9958(  1) - 04/04/03 10:38  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9958
                                                       Version: 1
                                                       Check-in Date: 04-Apr-2003
                                                                      10:37:40

1.Proposal Title:
An astrometric standard field in omega Cen
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Rosemary Wyse                     The Johns Hopkins University
   CoI: Dr. Terrence Girard               Yale University                               N
   CoI: Dr. Anton Koekemoer               Space Telescope Science Institute             N
   CoI: Dr. Imants Platais                The Johns Hopkins University                  N
   CoI: Dr. Nicholas Suntzeff             National Optical Astronomy Observatories -    N
                                          CTIO
   CoI: Dr. Donald Terndrup               Ohio State University                         N

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5. Abstract

We propose to obtain a high-precision astrometric standard in a two-step procedure.
First, we will create a ground-based astrometric standard field around omega Cen
down to V=22 with a 3 mas accuracy in positions and better than 0.5 mas/yr in proper
motions. This standard will be used to obtain precise absolute plate solutions for
selected WFPC2 CCD frames and refine the self-calibrated mean distortion solution
for the WFPC2 CCD chips. This will eliminate systematic errors inherent in the self-
calibration techniques down to the rms=0.3 mas level, thus opening new opportunities
to perform precision astrometry with WFPC2 alone or in combination with the other
HST imaging instruments. We will also address the issue of the distortion's
variation which has a paramount significance for space astrometry such as
spearheaded by the HST or being under development (SIM, GAIA). Second, all reduced
WFPC2 CCD frames will be combined into the two field catalogs (astrometric flat
fields) of positions in omega Cen of unprecedented precision (s.e.=0.1 mas) down to
V=22 and will be available to the GO community and readily applicable to calibrating
the ACS.
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                                                9958(  1) - 04/04/03 10:38  - [  2]

            Summary Form for Proposal  9958

  Item                         Used in this proposal
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  Proposal Category            AR
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