! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template
!
!   Refer to the HST Phase II Proposal Instructions to fill this out
!
!   Anything after a "!" is ignored, and may be deleted
!
!   All keywords with multiple entries are comma delimited except the
!   Visit_Requirements and Special_Requirements keywords which can be
!   delimited with carriage returns or semi-colons, but not commas
!
! For help call your Program Coordinator: Alice Berman
!             Phone: 410-338-4462    , E-mail: aberman@stsci.edu
!
! This partially completed template was generated from a Phase I proposal.
!

Proposal_Information                           ! Section 4
              Title:  A NEW ABUNDANCE REFERENCE AT THE PRESENT
                      EPOCH
  Proposal_Category:  GO
Scientific_Category:  GALAXIES & CLUSTERS
             Cycle:    6

Investigators
     PI_name:         Limin Lu
     PI_Institution:  Caltech

          CoI_Name:   Wallace Sargent
   CoI_Institution:   Caltech
           Contact:             ! Y or N (designate at most one contact)

          CoI_Name:   Blair Savage
   CoI_Institution:   University of Wisconsin
           Contact:             ! Y or N (designate at most one contact)

          CoI_Name:   Kenneth Sembach
   CoI_Institution:   Massachusetts Institute of Technology
           Contact:             ! Y or N (designate at most one contact)

          CoI_Name:   Bart Wakker
   CoI_Institution:   University of Wisconsin
           Contact:             ! Y or N (designate at most one contact)


Abstract:                                ! Free format text (please update)
    Observations of damped Ly-alpha\ absorption systems in quasar
    spectra have provided important clues about the chemical
    evolution of galaxies between 0.7<z<4.5. However
    interpretations of these results are complicated by the
    possible presence of dust: it is not clear if the observed
    elemental abundances are intrinsic (ie, direct products of
    nucleosynthesis) or have been modified by dust depletion. The
    above issue can be resolved if we know the intrinsic abundance
    patterns in astrophysical sites that have comparable degrees
    of chemical enrichment as in damped Ly-alpha\ systems but are
    dust-free, since such abundance patterns can serve as a
    reference for recognizing the effects of dust depletion in
    damped Ly-alpha\ systems. Various evidence suggests that the
    high velocity cloud HVC287+22+240 in the direction of the
    Seyfert galaxy NGC3783 may be a good candidate for such a dust
    -free site. Additionally, our previous HST observations
    indicate a Sulphur abundance of 0.15 solar for the HVC,
    comparable to those in damped Ly-alpha\ systems. Here we seek
    a small amount of HST time in order to determine if dust is
    indeed absent in this HVC. If the results indicate there is
    not much dust in the HVC, we will propose to make a detailed
    study of the elemental abundance patterns in the HVC in a
    future HST cycle for the purposes stated above. Regardless of
    whether or not we find dust in the HVC, the current
    observations will provide important clues to the origin and
    nature of the HVC.

Questions                       ! Free format text (please update)

