Of the cosmological gamma-ray bursts, GRB 011121 has the lowest redshift, z=0.36. More importantly, the multicolor excess in the afterglow detected in the Hubble Space Telescope (HST) light curves is compelling observational evidence of an underlying …
We present millimeter- and submillimeter-wavelength observations and near-infrared K-band imaging toward the bright gamma-ray burst GRB 010222. Over seven different epochs, a constant source was detected with an average flux density of 3.74+/-0.53 …
GRB 970828 was the first well-localized γ-ray burst (GRB) X-ray afterglow for which no optical afterglow was found despite a prompt, deep search down to R$_lim$åisebox-0.5ex 24.5 mag. We report the discovery of a short-lived radio flare within the …
We present a comprehensive sample of all gamma-ray burst (GRB) afterglows with known distances, and we derive their conical opening angles based on observed broadband breaks in their light curves. Within the framework of this conical jet model, we …
GRB 000926 has one of the best-studied afterglows to date, with multiple X-ray observations, as well as extensive multifrequency optical and radio coverage. Broadband afterglow observations, spanning from X-ray to radio frequencies, provide a probe …
We report on optical, near-infrared, and centimeter radio observations of GRB 000418 that allow us to follow the evolution of the afterglow from 2 to 200 days after the γ-ray burst (GRB). In modeling these broadband data, we find that an isotropic …
The gamma-ray burst of 1997 February 28 (GRB 970228) ushered in the discovery of the afterglow phenomenon. Despite intense study of the nearby galaxy, however, the nature of this galaxy and the distance to the burst eluded the community. Here we …
We present multicolor light curves of the optical afterglow of gamma-ray burst (GRB) 000926. Beginning åisebox-0.5ex 1.5 days after the burst, the light curves of this GRB steepen measurably. The existence of such achromatic breaks is usually taken …
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 optical light curve of the energetic γ-ray burst GRB 991216 is consistent with jetlike behavior in which a power- law decay steepens from t$^-1.22+/-0.04$ at early times to t$^-1.53+/-0.05$ in a gradual transition at around 2 days. The derivation …