5798(  0) - 07/18/95 18:01  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      5798
                                                       Version: **********
                                                       Check-in Date: **********

1.Proposal Title:
The Evolution of Early-Type Galaxies in Distant Clusters
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2. Scientific Category   3. Proposal For  4. Cycle
Galaxies & Clusters         AR               5
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5. Investigators
                                                                                     Contact?
    PI: Garth Illingworth                 Lick Observatory, University of
                                          California, Santa Cruz
   CoI: Marijn Franx                      Kapteyn Astronomical Institute                N
   CoI: Dan Kelson                        Lick Observatory, University of               N
                                          California, Santa Cruz

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6. Abstract

We propose to utilize HST data for  quantitative studies that will allow a very
rigorous examination to be made of the evolutionary state of galaxies in
intermediate redshift clusters. The Fundamental Plane (FP) of early-type galaxies is
one of the most sensitive tests for galaxy evolution. This is because of its low
intrinsic scatter for nearby cluster galaxies. It can be used to accurately measure
the luminosity evolution of galaxies, and the change of M/L with time. We have
started a program to determine internal velocity dispersions of galaxies in six
rich, X-ray selected clusters at redshifts between 0.3-0.6 with the Keck telescope.
This project is part of the thesis for graduate student, Dan Kelson. We propose here
to use the high resolution HST data from the archive on two X-ray clusters at z=0.31
and z=0.38 to determine very accurate scale lengths, surface brightnesses and
morphologies.  These results will be combined with Keck spectroscopic data for an FP
analysis. The first Keck data on CL2137-23 is already in hand, and A370 is to be
studied in an already-allocated run in November. Both A370 and CL2137-23 are
gravitational lensing clusters and have a rich entourage of arclets.  While the
galaxies are our highest priority, we plan to use unassigned slitlets in the Keck
slitmasks to determine redshifts and spectral characteristics of the arclets.
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  Observations Description
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  Real Time Justification
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  Calibration Justification
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  Additional Comments
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                                                5798(  0) - 07/18/95 18:01  - [  2]

  Data Distribution

  Media:           8MM
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:        UPS
  Email:                                                              ,
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                                                5798(  0) - 07/18/95 18:01  - [  3]

            Summary Form for Proposal  5798

  Item                         Used in this proposal
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  Proposal Category            AR
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  Scientific Category          Galaxies & Clusters
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