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    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID 4047c
                                                       Report Date: 09-May-96:19:07
                                                       Version: **********
                                                       Check-in Date: **********

1.Proposal Title:
THE ABSORPTION CROSS-SECTIONS OF NEARBY GALAXIES---  REPEAT FOR HOPR#0034
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2. Scientific Category   3. Proposal For  4. Proposal Type        5. Continuation ID
QUASARS & AGN               RPT/GO           1 Long Term yrs         2553
Sub Category
QUASAR ABSORPTION
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6. Principal Investigator   Institution                    Country    Telephone
Dr. J. chris  Blades        SPACE TELESCOPE SCIENCE INST   USA        301-338-4805
ASTRONOMER
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7. Abstract
Absorption redshift systems found in the spectra of QSOs with Zabs<Zem are generally
thought to arise in intervening galaxies. They can provide unique information on the
physical conditions and distribution of galaxies at earlier epochs which otherwise
are difficult to study.  Yet, we have little knowledge of the nature and extent of
absorbing gas in external systems via direct observations of QSOs shining through
intervening galaxies.  In this proposal we seek HST time to carry out a statistical
determination of the sizes of halos of nearby galaxies to an equivalent width limit
of 35 mA in C IV and 70 mA in MgII absorption, for direct comparisons with estimates
established from high-redshift QSO systems.  For this purpose, we have assembled
samples of background QSOs close to low-redshift galaxies for both CIV and MgII. In
many cases, these GSO-galaxy pairs were found by ourselves either through searching
UK Schmidt objective prism plates or literature surveys.
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8. Scientific Key Words:   NEARBY GALAXIES, ABSORPTION CROSS-SECTIONS, INTERSTELLAR
MEDIUM, ABSORPTION LINES, HALOS, DISKS, QSOS
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9. Est obs time (hours) pri: 4.39     par: 0       10. Num targs pri: 1      par: 0
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11. Instruments requested:  HRS
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I. GENERAL FORM    Proposal 4047c
PI: Dr. J. chris  Blades
Proposal Title:
THE ABSORPTION CROSS-SECTIONS OF NEARBY GALAXIES---  REPEAT FOR HOPR#0034
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1. Proposers:
Proposers                        Institution                       Country       ESA
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Ci David Bowen                   SPACE TELESCOPE SCIENCE           USA
                                 INSTITUTE
Ci Max Pettini                   ANGLO-AUSTRALIAN OBSERVATORY      AUSTRALIA      X
Pi J. Chris Blades               SPACE TELESCOPE SCIENCE           USA
                                 INSTITUTE
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  2. Scientific Justification.
  The narrow metal absorption lines that are commonly found in the spectra of QSOs
 are generally thought to arise in intervening matter associated with galaxies in
 the line of sight.  If this interpretation is correct then QSO spectra provide a
 unique tool to probe the physical conditions and distribution of galaxies at
 earlier epochs, where they cannot otherwise be observed. Yet, we have little
 direct knowledge of the intervening material.  For  example, it is not clear if
 the metal-line systems are formed predominantly in the halos of galaxies broadly
 similar to present-day spirals. Otherinterpretations suggest they may arise (i)
 in galaxies still undergoing gravitational collapse, (ii) in dwarf galaxies,
 (iii) in cooling flows in rich clusters of galaxies, or (iv) in material tidally
 stripped in interacting galaxies (c.f. the Magellanic Stream). The unique
 capabilities of HST allow us to devise a simple observational test of whether the
 metal-line systems arise in galaxies similar to our own. With HST we  shall
 observe directly the absorption properties of nearby galaxies of different
 morphological types and in different environments.  We will be able to recognize
 clearly the nature of the gas producing the metal-lines in QSO spectra and
 subsequently identify the evolutionary effects in the interstellar media of
 galaxies over a significant fraction of the age of the Universe.   Our
 observations will yield the basic data set to make full use of QSOs as probes of
 the early universe; it is precisely the lack of information on metal-line systems
 in present-day galaxies which has limited the interpretation of QSO absorption
 line spectra until now. 2. Goals Of Proposed Program We wish to obtain high-
 resolution spectra of the brightest background QSOs in our sample of QSO-galaxy
 pairs (or groupings) with the aim of measuring the strengths and profiles of
 interstellar C IV and Mg II absorption lines formed in the foreground galaxies.
