5949(  5) - 11/22/95 13:25  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      5949
                                                       Version: 5
                                                       Check-in Date: **********

1.Proposal Title:
High Resolution Imaging of Galaxies Responsible for QSO Lyman-alpha Absorption
Sytems
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2. Scientific Category   3. Proposal For  4. Cycle
Quasars                     GO               5
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5. Investigators
                                                                                     Contact?
    PI: Kenneth Lanzetta                  State University of New York at Stony
                                          Brook
   CoI: David V. Bowen                    Space Telescope Science Institute             N
   CoI: John K. Webb                      University of New South Wales                 N
   CoI: J. Chris Blades                   Space Telescope Science Institute             N

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6. Abstract

Using a combination of archived and published FOS QSO spectra and ground-based low
resolution multi-slit spectroscopy, we have been pursuing a program to directly
identify the objects responsible for low or intermediate redshift QSO absorption.
Our results suggest that a significant fraction of intermediate redshift Lyman alpha
absorbers arise in very extended gaseous regions around galaxies.  However, with
existing gound-based images we are unable to clearly resolve the galaxies we
identify.  Thus we have no information as to how the QSO absorption characteristics
depend on galaxy type, morphology, orientation or inclination to the line of sight
to the background QSO.  We propose here to obtain high resolution WFPC2 images of
carefully selected fields centred on HST target QSOs.  We will then have the
exciting possiblity of carrying out detailed studies of specific galaxies which are
already known to be associated with specific QSO absorption systems.  For the first
time, it will be possible to learn how the QSO absorption characteristics relate to
galaxy type, what the gaseous morphology of those galaxies is, and how the
inclination and orientation of the galaxy with respect to the QSO line of sight
affect the absorption properties.
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                                                5949(  5) - 11/22/95 13:25  - [  2]

  Observations Description
  ------------------------

     Exposure times for individual F702W frames are calculated to allow accurate
     morphological classification of faint galaxies and to prevent excessive
     saturation of the QSOs. The QSOs of our sample have <R> ~ 16.7 and lie at a z ~
     0.5.  We have simulated the observed QSO profile with WFPC2 using an r^1/4
     intensity profile with scale length of 1.5 h^-1 kpc (Hutchings et al. 1994).
     Assuming a gain of 7 e^- DN^-1 and a readout noise of 5 e^- rms, we find that
     the central pixel is saturated after ~ 660 secs, but that adjacent pixels
     remain unsaturated.  The Ly-alpha absorbing galaxies have a limiting magnitude
     of R ~ 21.0, and lie at a median z of ~ 0.3.  Galaxy scale lengths of 2.0 h^-1
     kpc then correspond to 0.7 arcsec.  We have simulated WFPC2 images of galaxies
     with exponential disks and r^1/4 bulges in Figure 2a. Face-on and edge-on disks
     are easily recognized from elliptical galaxies, but galaxies with axial ratios
     b/a ~ 0.5 are the hardest to distinguish.  We have therefore calculated surface
     brightness profiles for both models with b/a ~ 0.5 (Fig 2b).  In a single
     orbit, we obtain 3 * 600 sec frames, and in one to two orbits we achieve a S/N
     sufficient to differentiate between the two models.  The same simulations show
     that the magnitude limit for these observations is r ~ 24 at the 2-3 sigma
     level.  This magnitude corresponds to M_B = -14.8 for a star-forming Im galaxy
     (Coleman, Wu & Weedman 1980).  Hence we will easily be able to detect LMC/SMC
     type companions to the Ly-alpha absorbers or other star-forming galaxies close
     to the line of sight.  We will devote one orbit to each of two fields for which
     the galaxies of interest occur at lower redshifts (z ~< 0.2) and two orbits to
     each of two fields for which the galaxies of interest occur at higher redshifts
     (z ~< 0.4).

  Real Time Justification
  -----------------------

     Not applicable.

  Calibration Justification
  -------------------------

     Not applicable.

  Additional Comments
  -------------------

     Not applicable.
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  Data Distribution

  Media:           8MM
  Blocking Factor: 10
  Ship To:         PI_address
  Ship Via:        UPS
  Email:                                                              ,
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                                                5949(  5) - 11/22/95 13:25  - [  3]

TARGET LIST    a) Fixed Targets
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Tar|   Target   |         Target        |            Target              |Coord   | Radial |             Flux data
No |    Name    |       Description     |           Position             |Eqnx    |  Vel.  |
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1   FIELD-035128 GALAXY,QSO              RA = 03H 49M 08.12S +/- 0.07S,   1950     Z =      V = 16.22 +/- 0.1
    -142909                              DEC = -14D 37' 47.0" +/- 1.0"             0.616    B-V  = 0.33 +/- 0.1
    Comments: POINTING POSITION IS 20 ARCSEC WEST AND 20 ARCSEC
              NORTH OF THE QSO 0349-1438

2   FIELD-040525 GALAXY,QSO              RA = 04H 05M 25.40S +/- 0.07S,   1950     Z =      V = 14.82 +/- 0.1
    -121140                              DEC = -12D 19' 36.8" +/- 1.0"             0.574    B-V  = 0.18 +/- 0.1
    Comments: POINTING POSITION IS 30 ARCSEC WEST AND 5 ARCSEC SOUTH
              OF THE QSO 0405-1219

