!  File:  4047C.PROP
!  Database:  PEPDB
!  Date:  20-FEB-1994:06:28:44

coverpage:

  title_1:         THE ABSORPTION CROSS-SECTIONS OF NEARBY GALAXIES---
    title_2:       REPEAT FOR HOPR#0034
    sci_cat:       QUASARS & AGN
    sci_subcat:    QUASAR ABSORPTION
    proposal_for:  RPT/GO
    longterm:      1
    cont_id:       2553
    pi_title:      DR.
    pi_fname:      J. CHRIS
    pi_lname:      BLADES
    pi_inst:       SPACE TELESCOPE SCIENCE INSTITUTE
    pi_country:    USA
    pi_phone:      301-338-4805
    keywords_1:    NEARBY GALAXIES, ABSORPTION CROSS-SECTIONS,
    keywords_2:    INTERSTELLAR MEDIUM, ABSORPTION LINES, HALOS, DISKS, QSOS
    hours_pri:     4.39
    num_pri:       1
    hrs:           Y
    pi_position:   ASTRONOMER
    off_fname:     HERVEY
    off_mi:        S.
    off_lname:     STOCKMAN, JR.
    off_title:     DEPUTY DIRECTOR
    off_inst:      SPACE TELESCOPE SCIENCE INSTITUTE
    off_addr_1:    3700 SAN MARTIN DRIVE
    off_city:      BALTIMORE
    off_state:     MD
    off_zip:       21218
    off_country:   USA
    off_phone:     301-338-4730
    off_telex:     6849101
! end of coverpage

abstract:

    line_1:        Absorption redshift systems found in the spectra of QSOs with
    line_2:        Zabs<Zem are generally thought to arise in intervening galaxies.
    line_3:        They can provide unique information on the physical conditions and
    line_4:        distribution of galaxies at earlier epochs which otherwise are
    line_5:        difficult to study.  Yet, we have little knowledge of the nature
    line_6:        and extent of absorbing gas in external systems via direct
    line_7:        observations of QSOs shining through intervening galaxies.  In this
    line_8:        proposal we seek HST time to carry out a statistical determination
    line_9:        of the sizes of halos of nearby galaxies to an equivalent width
    line_10:       limit of 35 mA in C IV and 70 mA in MgII absorption, for direct
    line_11:       comparisons with estimates established from high-redshift QSO
    line_12:       systems.  For this purpose, we have assembled samples of background
    line_13:       QSOs close to low-redshift galaxies for both CIV and MgII.
    line_14:       In many cases, these GSO-galaxy pairs were found by ourselves
    line_15:       either through searching UK Schmidt objective prism plates or
    line_16:       literature surveys.

!
! end of abstract

general_form_proposers:

  lname:           BOWEN
    fname:         DAVID
    title:         CI
    inst:          SPACE TELESCOPE SCIENCE INSTITUTE
    country:       USA

!

  lname:           PETTINI
    fname:         MAX
    title:         CI
    inst:          ANGLO-AUSTRALIAN OBSERVATORY
    country:       AUSTRALIA
    esa:           Y

!

  lname:           BLADES
    fname:         J. CHRIS
    title:         PI
    inst:          SPACE TELESCOPE SCIENCE INSTITUTE
    country:       USA

!
! end of general_form_proposers block

general_form_text:

  question:        2
    section:       1
    line_1:        The narrow metal absorption lines that are commonly found in the
    line_2:        spectra of QSOs are generally thought to arise in intervening
    line_3:        matter associated with galaxies in the line of sight.  If this
    line_4:        interpretation is correct then QSO spectra provide a unique tool
    line_5:        to probe the physical conditions and distribution
    line_6:        of galaxies at earlier epochs, where they cannot otherwise be
    line_7:        observed. Yet, we have little direct knowledge of the intervening
    line_8:        material.  For  example, it is not clear if the metal-line
    line_9:        systems are formed predominantly in the halos of galaxies broadly
    line_10:       similar to present-day spirals.
    line_11:       Otherinterpretations suggest they may arise (i) in galaxies still
    line_12:       undergoing gravitational collapse, (ii) in dwarf galaxies, (iii)
    line_13:       in cooling flows in rich clusters of galaxies, or (iv) in material
    line_14:       tidally stripped in interacting galaxies (c.f. the Magellanic
    line_15:       Stream). The unique capabilities of HST allow us to devise a simple
    line_16:       observational test of whether the metal-line systems arise in
    line_17:       galaxies similar to our own. With HST we  shall observe directly
    line_18:       the absorption properties of nearby galaxies of different
    line_19:       morphological types and in different environments.  We will be
    line_20:       able to recognize clearly the nature of the gas producing the
    line_21:       metal-lines in QSO spectra and subsequently identify the
    line_22:       evolutionary effects in the interstellar media of galaxies over a
    line_23:       significant fraction of the age of the Universe.

