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A Robust determination of the time delay in 0957+561a,b and a measurement of the global value of Hubble's constant
Continued photometric monitoring of the gravitational lens system 0957+561A, B in the g and r bands with the Apache Point Observatory (APO) 3.5 m telescope during 1996 shows a sharp g-band event in…
MG0414+0534: A Dusty Gravitational Lens
The gravitational lens system MG0414+0534 has an unexceptional four-image lensing geometry; however, the optical counterparts of the radio images are exceedingly red, with spectra unlike that of any…
Vegetation's red edge: a possible spectroscopic biosignature of extraterrestrial plants.
This work presents Earthshine observations from Apache Point Observatory to emphasize that time variability is key to detecting weak surface biosignatures such as the vegetation red edge, and implies that future terrestrial-planet-characterizing space missions should obtain data that allow time-varying, sharp spectral features at unknown wavelengths to be identified.
A gravitationally lensed quasar with quadruple images separated by 14.62 arcseconds
The discovery of a lensed quasar, SDSS J1004 + 4112, which has a maximum separation between the components of 14.62 arcsec is reported, fully consistent with theoretical expectations based on the cold-dark-matter model.
The Statistics of gravitational lenses: The Distributions of image angular separations and lens redshifts
An analytical calculation is presented which determines the probability that the light from a distant quasar can be lensed by objects in a different redshift range. Three types of information are…
A Gravitational Lens Candidate With an Unusually Red Optical Counterpart
The properties of the strong radio source MG0414 + 0534 are described. It is found to display many of the properties expected in a gravitational lens system. At radio wavelengths and 0.5-arcsec…
Remnants of the quasars.
Assuming a standard black hole accretion model for quasars, we estimate the present total mass density, rho sub BH, of quasar remnants using recent observations of quasar populations and of typical…
Measurement of Spin-Orbit Alignment in an Extrasolar Planetary System
We determine the stellar, planetary, and orbital properties of the transiting planetary system HD 209458 through a joint analysis of high-precision radial velocities, photometry, and timing of the…
Measurement of the Spin-Orbit Alignment in the Exoplanetary System HD 189733
We present spectroscopy of a transit of the exoplanet HD 189733b. By modeling the Rossiter-McLaughlin effect (the anomalous Doppler shift due to the partial eclipse of the rotating stellar surface),…