Program: GS-2009A-Q-23

The Swift satellite has revolutionized the study of GRBs by providing unprecedented numbers of accurate real-time localizations. With rapid and automated access to GMOS-S, Gemini has emerged as the cornerstone facility of our group's GRB research efforts. This year, Swift has been joined in orbit by the Fermi Gamma-Ray Telescope with its GeV-photon sensitive LAT detector, which has already detected emission from several events. We aim to measure the redshifts of Fermi bursts so that the detection of ultra-high-energy GRB photons may be used for derivative science such as measuring GRB Lorentz factors and constraining theories of quantum gravity. We also seek to differentiate between high reddening and redshift when GRBs have suppressed optical afterglows. Constraining the number of "dark" GRBs at moderate-to-high redshift has important implications for understanding GRBs and for informing the role of future missions (eg. JDEM, LSST). GRB afterglows have proven to be a versatile and unique astrophysical probe in the study of the ISM of distant galaxies, the IGM at z>2, and the end of the reionization epoch. To this end, our proposed semester 2009A ToO program also seeks to uncover a number of damped-Lyman alpha systems as well as improve the (very curious) statistics of strong intervening Mg II absorbers towards GRB sightlines.