     Observing_Description:
         GHRS Large Science Aperture observations of the bright
         Seyfert galaxy NGC3783 will be made with the G270M grating
         over the wavelength region 2337-2381 Angstrom\ in order to
         measure the Fe II column density from the HVC287+22+240. The
         Fe II lines covered include Lambda2344 and 2374. Since we
         know the S II column density in the HVC from previous
         observations of NGC3783, N(S II)=3.4* 10^14 cm^-2, we can
         predict the strength of the Fe II lines for various Fe/S
         abundance ratios (note that S II and Fe II are the dominant
         ionization stages of S and  Fe  in H I regions so ionization
         corrections are likely to be unimportant). These predictions
         are shown in Figure 3 (previous page). The flux of NGC3783 at
         2350 Angstrom\ is 3* 10^-14 ergs s^-1 cm^-2 AA^-1 based on
         IUE observations, giving a count rate of 0.066 c/s/d. We
         request 4 spacecraft orbits (~ 100 minutes actual integration
         time) in order to achieve S/N=20:1 per diode. With this S/N,
         the combination of the Fe II LambdaLambda2344, 2374 lines
         (which differ in their Lambda f values by a factor of ~ 4)
         will allow us to probe any Fe/S ratio from solar to 1/50
         solar (see Figure 3). This is sufficient to tell if a
         significant amount of dust is present in the HVC, which is
         our main goal here. The S/N ratio and number of spacecraft
         orbits are estimated using the Instrument Handbook for the
         Goddard High Resolution Spectrograph (v6.0, June 1995).
         Standard comb-addition and FP-split will be used to remove
         the effects of fixed pattern noise.  The spectra will be
         sampled with 2 sub-steps per diode (Step Pattern 4). We
         emphasize that the IUE is not capable of obtaining the high
         resolution (FWHM~ 13 km/s), high S/N spectra that we need for
         NGC3783. The GHRS medium resolution is needed in order to
         separate the HVC absorption from Galactic absorption, and to
         assess the effects of line saturation.

   Real_Time_Justification:
         None

         We have already secured observing time on the Australia radio
         telescope to obtain very high resolution (1') 21-cm maps of
         the HVC in the direction of NGC3783. This will allow us to
         more accurately estimate the line-of-sight H I column density
         of the HVC toward NGC3783, therefore improving the accuracy
         of the  absolute metallicity measurements.  Note that
         uncertainties in the N  (H I) have no effect on the analysis
         discussed in this proposal since the dust depletion analysis
         will be based solely on the relative abundance ratio of Fe to
         S.


Calibration_Justification:              ! Move appropriate text from Real_Time_Justification

      Additional_Comments:


Fixed_Targets                           ! Section 5.1
  Target_Number: 1
    Target_Name: NGC3783
Alternate_Names: IRAS1136-374
    Description: Galaxy, Seyfert
       Position: RA=11H 39M 1.662S+/-1",     ! Most common specification format is
                 DEC=-37D 44' 19.79"+/-1",   ! RA=0H 0M 0.00S +/- 0S,
                 PLATE-ID=00JJ               ! DEC=0D 0' 0.0" +/- 0",
                                             ! PLATE-ID=0000
        Equinox: J2000
        RV_or_Z: Z=0.0096
          RA_PM: 0.0                    ! Units are seconds of time per year
         Dec_PM: 0.0                    ! Units are seconds of arc per year
          Epoch:
Annual_Parallax: 0.0
           Flux: V=13.0                 ! Include at least V and B-V
                 f(2350)=3.0+/-0.3 E-14
       Comments: Coordinates from GASP used in pervious HST observations


! This is a template for a single visit containing a single exposure
! Repeat exposure and visit blocks as needed

Visits                                  ! Section 6
      Visit_Number: 1
Visit_Requirements:                     ! Section 7.1

! Uncomment or copy visit level special requirements needed
! Most of these requirements (including ORIENT) will limit scheduling

        ! PCS MODE [Fine | Gyro]
        ! GUIDing TOLerance <angle>
        ! DROP TO GYRO IF NECESSARY [NO REACQuisition]
        ! ORIENTation <angle1> TO <angle2>
        ! ORIENTation <angle1> TO <angle2> FROM <visit>
        ! ORIENTation <angle1> TO <angle2> FROM NOMINAL
        ! SAME ORIENTation AS <visit>
        ! CVZ
        ! PARallel
        ! SCHEDulability <percentage>
        ! AFTER <visit> [BY <time1> [TO <time2>]]
        ! AFTER <date>
        ! BEFORE <date>
        ! BETWEEN <date1> AND <date2>
        ! GROUP <visit-list> WITHIN <time>
        ! PERIOD <time> AND ZERO-PHASE <date>
        ! SEQ <visit-list> WITHIN <time>
        ! ON HOLD [FOR <visit-list>]

