Astrophysics

A Search for Optical Afterglow from GRB 970828

We report on the results of R-band observations of the error box of the γ-ray burst of 1997 August 28 made between 4 hr and 8 days after this burst occurred. No counterpart was found varying by more than 0.2 mag down to R=23.8. We discuss the …

Using STIS to find gamma-ray burst redshifts

A recent spectrum of the optical afterglow of GRB 970508 suggests that gamma-ray bursts (GRBs) are cosmological in origin, and it is of crucial importance to derive an accurate distance to each burst. If GRBs occur near their host galaxies …

Testing for Extragalactic Correlations of Gamma-Ray Bursts

If gamma-ray bursts (GRBs) are cosmological they need not necessarily be spatially coincident with a host galaxy--in many cosmological models the progenitors are ejected to large distances from their parent galaxies. While the optical transient of …

The decay of optical emission from the γ-ray burst GRB 970228.

The optical counterpart of the γ-ray burst GRB 970228 appears to be a transient point source embedded in a region of extended nebulosity, the latter having been tentatively identified as a high-redshift galaxy. This would seem to favour models that …

The decay of optical emission from the γ-ray burst GRB 970228.

The optical counterpart of the γ-ray burst GRB 970228 appears to be a transient point source embedded in a region of extended nebulosity, the latter having been tentatively identified as a high-redshift galaxy. This would seem to favour models that …

The corrected log N-log fluence distribution of cosmological γ-ray bursts

Recent analysis of relativistically expanding shells of cosmological γ-ray bursts has shown that if the bursts are cosmological, then most likely total energy (E$_0$) is standard and not peak luminosity (L$_0$). Assuming a flat Friedmann cosmology …

Determination of Distance from Time Dilation of Cosmological Gamma-Ray Bursts

The isotropic distribution of gamma-ray bursts (GRBs) as observed with the Burst and Transient Source Experiment (BATSE) strongly suggests that the bursts are at cosmological distances. At such distances, the expansion of the universe should redshift …