!  File:  4835C.PROP
!  Database:  PEPDB
!  Date:  23-FEB-1994:05:30:14

coverpage:

  title_1:         COMPOSITION OF GAS IN INDIVIDUAL INTERSTELLAR CLOUDS:
    title_2:       CYCLE 3 HIGH PRIORITY OBSERVATIONS
    sci_cat:       INTERSTELLAR MEDIUM
    sci_subcat:    ABSORPTION LINES
    proposal_for:  AUG/OS
    cont_id:       3444
    pi_title:      PROF.
    pi_fname:      LYMAN
    pi_lname:      SPITZER
    pi_inst:       PRINCETON UNIVERSITY
    pi_country:    USA
    pi_phone:      (609) 258-3809
    keywords_1:    INTERSTELLAR LINES
    hours_pri:     6.21
    num_pri:       1
    hrs:           Y
    pi_position:   PROFESSOR EMERITUS
! end of coverpage

abstract:

    line_1:        Column densities of interstellar atoms of 17 atomic species of 10
    line_2:        elements will be measured in the line-of-sight to 1 early-type star in
    line_3:        the galactic halo using the Goddard High Resolution Spectrograph to
    line_4:        obtain precise measures in the ultraviolet with the highest available
    line_5:        spectral resolution.  These data will be analyzed to determine relative
    line_6:        abundances in the several individual clouds present along each line of
    line_7:        sight, and thus to determine how the composition of the gas in such
    line_8:        clouds and the various physical processes occurring vary with cloud
    line_9:        parameters such as H column density, velocity, ionization level, and
    line_10:       distance z from the galactic plane.  This information should help to
    line_11:       clarify the many physical processes occurring in interstellar gas.  In
    line_12:       particular, measures of stars in the galactic halo should
    line_13:       help to identify the mechanisms responsible for the abundant C IV, Si
    line_14:       IV, and N V known to be present in the interstellar gas at kiloparsec
    line_15:       distances from the galactic plane.  The program should also increase
    line_16:       our understanding of the balance between formation and destruction of
    line_17:       interstellar dust grains.

!
! end of abstract

general_form_proposers:

  lname:           SPITZER
    fname:         LYMAN
    title:         PROF.
    inst:          PRINCETON UNIVERSITY
    country:       USA

!

  lname:           O'DELL
    fname:         C.
    title:         PROF.
    mi:            R.
    inst:          RICE UNIVERSITY
    country:       USA

!
! end of general_form_proposers block

general_form_text:

  question:        3
    section:       1
    line_1:        The observations of one star planned during Cycle 3, and supported
    line_2:        with GTO Augmentation time (under #3444), will in general follow the
    line_3:        pattern set for the two stars to be observed in Cycle 2 (under this
    line_4:        same AUG program).  For each star, a series of interstellar absorption
    line_5:        lines longward of 1800 A will be observed with Echelle B of the GHRS,
    line_6:        giving the highest resolution available (resolving power R about
    line_7:        85,000) for lines of S I, Si II, Mg I, Fe II, Co II, Cr II, Zn II, and
    line_8:        Mn II.  For photometric accuracy, the WSCAN mode will be used to give
    line_9:        three adjacent exposures of each line.  Another series of lines at
    line_10:       shorter wavelengths, between 1120 and 1600 A, will be observed with the
    line_11:       GHRS grating G160M, using the FP-SPLIT routine to obtain subexposures
    line_12:       at four adjacent wavelengths.  Of the many interstellar lines in this
    line_13:       region the following species are of particular interest:  C I, C II, C
    line_14:       IV, N I, N V, O I, Mg II, S II, S III, Si II, Si III, Si IV, P II, P
    line_15:       III, Fe II, and Mn II.  While the resolving power with this grating is
    line_16:       in the range from about 15,000 to 24,000, deconvolution of each
    line_17:       spectrum may almost double the effective R.  For accurate wavelength
    line_18:       calibration, exposures of the calibration lamp spectrum will be taken
    line_19:       at the beginning and end of each series.

!

  question:        4
    section:       1
    line_1:        Much pioneering work on individual interstellar clouds has been done
    line_2:        from the ground.  However, to obtain data on many elements, including
    line_3:        the highly ionized species, requires observations from above the
    line_4:        atmosphere.  The Copernicus satellite made important contributions to
    line_5:        this topic, but its resolving power of 20,000 was insufficient to
    line_6:        resolve clearly many of the individual components in most lines of
    line_7:        sight, although in favorable cases properties of individual clouds were
    line_8:        successfully deduced.  The IUE satellite has been enormously useful for
    line_9:        broad surveys of interstellar absorption, especially for the fainter
    line_10:       stars which could not be observed with Copernicus, but its resolving
    line_11:       power of 10,000 is inadequate for resolving most components.  The HST,
    line_12:       with its resolving power of 85,000 for lines observed with Echelle B,
    line_13:       can answer detailed questions on the physical properties of individual
    line_14:       clouds towards many stars.

