# GAMMA RAYS: OBSERVATIONS

## Casting Light on the Anomalous'' Statistics of Mg II Absorbers Toward Gamma-ray Burst Afterglows: The Incidence of Weak Systems

We revisit echelle spectra (spectral resolution R ≈ 40,000) of eight gamma-ray burst (GRB) afterglows to obtain the incidence (dN/dz) of weak intervening Mg II systems at a mean redshift of langzrang = 1.5. We show that dN/dz of systems having …

## Observations of the Naked-Eye GRB 080319B: Implications of Nature's Brightest Explosion

The first gamma-ray burst (GRB) confirmed to be bright enough to be seen with the naked eye, GRB 080319B at redshift z = 0.937, allowed for exquisite follow-up observations across the electromagnetic spectrum. We present our detailed optical and …

## Temporal Variation in the Abundance of Excited Fe$^+$ Near a Gamma-Ray Burst Afterglow

Excited Si$^+$ and Fe$^+$ species are routinely observed in the host environment of gamma-ray burst (GRB) afterglows but are not commonly seen in other extragalactic locations. Their presence signals unusual properties in the gaseous environment of …

## 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 …

## 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 …