Ground-based gamma-ray burst follow-up efforts: Results of the first two years of the BATSE/COMPTEL/NMSU Rapid Response Network

In this paper we describe the capabilities of the BATSE/COMPTEL/NMSU Rapid Response Network and report on results obtained during its first 2 years of operation. This network is a worldwide association of 22 radio and optical observatories that perform follow-up searches of newly discovered gamma-ray burst error boxes by the Compton Gamma Ray Observatory. During the last 2 years, it has deeply imaged 10 gamma-ray error boxes over time frames from a few hours to a month after burst detection, and it finds no sources that can be associated unambiguously with a gamma-ray burst. We suggest that significant optical or radio emission is not produced by gamma-ray bursts more than a day after the burst. This result is consistent with recent theoretical models by Katz, Mészâros, Rees, & Papathanassiou, and Paczyński & Rhoads; however, our hours to days optical response time and radio sensitivity limits allow only a weak constraint to be placed on these models. Based upon this study and other published works, we suggest that future work should concentrate on acquiring deep optical images (m ≥ 12) of small gamma-ray error boxes well within a day of the burst. Ideally, radio observations should begin as soon after the burst as possible, reach a sensitivity of ≤1 mJy, and be continued with occasional images being acquired for at least a month following burst detection.