!

  question:        5
    section:       1
    line_1:        There are no Realtime Data or Special Scheduling Requests required.

!

  question:        6
    section:       1
    line_1:        There are no Special Calibrations required.

!

  question:        7
    section:       1
    line_1:        To analyze the HST/GHRS data for this ongoing project, a dedicated Sun
    line_2:        SPARCstation 1 has been obtained.  The STSDAS software (running as part
    line_3:        of the IRAF system) and the IDL language have both been implemented
    line_4:        on the SPARCstation.
    line_6:        As part of the data processing, corrections will be made for a variety
    line_7:        of effects, including scattered light, fixed pattern noise, and shift
    line_8:        of wavelength calibration with temperature.  Data analysis will
    line_9:        determine for each line the function Nr(v), the apparent column density
    line_10:       of species r per unit velocity interval, as a function of Doppler-shift
    line_11:       velocity v.  Comparison of Nr(v) between lines of different f-values
    line_12:       but with the same lower state yields a correction of these values for
    line_13:       saturation, if the corrections are not large.

!

  question:        8
    section:       1
    line_1:        No additional comments or requests.

!

  question:        9
    section:       1
    line_1:        PREVIOUS HST PROGRAMS: GTO 1071, 3215, and AUG 3444 "Composition of
    line_2:        Gas in Individual Interstellar Clouds".  These identification numbers,
    line_3:        for observations in Cycles 0, 1, and 2, designate the ongoing project
    line_4:        for which the present proposal represents further Augmentation time
    line_5:        observations under #3444.
    line_7:        MAIN RESULTS OBTAINED FROM PREVIOUS RELATED PROGRAMS:  Two stars, HD
    line_8:        68273 (Gamma-2 Velorum) and HD 93521, were observed for the program
    line_9:        GTO 1071 during Cycle 0.  Analysis of these data has yielded a
    line_10:       new strategy for removing the effects of scattered light from GHRS
    line_11:       echelle data and a very effective technique for correcting for fixed
    line_12:       pattern noise in the data, an effect important for the brighter stars,
    line_13:       for which S/N can be about 100 or more.  In the halo star HD93521,
    line_14:       1500 pc from the galactic plane, the observed widths of the
    line_15:       C IV and Si IV absorption features are 50 km/sec (FWHM), as compared
    line_16:       with 7 km/sec for a narrow S II component.  Measures of the
    line_17:       low-ionization lines (such as S II, Si II, Fe II) have given detailed
    line_18:       information on the depletion of elements from the gas as a result
    line_19:       of condensation on solid grains, and suggest that iron orthosilicate
    line_20:       is a primary constituent of these grains.  The temperature and density
    line_21:       of the intestellar gas have also been determined.

!

  question:        9
    section:       2
    line_1:        PUBLICATIONS RESULTING FROM THE ABOVE DATA:  A brief description of
    line_2:        these data and of their technical aspects has appeared in the STScI
    line_3:        Newsletter, June 1991 (Vol. 8, No. 2).  The observed profiles of the
    line_4:        C IV and Si IV features in HD93521 are presented in Ap.J. Letters
    line_5:        (May 10, 1992), and their possible interpretation discusssed.  A full
    line_6:        discussion of the HD 93521 results is scheduled to appear in the Ap.J.
    line_7:        (May 20, 1993).

!

  question:        10
    section:       1
    line_1:        The participation of L. Spitzer, now Senior Research Astronomer at
    line_2:        Princeton University, is without charge to the Project; he expects to
    line_3:        devote nearly all his research time to this work.  The chief annual
    line_4:        cost to the Project is the full-time salary of E.L. Fitzpatrick,
    line_5:        now Research Astronomer with continuing appointment.  The
    line_6:        Department of Astrophysical Sciences contributed funds toward his
    line_7:        salary during several years before full NASA funding (by subcontract
    line_8:        with O'Dell's home institution, the Rice University of Technology)
    line_9:        became available.  Computer peripherals, including tape drives and a
    line_10:       laser printer, are available at the Department for a small monthly
    line_11:       charge.

