10843(  5) - 05/12/06 06:48  - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 10843

Version: 5    Check-in Time: 12-May-2006 10:47:48       STScI Edit Number: <none>

Title
Deep Imaging of Extremely Metal-Poor Galaxies
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Type             Cycle     Parallel Pointing Tolerance
GO               15        <none>
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Investigators
                                                                                     Contact?
    PI: Dr. Michael Corbin                Arizona State University
   CoI: Dr. David Burstein                Arizona State University                      N
   CoI: Dr. Rolf A. Jansen                Arizona State University                      N

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Abstract

Conflicting evidence exists regarding whether the most metal-poor and actively star-
forming galaxies in the local universe such as I Zw 18 contain evolved stars. We
propose to help settle this issue by obtaining deep ACS/HRC U, narrow-V, I, and H-
alpha images of nine nearby (z < 0.01) extremely metal-poor (12 + O/H < 7.65)
galaxies selected from the Sloan Digital Sky Survey. These objects are only
marginally resolved from the ground and appear uniformly blue, strongly motivating
HST imaging. The continuum images will establish: 1.) If underlying populations of
evolved stars are present, by revealing the objects' colors on scales ~10 pc, and
2.) The presence of any faint tidal features, dust lanes, and globular or super star
clusters, all of which constrain the objects' evolutionary states. The H-alpha
images, in combination with ground-based echelle spectroscopy, will reveal 1.)
Whether the objects are producing "superwinds" that are depleting them of their
metals; ground-based images of some of them indeed show large halos of ionized gas,
and 2.) The correspondence of their nebular and stellar emission on scales of a few
parsecs, which is important for understanding the "feedback" process by which
supernovae and stellar winds regulate star formation. One of the sample objects,
CGCG 269-049, lies only ~2 Mpc away, allowing the detection of individual red giant
stars in it if any are present. We have recently obtained Spitzer images and spectra
of this galaxy to determine its dust content and star formation history, which will
complement the proposed HST observations. [NOTE: THIS PROPOSAL WAS REDUCED TO FIVE
ORBITS, AND ONLY ONE OF THE ORIGINAL TARGETS, CGCG 269-049, AFTER THE PHASE I
REVIEW]
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  Observations Description
  ------------------------

     We have been awarded five orbits to image the galaxy CGCG 269-049 using the
     Advanced Camera for Surveys. We will image the galaxy in the broad-band filters
     F330W, F550M, and F814W with the High Resolution Channel, and with the F658N
     filter using the Wide Field Channel. This is because the H-alpha emission of
     the galaxy may extend further than the HRC field of view.

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


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


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

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                                                10843(  5) - 05/12/06 06:48  - [  3]

TARGET LIST    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   CGCG269-049  GALAXY, DWARF COMPACT,  RA=12H15M46.8900S +/- 0.1",      J2000             Sloan g = 15.87
                 STARBURST               DEC=+52D23'13.90" +/- 0.1"
    Reference Frame: ICRS

                                                10843(  5) - 05/12/06 06:48  - [  4]

Patterns
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Pattern_Number: 1

                    Primary_Pattern                   Secondary_Pattern
Pattern_Type        ACS-HRC-DITHER-LINE
Pattern_Purpose     DITHER
Number_Of_Points    2
Point_Spacing       0.198
Line_Spacing        <none>
Coordinate_Frame    POS-TARG
Pattern_Orient      44.28
Angle_Between_Sides <none>
Center_Pattern      NO

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Pattern_Number: 2

                    Primary_Pattern                   Secondary_Pattern
Pattern_Type        ACS-WFC-DITHER-LINE
Pattern_Purpose     DITHER
Number_Of_Points    2
Point_Spacing       3.011
Line_Spacing        <none>
Coordinate_Frame    POS-TARG
Pattern_Orient      85.28
Angle_Between_Sides <none>
Center_Pattern      NO

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                                                10843(  5) - 05/12/06 06:48  - [  5]

Visit: 01
     Visit Priority:      <none>
     Visit Requirements:  <none>
     On Hold Comments:    <none>
     Additional Comments: <none>


Exposures
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Exp |   Target  | Instr  | Oper. | Aper    |Spectral|Central|           Optional           |Num|   Time   |       Special
Num |    Name   | Config | Mode  | or FOV  |Element |Waveln.|          Parameters          |Exp|          |     Requirements
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1    CGCG269-049 ACS/HRC  ACCUM   HRC       F330W                                           1   1000 S     PATTERN 1 1-3
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2    CGCG269-049 ACS/HRC  ACCUM   HRC       F550M                                           1   3160 S
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3    CGCG269-049 ACS/HRC  ACCUM   HRC       F814W                                           1   1060 S
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4    CGCG269-049 ACS/WFC  ACCUM   WFC       F658N                                           1   500 S      PATTERN 2 4
                                                                                                see below
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Sub Exposures
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Target             | Exp |Instr   | Oper. |  Aper  |Spectral|Cent.|Primary     |Secondary   |Iteration |CR-SPLIT  |Orbit  |Duration
Name               | Num |Config  | Mode  | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num       |Num       |Number |
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CGCG269-049         1     ACS/HRC  ACCUM   HRC      F330W          1            none         none       1          1       N/A
CGCG269-049         1     ACS/HRC  ACCUM   HRC      F330W          1            none         none       2          1       N/A
CGCG269-049         1     ACS/HRC  ACCUM   HRC      F330W          2            none         none       1          3       N/A
CGCG269-049         1     ACS/HRC  ACCUM   HRC      F330W          2            none         none       2          3       N/A
CGCG269-049         2     ACS/HRC  ACCUM   HRC      F550M          1            none         none       1          1       N/A
CGCG269-049         2     ACS/HRC  ACCUM   HRC      F550M          1            none         none       2          2       N/A
CGCG269-049         2     ACS/HRC  ACCUM   HRC      F550M          2            none         none       1          3       N/A
CGCG269-049         2     ACS/HRC  ACCUM   HRC      F550M          2            none         none       2          4       N/A
CGCG269-049         3     ACS/HRC  ACCUM   HRC      F814W          1            none         none       1          2       N/A
CGCG269-049         3     ACS/HRC  ACCUM   HRC      F814W          1            none         none       2          2       N/A
CGCG269-049         3     ACS/HRC  ACCUM   HRC      F814W          2            none         none       1          4       N/A
CGCG269-049         3     ACS/HRC  ACCUM   HRC      F814W          2            none         none       2          4       N/A
CGCG269-049         4     ACS/WFC  ACCUM   WFC      F658N          1            none         none       1          5       548.0 S
CGCG269-049         4     ACS/WFC  ACCUM   WFC      F658N          1            none         none       2          5       548.0 S
CGCG269-049         4     ACS/WFC  ACCUM   WFC      F658N          2            none         none       1          5       548.0 S
CGCG269-049         4     ACS/WFC  ACCUM   WFC      F658N          2            none         none       2          5       548.0 S
                                                10843(  5) - 05/12/06 06:48  - [  6]

            Summary Form for Proposal  10843

  Item                         Used in this proposal
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  Apertures                    HRC WFC
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  Configurations               ACS/HRC ACS/WFC
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  Opmodes                      ACCUM
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  Special Requirements         PATTERN 1 1-3; PATTERN 2 4;
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  Spectral Elements            F330W F550M F814W F658N
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  Target Names                 CGCG269-049
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