3   FIELD-       GALAXY,QSO              RA = 08H 50M 14.34S +/- 0.07S,   1950     Z =      V = 16.62 +/- 0.1
    085334+43490                         DEC = +44D 00' 24.0" +/- 1.0"             0.513
    6
    Comments: POINTING POSITION IS 8 ARCSEC EAST AND 5 ARCSEC SOUTH
              OF THE QSO 0850+4400

4   FIELD-       GALAXY,QSO              RA = 10H 01M 09.0S +/- 0.07S,    1950     Z =      V = 15.5 +/- 0.1
    100400+28551                         DEC = +29D 09' 50.0" +/- 1.0"             0.329    B-V  = 0.12 +/- 0.1
    6
    Comments: POINTING POSITION IS TOWARD THE QSO 1001+2910

5   FIELD-       GALAXY,QSO              RA = 13H 54M 43.50S +/- 0.07S,   1950     Z =      V = 16.30 +/- 0.1
    135704+19190                         DEC = +19D 33' 38.9" +/- 1.0"             0.719    B-V  = 0.18 +/- 0.1
    7
    Comments: POINTING POSITION IS 20 ARCSEC EAST AND 5 ARCSEC SOUTH
              OF THE QSO 1354+1933

6   FIELD-       GALAXY,QSO              RA = 17H 04M 04.29S +/- 0.07S,   1950     Z =      V = 15.28 +/- 0.1
    170442+60442                         DEC = +60D 48' 29.1" +/- 1.0"             0.371    B-V  = 0.13 +/- 0.1
    8
    Comments: POINTING POSITION IS 6 ARCSEC EAST AND 2 ARCSEC SOUTH
              OF THE QSO 1704+6048

                                                5949(  5) - 11/22/95 13:25  - [  4]

Visit: 01
     Visit Requirements:  ORIENT 270.0D TO 345.0D
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exposure|   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |               Special
 Number |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |             Requirements
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1        FIELD-      WFPC2  IMAGE   WFALL-  F702W            ATD-GAIN = 7,   3   800S
         035128-                    FIX                      CLOCKS = YES,
         142909                                              CR-SPLIT = NO
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                                                5949(  5) - 11/22/95 13:25  - [  5]

Visit: 02
     Visit Requirements:  ORIENT 35.0D TO 50.0D
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exposure|   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |               Special
 Number |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |             Requirements
------------------------------------------------------------------------------------------------------------------------------------
1        FIELD-      WFPC2  IMAGE   WFALL-  F702W            ATD-GAIN = 7,   3   800S
         040525-                    FIX                      CLOCKS = YES,
         121140                                              CR-SPLIT = NO
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                                                5949(  5) - 11/22/95 13:25  - [  6]

Visit: 03
     Visit Requirements:  ORIENT 150.0D TO 190.0D
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exposure|   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |               Special
 Number |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |             Requirements
------------------------------------------------------------------------------------------------------------------------------------
1        FIELD-      WFPC2  IMAGE   WFALL-  F702W            ATD-GAIN = 7,   3   800S
         085334+4349                FIX                      CLOCKS = YES,
         06                                                  CR-SPLIT = NO
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                                                5949(  5) - 11/22/95 13:25  - [  7]

Visit: 04
     Visit Requirements:  ORIENT 255.0D TO 285.0D
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exposure|   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |               Special
 Number |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |             Requirements
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1        FIELD-      WFPC2  IMAGE   WFALL-  F702W            ATD-GAIN = 7,   3   800S
         100400+2855                FIX                      CLOCKS = YES,
         16                                                  CR-SPLIT = NO
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                                                5949(  5) - 11/22/95 13:25  - [  8]

Visit: 05
     Visit Requirements:  ORIENT 80.0D TO 125.0D
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exposure|   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |               Special
 Number |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |             Requirements
------------------------------------------------------------------------------------------------------------------------------------
1        FIELD-      WFPC2  IMAGE   WFALL-  F702W            ATD-GAIN = 7,   3   800S
         135704+1919                FIX                      CLOCKS = YES,
         07                                                  CR-SPLIT = NO
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                                                5949(  5) - 11/22/95 13:25  - [  9]

Visit: 06
     Visit Requirements:  ORIENT 350.0D TO 30.0D
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exposure|   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |               Special
 Number |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |             Requirements
------------------------------------------------------------------------------------------------------------------------------------
1        FIELD-      WFPC2  IMAGE   WFALL-  F702W            ATD-GAIN = 7,   4   600S
         170442+6044                FIX                      CLOCKS = YES,
         28                                                  CR-SPLIT = NO
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                                                5949(  5) - 11/22/95 13:25  - [ 10]

            Summary Form for Proposal  5949

  Item                         Used in this proposal
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  Configurations               WFPC2
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  Opmodes                      IMAGE
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  Optional Parameters          ATD-GAIN = 7 CLOCKS = YES CR-SPLIT = NO
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  Proposal Category            GO
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  Scientific Category          Quasars
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  Special Requirements         ORIENT 270.0D TO 345.0D ORIENT 35.0D TO 50.0D ORIENT 150.0D TO 190.0D ORIENT 255.0D TO 285.0D
                               ORIENT 80.0D TO 125.0D ORIENT 350.0D TO 30.0D
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  Spectral Elements            F702W
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  Target Names                 FIELD-035128-142909 FIELD-040525-121140 FIELD-085334+434906 FIELD-100400+285516 FIELD-135704+191907
                               FIELD-170442+604428
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