10665(  1) - 04/05/05 12:26  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10665
                                                       Version: 1
                                                       Check-in Date: 05-Apr-2005
                                                                      16:25:57

1.Proposal Title:
Legacy HST Spectroscopy of the Low Redshift Intergalactic Medium
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2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               14        <none>
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5. Investigators
                                                                                     Contact?
    PI: Dr. Chris D. Impey                University of Arizona
   CoI: Mr. Andrew R. Marble              University of Arizona                         N

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6. Abstract

We propose a homogeneous analysis of all HST spectra of quasars and AGN that probe
the low redshift intergalactic medium (z < 0.4). Data taken at moderate resolution
with each of the three spectroscopic instruments -- FOS, GHRS, and STIS -- will be
included. The analysis will involve 316 targets, span a total redshift path of ~110
and yield an estimated 1500 Lyman-alpha absorbers. In this redshift range, it will
incease the number of absorbers by a factor of 15 over the HST Absorption Line Key
Project. Data products include co-added and calibrated spectra, continuum fits,
absorption line lists, and line identifications, all on a web site that includes
hyperlinked information from NED and ADS. About 90% of the sightlines are in regions
covered by the SDSS, 2dF and 6dF surveys. This Archive Legacy database will
facilitate a range of scientific investigations, including (a) studies of the
relationship between luminous baryons in galaxies and diffuse baryons in the IGM,
(b) comparisons between the observations and simulations that incorporate gas
dynamics, (c) measures of cosmic variance in structure on the largest scales, (d)
new tests of the gravitational instability paradigm, (e) accurate determination of
the proximity effect at low redshift, and (f) measurements of the chemical
enrichment of the IGM. With no prospect of sensitive UV spectroscopy in the
forseeable future, this dataset will form part of HST's unique and enduring legacy.
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                                                10665(  1) - 04/05/05 12:26  - [  2]

            Summary Form for Proposal  10665

  Item                         Used in this proposal
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  Proposal Category            AR
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