  On_Hold_Comments:
    Visit_Comments: target schedulabe only in July and December of 1996 
                    before the 2nd Servicing Mission

     Exposure_Number: 101               
         Target_Name: NGC3783
              Config: HRS
              Opmode: ACQ
            Aperture: 2.0
          Sp_Element: MIRROR-N2
          Wavelength:
 Optional_Parameters: SEARCH-SIZE=3,  ! target position well-known.
                      BRIGHT=RETURN
Number_of_Iterations: 1
   Time_Per_Exposure: 9.0s             ! search-size squared x step-time
Special_Requirements: ONBOARD ACQ FOR 102
            Comments: STEP-TIME=1.0s
                      Expect 4000 count/sec 

     Exposure_Number: 102              
         Target_Name: NGC3783
              Config: HRS
              Opmode: ACCUM
            Aperture: 2.0
          Sp_Element: G270M
          Wavelength: 2359          ! covers 2337-2381 A
 Optional_Parameters: FP-SPLIT=STD,
                      STEP-PATT=4
Number_of_Iterations: 5
   Time_Per_Exposure: 16.32M
Special_Requirements:
            Comments:

     Exposure_Number: 103             
         Target_Name: NGC3783
              Config: HRS
              Opmode: ACQ/PEAKUP
            Aperture: 2.0
          Sp_Element: MIRROR-N2
          Wavelength:
Number_of_Iterations: 1
   Time_Per_Exposure: 51.0s          ! 102 x step-time
Special_Requirements: ONBOARD ACQ FOR 104
            Comments: STEP-TIME=0.5s

     Exposure_Number: 104              
         Target_Name: NGC3783
              Config: HRS
              Opmode: ACCUM
            Aperture: 2.0
          Sp_Element: G270M
          Wavelength: 2359          ! covers 2337-2381 A
 Optional_Parameters: FP-SPLIT=STD,
                      STEP-PATT=4
Number_of_Iterations: 5
   Time_Per_Exposure: 15.36M
Special_Requirements:
            Comments:

! Uncomment or copy exposure level special requirements needed

        ! INTeractive ACQuisition FOR <exp-list>
        ! ONBOARD ACQuisition FOR <exp-list>
        ! SAVE OFFSET <id>
        ! USE OFFSET <id>
        ! POSition TARGet <x-value>,<y-value>
        ! SAME POSition AS <exp>
        ! DO FOR TARGets <targ-list>    ! FGS only
        ! PARallel WITH <exp>
        ! GROUP-FGS <exp-list> WITHIN <time>
        ! SPATIAL SCAN <#> [<exp-list> | SINGLE-EXP ]
        ! RT ANALYSIS [FOR <exp-list>]
        ! REQuires UPLINK
        ! REQuires EPHEMeris CORRection <id>
        ! END ORBIT
        ! EXPAND
        ! LOW-SKY
        ! MAXimum DURation [<time> | <%>]
        ! MINimum DURation [<time> | <%>]
        ! NO SPLIT
        ! PHASE <number1[0,1]> TO <number2[0,1]>
        ! SEQuence <exp-list> NON-INTerruptible
        ! SHADOW


Data_Distribution                       ! Defaults indicated; change if desired

         Medium:        8MM             ! 8MM or 6250BPI or 1600BPI
Blocking_Factor:        10              ! 10 or 1
                                        ! Only astronomers with very old 9-
                                        ! track tape drives should consider
                                        ! a blocking factor of 1

        Ship_To:    the HRS team at     ! STSCI or PI_Address or <free-text>
                    Goddard Space       ! PI Address from Phase I is:
                    Flight Center       !
                                                 !  105-24
                                                 !  Astronomy Department
                                                 !  Pasadena
                                                 !  91125
                                        !
                                        !
       Ship_Via:        UPS             ! UPS (2-day) or OVERNIGHT
                                        ! Overnight shipping done at PI expense

Recipient_Email: hrsdata@cosmos.gsfc.nasa.gov  

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