COSMOLOGY: OBSERVATIONS

A Jet Model for the Afterglow Emission from GRB 000301C

We present broadband radio observations of the afterglow of GRB 000301C, spanning from 1.4 to 350 GHz for the period of 3-130 days after the burst. These radio data, in addition to measurements in the optical bands, suggest that the afterglow arises …

The Bright Gamma-Ray Burst 991208: Tight Constraints on Afterglow Models from Observations of the Early-Time Radio Evolution

The millimeter wavelength emission from GRB 991208 is the second brightest ever detected, yielding a unique data set. We present here well-sampled spectra and light curves over more than two decades in frequency for a 2 week period. This data set has …

The Rapidly Fading Afterglow from the Gamma-Ray Burst of 1999 May 6

We report on the discovery of the radio afterglow from the gamma-ray burst of 1999 May 6 (GRB 990506) using the Very Large Array. The radio afterglow was detected at early times (Δt=1.5 days) but began to fade rapidly sometime between 1 and 5 days …

The Radio Afterglow from GRB 980519: A Test of the Jet and Circumstellar Models

We present multifrequency radio observations from the afterglow of GRB 980519 beginning 7.2 hr after the gamma-ray burst and ending 63 days later. The fast decline in the optical and X-ray light curves for this burst has been interpreted either as …

The Host Galaxy of GRB 990123

We present deep images of the field of GRB 990123 obtained in a broadband UV/visible bandpass with the Hubble Space Telescope (HST) and deep near-infrared images obtained with the Keck I 10 m telescope. The HST image reveals that the optical …

The Host Galaxy of GRB 990123

We present deep images of the field of GRB 990123 obtained in a broadband UV/visible bandpass with the Hubble Space Telescope (HST) and deep near-infrared images obtained with the Keck I 10 m telescope. The HST image reveals that the optical …

The Host Galaxy of the Gamma-Ray Burst 971214

We report on Hubble Space Telescope (HST) observations of the host galaxy of GRB 971214, taken 4 months after the burst. The redshift of the proposed host galaxy at z=3.418, combined with optical and radio observations of the burst afterglow, implies …

The Host Galaxy of the Gamma-Ray Burst 971214

We report on Hubble Space Telescope (HST) observations of the host galaxy of GRB 971214, taken 4 months after the burst. The redshift of the proposed host galaxy at z=3.418, combined with optical and radio observations of the burst afterglow, implies …

Spectroscopy of the Host Galaxy of the Gamma-Ray Burst 980703

We present spectroscopic observations of the host galaxy of GRB 980703. Several emission and absorption features are detected, making the redshift (z=0.966) completely unambiguous. This is only the third known redshift for a γ-ray burst (GRB) host. …

Spectroscopy of the Host Galaxy of the Gamma-Ray Burst 980703

We present spectroscopic observations of the host galaxy of GRB 980703. Several emission and absorption features are detected, making the redshift (z=0.966) completely unambiguous. This is only the third known redshift for a γ-ray burst (GRB) host. …