!
!end of general form text

general_form_address:

  lname:           SPITZER
    fname:         LYMAN
    title:         PROF.
    category:      PI
    inst:          PRINCETON UNIV. OBSERVATORY
    addr_1:        PEYTON HALL
    city:          PRINCETON
    state:         NJ
    zip:           08544
    country:       USA
    phone:         609-258-3809

!

  lname:           O'DELL
    fname:         C.
    mi:            R.
    title:         PROF.
    inst:          RICE UNIVERSITY
    addr_1:        DEPT. OF SPACE PHYSICS & ASTRONOMY
    addr_2:        P.O. BOX 1892
    city:          HOUSTON
    state:         TX
    zip:           77251
    country:       USA
    phone:         713-527-8101 X3633
    telex:         556457

!
! end of general_form_address records

fixed_targets:

    targnum:       2
    name_1:        HD149881
    descr_1:       A,113,G,508,911
    pos_1:         RA=16H34M40.58S +/- .1S,
    pos_2:         DEC=14D34'30.1" +/- 1.0"
    equinox:       1950
    pm_or_par:     NO
    comment_1:     SPECTRAL TYPE B0.5 II
    fluxnum_1:     1
    fluxval_1:     V=7.03,E(B-V)=0.07
    fluxnum_2:     2
    fluxval_2:     F-CONT(1300)=2.9+/-0.6E-10

!
! end of fixed targets

! No solar system records found

! No generic target records found

exposure_logsheet:

    linenum:       1.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1148.0
    num_exp:       2
    time_per_exp:  308S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR
    req_1:         SEQ 1-7 NO GAP
    comment_1:     EXPOSURE TIME IN LINE 1 YIELDS S/N
    comment_2:     =43 PER 3 KM/S BIN PER SUBEXPOSURE
    comment_3:     FOR A STANDARD STAR WITH F-CONT(1300)
    comment_4:     =1.0E-8 USING MEASURED HST SENSITIVITY

!

    linenum:       2.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1195.0
    num_exp:       1
    time_per_exp:  287S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR
    comment_1:     EXPOSURE TIMES IN LINES 2-7 YIELD S/N
    comment_2:     =87 PER 3 KM/S BIN PER SUBEXPOSURE
    comment_3:     FOR A STANDARD STAR WITH F-CONT(1300)
    comment_4:     =1.0E-8 USING MEASURED HST SENSITIVITY

!

    linenum:       3.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1252.0
    num_exp:       1
    time_per_exp:  134S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR

!

    linenum:       4.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1315.6
    num_exp:       1
    time_per_exp:  107S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR

!

    linenum:       5.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1347.0
    num_exp:       1
    time_per_exp:  129S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR

!

    linenum:       6.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1392.0
    num_exp:       1
    time_per_exp:  164S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR

!

    linenum:       7.000
    sequence_1:    DEFINE
    sequence_2:    D-1A
    targname:      #
    config:        HRS
    opmode:        ACCUM
    aperture:      0.25
    sp_element:    G160M
    wavelength:    1560.0
    num_exp:       1
    time_per_exp:  233S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO,
    param_3:       FP-SPLIT=DSFOUR

!

    linenum:       8.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    1804.92-1807.08
    num_exp:       1
    time_per_exp:  186S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.72
    req_1:         SEQ 8-14 NO GAP
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 8 IS
    comment_2:     EQUIVALENT TO 8 CARROUSEL STEPS.
    comment_3:     EXPOSURE TIMES IN LINES 8-14 YIELD S/N
    comment_4:     =100 PER 3 KM/S BIN PER SUBEXPOSURE
    comment_5:     FOR A STANDARD STAR WITH F-CONT(1300)
    comment_6:     =1.0E-8 USING MEASURED HST SENSITIVITY

!

    linenum:       9.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    1825.95-1828.05
    num_exp:       1
    time_per_exp:  186S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.70
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 9
    comment_2:     IS EQUIVALENT TO 8 CARROUSEL STEPS.

!

    linenum:       10.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    2024.51-2026.79
    num_exp:       1
    time_per_exp:  81S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.76
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 10
    comment_2:     IS EQUIVALENT TO 8 CARROUSEL STEPS.
    comment_3:     VACUUM WAVELENGTHS USED IN LINE 10.

!

    linenum:       11.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    2058.21-2060.79
    num_exp:       1
    time_per_exp:  90S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.86
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 11
    comment_2:     IS EQUIVALENT TO 8 CARROUSEL STEPS.
    comment_3:     VACUUM WAVELENGTHS USED IN LINE 11.

!

    linenum:       12.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    2259.49-2262.10
    num_exp:       1
    time_per_exp:  45S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.87
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 12
    comment_2:     IS EQUIVALENT TO 8 CARROUSEL STEPS.
    comment_3:     VACUUM WAVELENGTHS USED IN LINE 12.

