Showing papers by "Gerry Gilmore published in 1998"

The Optical Afterglow of GRB 971214: R and J Photometry

Abstract: We present an R- and J-band photometry of an optical transient that is likely to be associated with the gamma-ray burst event GRB 971214. Our first measurement took place 13 hr after the gamma-ray event. The brightness decayed with a power-law exponent α=-1.20±0.02, which is similar to those of GRB 970228 andGRB 970508, which had exponents of α=-1.10±0.04 and α=-1.141±0.014, respectively. The transient decayed monotonically during the first 4 days following the gamma-ray event in contrast with the optical transient associated with GRB 970508, which increased in brightness, peaking 2 days after the burst, before settling to a power-law decay.

The Optical Afterglow of GRB 971214: R and J Photometry

Abstract: We present an R-band and J-band photometry of an optical transient which is likely to be associated with the gamma-ray burst event GRB 971214. Our first measurement took place 13 hours after the gamma-ray event. The brightness decayed with a power-law exponent alpha = -1.20 +- 0.02, which is similar to those of GRB 970228 and GRB 970508 which had exponents of alpha = -1.10 +- 0.04 and alpha = -1.141 +- 0.014 respectively. The transient decayed monotonically during the first four days following the gamma-ray event in contrast with the optical transient associated with GRB 970508 which increased in brightness, peaking two days after the burst, before settling to a power-law decay.

GAIA: Origin and Evolution of the Milky Way

Abstract: GAIA is a short-listed candidate for the ESA Cornerstone mission C5, meeting the ESA Survey Committee requirement for an observatory mission, dedicated to astrometry, providing 10 micro-arcsecond accuracy at 15th magnitude. The GAIA mission concept follows the dramatic success of the ESA HIPPARCOS mission, utilising a continuously scanning spacecraft, accurately measuring 1-D coordinates along great circles, in (at least) two simultaneous fields of view, separated by a known angle. These 1-D relative coordinates are later converted to the five astrometric parameters of position and motions in a global analysis. GAIA will provide precise astrometry and multi-colour photometry for all the one billion stars, quasars, and compact galaxies to I=20 on the sky. GAIA will additionally provide the sixth phase-space parameter, radial velocity, from a slitless spectroscopic survey of most stars brighter than about magnitude 17. The technical challenges are considerable, but achievable. The scientific returns are spectacular, with greatest impact in the study of stellar populations and dynamical structure of the galaxies of our Local Group, and in providing the first complete census of the stars and massive planets in the Solar neighbourhood. GAIA will revolutionise our knowledge of the origin and evolution of our Milky Way Galaxy, and of the distribution of planetary systems around other stars.

Mass-Losing AGB Stars and Young Stars in the Isogal Survey

Abstract: ISOGAL is the first near+mid-infrared, high-resolution imaging survey of the inner disk and bulge of the Milky Way Galaxy (Perault et al. 1996). The ISO satellite, and especially ISOCAM, allows a quantum jump in observational analyses of Galactic structure and stellar populations, star formation and infrared properties of the interstellar medium, especially in the most obscured regions of the inner Galactic disk. The combination of ISOCAM data with DENIS (Epchtein et al. 1997) IJK data allows characterisation of the stellar populations.