About the CASTLe Survey

The original CfA-Arizona Space Telescope Lens Survey (CASTLeS) was a collaboration between scientists at the Harvard-Smithsonian Center for Astrophysics and the University of Arizona. We carried out a complete survey of all known galaxy-mass gravitational lens systems (those with image separations of less than 10 arcseconds). We used the Hubble Space Telescope to obtain deep, high-resolution images in the optical and near infrared, using NICMOS/NIC2 for H band observations and WFPC2/PC1 for V and I band images where they do not yet exist. Since the original survey, the number of lens systems have grown dramatically. We continue to update these web pages with the latest HST observations of lens systems.

Among our project goals are to:

  • identify simple lens systems for estimating the Hubble constant
  • obtain photometric redshifts for the lens galaxies
  • measure the mass to light ratio of lens galaxies
  • compare dark matter and stellar light distributions in lens galaxies
  • probe the interstellar medium in the lens galaxies
  • find as-yet undetected lens galaxies.
This information can be used to address a number of problems in modern cosmology and galaxy evolution.
  • Emilio Falco, CfA
  • Chris Impey, Arizona
  • Christopher Kochanek, Ohio State
  • Brian McLeod, CfA
  • Hans-Walter Rix, MPIA