!

    linenum:       13.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    2370.71-2373.35
    num_exp:       1
    time_per_exp:  66S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.88
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 13
    comment_2:     IS EQUIVALENT TO 8 CARROUSEL STEPS.
    comment_3:     VACUUM WAVELENGTHS USED IN LINE 13.

!

    linenum:       14.000
    sequence_1:    DEFINE
    sequence_2:    BR-3B
    targname:      #
    config:        HRS
    opmode:        WSCAN
    aperture:      0.25
    sp_element:    ECH-B
    wavelength:    2601.88-2604.67
    num_exp:       1
    time_per_exp:  105S
    s_to_n:        #
    fluxnum_1:     2
    priority:      #
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO,
    param_3:       WAVE-STEP=0.93
    comment_1:     "WAVE-STEP" IN COLUMN 9 OF LINE 14
    comment_2:     IS EQUIVALENT TO 8 CARROUSEL STEPS.
    comment_3:     VACUUM WAVELENGTHS USED IN LINE 14.

!

    linenum:       301.000
    targname:      HD149881
    config:        HRS
    opmode:        ACQ
    aperture:      2.0
    sp_element:    MIRROR-A2
    num_exp:       1
    time_per_exp:  1.8S
    priority:      1
    param_1:       BRIGHT=RETURN,
    param_2:       SEARCH-SIZE=3,
    param_3:       LOCATE=YES
    req_1:         ONBOARD ACQUISITION FOR 302;
    req_2:         CYCLE 3 / 301-308
    comment_1:     STEP-TIME=0.2 SEC.

!

    linenum:       302.000
    targname:      HD149881
    config:        HRS
    opmode:        ACQ/PEAKUP
    aperture:      0.25
    sp_element:    MIRROR-A2
    num_exp:       1
    time_per_exp:  40S
    priority:      1
    req_1:         ONBOARD ACQUISITION FOR 303-308
    comment_1:     STEP-TIME=1.6 SEC FROM SIB.

!

    linenum:       303.000
    targname:      WAVE
    config:        HRS
    opmode:        ACCUM
    aperture:      SC2
    sp_element:    G160M
    wavelength:    1190.5
    num_exp:       1
    time_per_exp:  60S
    priority:      1
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO
    req_1:         SEQ 303-305 NO GAP;
    req_2:         CALIB FOR 304

!

    linenum:       304.000
    sequence_1:    USE
    sequence_2:    D-1A
    targname:      HD149881
    time_per_exp:  X4.42
    s_to_n:        31
    priority:      1
    comment_1:     THE MULTIPLICATIVE FACTOR 4.42 FOR ALL
    comment_2:     D-1A EXPOSURES FOR THIS STAR HAS BEEN
    comment_3:     CALCULATED TO GIVE S/N=31 PER 3 KM/S
    comment_4:     BIN PER SUBEXPOSURE FOR MOST SPECTRAL
    comment_5:     FEATURES, USING THE HRS SENSITIVITY AS
    comment_6:     MEASURED IN CYCLE 0.

!

    linenum:       305.000
    targname:      WAVE
    config:        HRS
    opmode:        ACCUM
    aperture:      SC2
    sp_element:    G160M
    wavelength:    1560.0
    num_exp:       1
    time_per_exp:  60S
    priority:      1
    param_1:       STEP-PATT=5,
    param_2:       COMB=TWO
    req_1:         CALIB FOR 304

!

    linenum:       306.000
    targname:      WAVE
    config:        HRS
    opmode:        ACCUM
    aperture:      SC2
    sp_element:    ECH-B
    wavelength:    1805.28
    num_exp:       1
    time_per_exp:  10S
    priority:      1
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO
    req_1:         SEQ 306-308 NO GAP;
    req_2:         CALIB FOR 307

!

    linenum:       307.000
    sequence_1:    USE
    sequence_2:    BR-3B
    targname:      HD149881
    time_per_exp:  X4.42
    s_to_n:        36
    priority:      1
    comment_1:     THE MULTIPLICATIVE FACTOR 4.42 FOR ALL
    comment_2:     BR-3B EXPOSURES FOR THIS STAR HAS BEEN
    comment_3:     CALCULATED TO GIVE S/N=36 PER 3 KM/S
    comment_4:     BIN PER SUBEXPOSURE USING THE HRS
    comment_5:     SENSITIVITY AS MEASURED IN CYCLE 0.

!

    linenum:       308.000
    targname:      WAVE
    config:        HRS
    opmode:        ACCUM
    aperture:      SC2
    sp_element:    ECH-B
    wavelength:    2604.81
    num_exp:       1
    time_per_exp:  10S
    priority:      1
    param_1:       STEP-PATT=6,
    param_2:       COMB=TWO
    req_1:         CALIB FOR 307

!
! end of exposure logsheet

! No scan data records found