!

  question:        2
    section:       2
    line_1:        Our observations will yield the basic data set to make full use of
    line_2:        QSOs as probes of the early universe; it is precisely the lack of
    line_3:        information on metal-line systems in present-day galaxies which
    line_4:        has limited the interpretation of QSO absorption line spectra
    line_5:        until now.
    line_6:        2. Goals Of Proposed Program
    line_7:        We wish to obtain high-resolution spectra of the brightest
    line_8:        background QSOs in our sample of QSO-galaxy pairs (or groupings)
    line_9:        with the aim of measuring the strengths and profiles of
    line_10:       interstellar C IV and Mg II absorption lines formed in the
    line_11:       foreground galaxies.  We propose to use the R = 20,000 mode of
    line_12:       the GHRS.  The good resolution and sensitivity
    line_13:       of this spectrograph will allow us to distinguish between local
    line_14:       absorption in our Galaxy and that of the intervening system.
    line_15:       (The galactic absorption is of considerable interest, in its own
    line_16:       right, of course.)  To achieve the detection limits necessary we
    line_17:       shall bin up the data from 15 to 45 km/sec
    line_18:       which we consider optimum for the goals of this program.
    line_19:       While the measurement of line equivalent widths is our main aim,
    line_20:       at this resolution we shall be sensitive to the velocity
    line_21:       structure of the absorption and will be able to deduce ion column
    line_22:       densities by modelling the line profiles.  Our calculated exposure

!

  question:        2
    section:       3
    line_1:        times are aimed at setting 3 sigma equivalent
    line_2:        width limits of 35 mA in C IV and 70 mA in Mg II.  These limits are
    line_3:        superior to those achieved for surveys of metal-line systems in
    line_4:        high redshift QSOs and both allow for and provide a stimulus to
    line_5:        improvement in these data in future years.
    line_6:        3.   TAC Comments:
    line_7:        Impressive ground-based work was carried out in preparation.
    line_8:        Worried about need for HRS to just detect lines-these lines may be
    line_9:        saturated, so that detailed study of the line profiles may not be
    line_10:       possible.  The statistical issue may be answered by FOS.
    line_11:       Recommendations: Eliminate 2 GTO Targets: 0955+326, 1302-102.

!

  question:        5
    section:       1
    line_1:        I HAVE REQUESTED EVERY ACQ BE DARK TIME.  THIS WAS BECAUSE OF MY CONCERN THAT
    line_2:        GEOCORONAL LYMAN ALPHA MAY CONTAMINATE THE TARGET ACQUISITION.  I SHALL REQUEST
    line_3:        THE GHRS TEAM TO LOOK AT THIS PROBLEM SOME MORE.  IF IT BECOMES IMPOSSIBLE TO
    line_4:        SCHEDULE THIS PROGRAM PLEASE LET ME KNOW.

!
!end of general form text

general_form_address:

  lname:           BLADES
    fname:         J. CHRIS
    title:         DR.
    category:      PI
    inst:          SPACE TELESCOPE SCIENCE INSTITUTE
    addr_1:        3700 SAN MARTIN DRIVE
    city:          BALTIMORE
    state:         MD
    zip:           21218
    country:       USA
    phone:         301-338-4805
    telex:         6849101

!
! end of general_form_address records

fixed_targets:

    targnum:       1
    name_1:        0219+428
    descr_1:       E,313,314
    pos_1:         RA= 02H 22M 39.62S +/- 0.3",
    pos_2:         DEC= +43D 2' 7.98" +/- 0.3"
    equinox:       2000
    rv_or_z:       Z=0.444
    comment_1:     PLATE-ID = O1WN
    fluxnum_1:     1
    fluxval_1:     V=15.5
    fluxnum_2:     2
    fluxval_2:     F-CONT(2800) = 4E-15

!
! end of fixed targets

! No solar system records found

! No generic target records found

exposure_logsheet:

    linenum:       1.000
    targname:      0219+428
    config:        HRS
    opmode:        ACQ
    aperture:      2.0
    sp_element:    MIRROR-N2
    num_exp:       1
    time_per_exp:  9S
    fluxnum_1:     1
    priority:      1
    param_1:       SEARCH-SIZE=3
    param_2:       FAINT=300
    param_3:       LOCATE=YES
    req_1:         CYCLE 1;
    req_2:         ONBOARD ACQ FOR 2;
    req_3:         DARK TIME

!

    linenum:       2.000
    targname:      0219+428
    config:        HRS
    opmode:        ACCUM
    aperture:      2.0
    sp_element:    G270M
    wavelength:    2852-2870
    num_exp:       10
    time_per_exp:  1152S
    s_to_n:        7
    s_to_n_time:   11520S
    fluxnum_1:     1
    priority:      1
    param_1:       COMB=FOUR
    param_2:       FP-SPLIT=TWO
    param_3:       STEP-PATT=DEF
    req_1:         CYCLE 1

!
! end of exposure logsheet

! No scan data records found