 We propose to use the R = 20,000 mode of the GHRS.  The good resolution and
 sensitivity of this spectrograph will allow us to distinguish between local
 absorption in our Galaxy and that of the intervening system. (The galactic
 absorption is of considerable interest, in its own right, of course.)  To achieve
 the detection limits necessary we shall bin up the data from 15 to 45 km/sec
 which we consider optimum for the goals of this program. While the measurement of
 line equivalent widths is our main aim, at this resolution we shall be sensitive
 to the velocity structure of the absorption and will be able to deduce ion column
 densities by modelling the line profiles.  Our calculated exposure   times are
 aimed at setting 3 sigma equivalent width limits of 35 mA in C IV and 70 mA in Mg
 II.  These limits are superior to those achieved for surveys of metal-line
 systems in high redshift QSOs and both allow for and provide a stimulus to
 improvement in these data in future years. 3.   TAC Comments: Impressive ground-
 based work was carried out in preparation. Worried about need for HRS to just
 detect lines-these lines may be saturated, so that detailed study of the line
 profiles may not be possible.  The statistical issue may be answered by FOS.
 Recommendations: Eliminate 2 GTO Targets: 0955+326, 1302-102.
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  5. Description of special scheduling requirements.
  I HAVE REQUESTED EVERY ACQ BE DARK TIME.  THIS WAS BECAUSE OF MY CONCERN THAT
 GEOCORONAL LYMAN ALPHA MAY CONTAMINATE THE TARGET ACQUISITION.  I SHALL REQUEST
 THE GHRS TEAM TO LOOK AT THIS PROBLEM SOME MORE.  IF IT BECOMES IMPOSSIBLE TO
 SCHEDULE THIS PROGRAM PLEASE LET ME KNOW.
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11. Address Information
Name:  J. CHRIS  BLADES                                    Category: PI
Institution: SPACE TELESCOPE SCIENCE INSTITUTE
Address:  3700 SAN MARTIN DRIVE
City: BALTIMORE                                 State: MD
Zip Code: 21218                                 Country: USA
Telephone: 301-338-4805
Telex (or e-mail): 6849101
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TARGET LIST    a) Fixed Targets                                                                    ID = 4047c            [  4]
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 1 |     2      |           3           |              4             |  5     |   6    |  7  |              8
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Tar|   Target   |         Target        |            Target          |Coord   | Radial |Acqui|FLX|     Flux data
No |    Name    |       Description     |           Position         |Eqnx    |  Vel.  |Prblm|REF|
   |            |                       |                            |        |        |     |   |
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1   0219+428     E,313,314               RA= 02H 22M 39.62S +/- 0.3", 2000     Z=0.444        1   V=15.5
                                         DEC= +43D 2' 7.98" +/- 0.3"                          2   F-CONT(2800) = 4E-15
     Comments: PLATE-ID = O1WN
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EXPOSURE LOGSHEET                                                                                  ID = 4047c            [  5]
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 1      |   2   |      3    |  4   |   5   |   6   |    7   |   8   |       9       |10 |   11  |   12    |13 |14|        15
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  Line  |  Seq  |   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |   S/N   |Flx|Pr|     Special
 Number | Name  |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |Rel. Time|Ref|  |   Requirements
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1                0219+428    HRS    ACQ     2.0     MIRROR-N2        SEARCH-SIZE=3   1   9S                1   1  CYCLE 1
                                                                     FAINT=300                                    ONBOARD ACQ FOR 2
                                                                     LOCATE=YES                                   DARK TIME
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2                0219+428    HRS    ACCUM   2.0     G270M    2852-   COMB=FOUR       10  1152S   7         1   1  CYCLE 1
                                                             2870    FP-SPLIT=TWO                11520S
                                                                     STEP-PATT=DEF
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            Summary Form for Proposal 4047c                                                                              [  6]

  Item                          Used in this proposal
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  Configurations                HRS
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  Opmodes                       ACQ ACCUM
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  Optional Parameters           SEARCH-SIZE=3 FAINT=300 LOCATE=YES COMB=FOUR FP-SPLIT=TWO STEP-PATT=DEF
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  Proposal for                  RPT/GO
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  S/C Hours                     4.39
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  Scientific Category           QUASARS & AGN
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  Scientific Sub-category       QUASAR ABSORPTION
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  Special Requirements          CYCLE 1; ONBOARD ACQ FOR 2; DARK TIME CYCLE 1
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  Spectral Elements             MIRROR-N2 G270M
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  Target Names                  0219+428
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