8739(  1) - 12/30/99 13:01  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      8739
                                                       Version: 1
                                                       Check-in Date: 30-Dec-1999
                                                                      12:31:09

1.Proposal Title:
Absolute Proper Motion of the Fornax Dwarf Spheroidal
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2. Proposal For  3. Cycle
AR               9
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4. Investigators
                                                                                     Contact?
    PI: Dana Dinescu                      University of Virginia
   CoI: Prof. Steven Majewski             University od Virginia                        N
   CoI: Dr. Terrence Girard               Yale University                               N

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5. Abstract

We propose to measure the absolute proper motion of the Fornax dwarf spheriodal
using HST archived images as second-epoch material, and a combination of Palomar 200
-inch and Du Pont 100-inch photographic plates as a first and intermediate epoch
respectively. This project is motivated by the large number of fields taken with
WFPC2 between 1994 and 1999 in the area of the Fornax dwarf, primarily targeted at
Fornax globular clusters. In addition to these data, the archive contains WFPC2
parallel data as well as a field with a QSO. For our first epoch we have the plate
material that provides an excellent time baseline (up to 50 years) at a plate scale
that allows high-precision astrometry for relatively crowded fields. We estimate to
obtain a proper-motion error between 0.05 and 0.09 mas yr^-1, a value that depends
primarily on the number of extragalactic objects found on all of the WFPC2 fields,
at the limiting magnitude of the plate material (B ~ 22.5). This proper-motion
accuracy will provide tangential velocities of uncertainties between 30 and 54 km s^
-1, which will 1) obtain a dynamical estimate of the mass of the Galaxy as derived
from one of the very distant satellites and, 2) allow the study of the orbital
parameters of the Fornax dwarf and therefore test its kinematical association with
the Fornax-Leo-Sculptor stream proposed by Lynden-Bell.
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                                                8739(  1) - 12/30/99 13:01  - [  2]

            Summary Form for Proposal  8739

  Item                         Used in this proposal
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  Proposal Category            AR
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