7544(  1) - 12/14/96 00:57  - [  0]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      7544
                                                       Version: 1
                                                       Check-in Date: 13-Dec-1996
                                                                      18:21:12

1.Proposal Title:
Tangential Velocities of Globular
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2. Scientific Category   3. Proposal For  4. Cycle
STELLAR POPULATIONS         AR               7
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5. Investigators
                                                                                     Contact?
    PI: William F. van Altena             Yale University
   CoI: Dana I. Dinescu                   Yale University                               N
   CoI: Terrence M. Girard                Yale University                               N

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6. Abstract

The HST archival exposures of globular clusters provide a significant source of
potential first-epoch observations for determination of high-accuracy absolute
proper-motions of globular clusters, in a relatively short time interval (3-5
years). We propose here to perform the preliminary tasks of searching the archive
for all appropriate WFPC2 images, and processing these images for the purposes of
galaxy detection and image centroiding accuracy. The goal is to produce a list of
globular clusters for which second-epoch observations - which we will propose in
future Cycles - will produce absolute proper motions with accuracies between 0.1 and
0.5 mas yr^-1 and which are tied directly to galaxies. These will translate into
velocity errors of from a few kms^-1 to a few tens of kms^-1, which will make
possible studies of halo substructure and - for higher accuracies - allow detailed
studies of orbits and implications for disk-shocking and destruction processes of
globular clusters. The crucial parameter that will determine the proper-motion
accuracies is the number of reference galaxies present. The primary effort and
emphasis of this project will be the determination of optimal procedures for
detecting these galaxies, the evaluation of centering algorithms and their
accuracies, and finally the application of the adopted procedures to the archived
globular cluster exposures.
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  Data Distribution

  Media:           ELECTRONIC
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:
  Email:                                                              ,
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                                                7544(  1) - 12/14/96 00:57  - [  1]

            Summary Form for Proposal  7544

  Item                         Used in this proposal
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  Proposal Category            AR
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  Scientific Category          STELLAR POPULATIONS
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