7440( 18) - 12/04/98 11:41  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      7440
                                                       Version: 18
                                                       Check-in Date: 04-Dec-1998
                                                                      11:40:29

1.Proposal Title:
Eclipse Mapping of the Touchstone Binary System YY Gem
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2. Proposal For  3. Cycle
GO               7
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4. Investigators
                                                                                     Contact?
    PI: Jay Bookbinder                    Center for Astrophysics
   CoI: Dr. Steven  Saar                  Smithsonian Astrophysical Observatory         N

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5. Abstract

Solar images clearly demonstrate that its atmosphere consists not of homogeneous,
temperature-stratified layers, but rather of discrete structures on spatial scales
ranging from <100 km to a large fraction of the solar radius, non-uniformly
distributed across the solar disk. Representing stellar emission as due to a
homogeneous atmosphere can yield only an approximate understanding of the global
energy balance. An understanding of the small scale energy balance is required
before we can realistically explore and test the myriad proposed magnetic and non-
magnetic heating mechanisms responsible for the observed emission. We propose to map
the outer atmospheres of the YY Gem system with unprecedented spatial resolution: of
order 0.8\ area (linear scales of about 7000 km) in the transition region and of
order 0.5\ chromosphere (for 10\ by using using the two stars as occulting screens
during the eclipses of this system. Simultaneous observations are planned to
supplement the HST mapping effort; in particular, Doppler imaging will be used to
establish the spatial relationships between spots, plage and the outer atmospheric
emission.
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  Data Distribution

  Paper Products:
  Media:           ELECTRONIC
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:
  Email:
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                                                7440( 18) - 12/04/98 11:41  - [  2]

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   YYGEM        STAR, M V-IV            RA=07H 34M 37.39S +/- 0.1S,      J2000             V = 9.1+/-0.68
                                         DEC=31D 52' 9.0" +/- 0.5"                          B-V = 1.35
    Comments: Coordinates from Hipparcos catalog. Hipparcos plate ID
              number 56.

   Epoch of Position    RA proper motion (seconds of time/yr)    DEC Proper Motion (arcsec/yr)    Annual Parallax (arcsec)
   J2000                -0.0131                                  -0.108                           0.0

                                                7440( 18) - 12/04/98 11:41  - [  3]

Visit: 01
     Visit Priority:      <none>
     Visit Requirements:  PERIOD 0.81428224 D AND ZERO-PHASE JD2425698.356100
     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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10       YYGEM       STIS/C ACQ     F28X50O MIRROR           ACQTYPE=POINT                     1   0.3 S   ONBOARD ACQ FOR 20
                     CD             III
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20       YYGEM       STIS/F TIME-TA 52X0.5  G140L    1425    BUFFER-TIME=4000                  1   27.5 M  NO SPLIT PHASE 0.927 TO
                     UV-MAM G                                                                              0.933 END ORBIT
                     A
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30       YYGEM       STIS/F TIME-TA 52X0.5  G140L    1425    BUFFER-TIME=3000                  1   2000 S  NO SPLIT END ORBIT
                     UV-MAM G
                     A
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                                                7440( 18) - 12/04/98 11:41  - [  4]

Visit: 02
     Visit Priority:      <none>
     Visit Requirements:  AFTER 01 BY 10.915 Orbits TO 11.065 Orbits
     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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10       YYGEM       STIS/C ACQ     F28X50O MIRROR           ACQTYPE=POINT                     1   0.3 S   ONBOARD ACQ FOR 20
                     CD             III
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20       YYGEM       STIS/F TIME-TA 52X0.5  G140L    1425    BUFFER-TIME=3500                  1   31 M    END ORBIT
                     UV-MAM G
                     A
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30       YYGEM       STIS/F TIME-TA 52X0.5  G140L    1425    BUFFER-TIME=3000                  1   2190 S  END ORBIT
                     UV-MAM G
                     A
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                                                7440( 18) - 12/04/98 11:41  - [  5]

Visit: 03
     Visit Priority:      <none>
     Visit Requirements:  AFTER 01 BY 43.875 Orbits TO 44.125 Orbits
     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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10       YYGEM       STIS/C ACQ     F28X50O MIRROR           ACQTYPE=POINT                     1   0.3 S   ONBOARD ACQ FOR 20
                     CD             III
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20       YYGEM       STIS/F TIME-TA 52X0.5  G140L    1425    BUFFER-TIME=3000                  1   31 M    END ORBIT
                     UV-MAM G
                     A
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30       YYGEM       STIS/F TIME-TA 52X0.5  G140L    1425    BUFFER-TIME=3000                  1   2190 S  END ORBIT
                     UV-MAM G
                     A
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                                                7440( 18) - 12/04/98 11:41  - [  6]

            Summary Form for Proposal  7440

  Item                         Used in this proposal
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  Apertures                    F28X50OIII 52X0.5
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  Configurations               STIS/CCD STIS/FUV-MAMA
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  Opmodes                      ACQ TIME-TAG
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  Optional Parameters          ACQTYPE=POINT BUFFER-TIME=4000 BUFFER-TIME=3000 BUFFER-TIME=3500
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  Proposal Category            GO
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  Special Requirements         PERIOD 0.81428224 D AND ZERO-PHASE JD2425698.356100 ONBOARD ACQ FOR 20 NO SPLIT PHASE 0.927 TO
                               0.933 END ORBIT NO SPLIT END ORBIT AFTER 01 BY 10.915 Orbits TO 11.065 Orbits AFTER 01 BY 43.875
                               Orbits TO 44.125 Orbits
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  Spectral Elements            MIRROR G140L
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  Target Names                 YYGEM
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  Wavelengths                  1425
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