelmy, Jeff Bloch, Paul Butterworth, Don Casperson, Tom Cline, Sandra Fletcher, Fillippo Frontera
and 12 more authors
Galen Gisler, John Heise, Jack Hills, Kevin Hurley, Brian Lee, Stuart Marshall, Tim McKay, Andrew Pawl, Luigi Piro, Bill Priedhorsky, John Szymanski, Jim Wren
/ Abstract
The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure contemporaneous and early afterglow optical emission from gamma-ray bursts (GRBs). The ROTSE-I telescope array has been fully automated and responding to burst alerts from the GRB Coordinates Network since March 1998, taking prompt optical data for 30 bursts in its first year. We will briefly review observations of GRB990123 which revealed the first detection of an optical burst occurring during the gamma-ray emission, reaching 9th magnitude at its peak. In addition, we present here preliminary optical results for seven other gamma-ray bursts. No other optical counterparts were seen in this analysis, and the best limiting sensitivities are m(V) > 13.0 at 14.7 seconds after the gamma-ray rise, and m(V) > 16.4 at 62 minutes. These are the most stringent limits obtained for GRB optical counterpart brightness in the first hour after the burst. This analysis suggests that there is not a strong correlation between optical flux and gamma-ray emission.