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Hubble Space Telescope
NICMOS Proposing Example - 2

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!  | PED OUTPUT PRODUCT |
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!
!  /data/antares1/nicmos/1001.prop
!  Generated by PREPROCESSOR, version 6.6b
!  Date: Mon Dec 02 10:46:59 EST 1996

Proposal_Information
              Title: NICMOS Imaging of Nearby Galaxies
  Proposal_Category: GO
Scientific_Category: GALAXIES
              Cycle: 7


Investigators

            PI_Name: Joan Smith
     PI_Institution: University 1


           CoI_Name: John Brown
    CoI_Institution: University 2
            Contact: 


Abstract:
Various uses of the NICMOS Patterns. Dithering. PATTERNS versus POS TARG. 
Observations in the Thermal Background regime.

Questions


    Observing_Description:

The NICMOS PATTERNs are optional parameters which allow observers to
specify in a single instruction line a series of dithered exposures
and/or a chopping sequence between target and background (see the
NICMOS Instrument Manual for more details). The PATTERNs are a concise
version of POS TARG, since an entire set of pointings is specified in
one exposure log. However, there may be situation in which the use of 
POS TARG is still convenient (see Visit 3 below).

The proposers want to observe three different targets (both extended;
e.g.  nearby galaxies), with different goals in mind.  The proposal is
divided in three separated visits.

VISIT 1: (mapping and spatial sampling) H-band imaging of stars in a
nearby galaxy, using NIC2 and the F160W filter. The observers want to
cover an extended region (about 30"x30"), while sampling each position
at more than one location on the detector for photometric accuracy.
For this purpose, the pattern SPIRAL-DITH-CHOP is selected, with a
chop throw (0".75) smaller than the dither step (15"). Typical
exposure times are of the order of 500 seconds per position. The
MULTIACCUM sequence STEP256 with 12 samples (NSAMP=12, corresponding
to an integration time of 512 seconds) is selected to ensure
sufficient information for cosmic ray rejection, and enough dynamical
range in the images.

VISIT 2: (dithering+chopping) Imaging of an extended object (e.g. nearby
galaxy) at 2.2 micron (continuum) and in the light of the molecular
hydrogen emission at 2.12 micron. The observers want to use the Camera
with the largest FOV: NIC3 with the F222M and F212N filters is
selected. To recover some of the resolution, dithering techniques are
used. The SPIRAL-DITH-CHOP pattern is used with sub-pixel dither step
(2".1 = 10.5 pixels in NIC3). The chop throw is chosen to be 60", to
obtain background images for removing the telescope thermal
emission. The default OFFSET parameter (SAM) is used, implying that
the background images may be obtained on gyros if the offset from the
target cannot be supported by small angle maneuvers. Fluctuations on
the thermal background constrain the integration times on each
position to about 5 minutes before a chop to the background is
required (this constraint will be subject to on-orbit
verification). The integration times need to be shorter in the F222M
filter, because the counts from the thermal background are high enough
to saturate the filter in less than 300 seconds; the exposures are
background dominated after about 1 second of integration.  For this
filter, two ACCUM exposures of 150 seconds each are given with NREAD=1
(the advantage in readout noise reduction provided by NREAD=9 is not
needed here since the exposures become quickly beckground dominated);
the double exposure will help with cosmic ray removal.  The surface
brightness of the galaxy in the molecular hydrogen emission shows
large variations, and for the F212N filter the observers decide to use
the MULTIACCUM sequence STEP256 with NSAMP=11 (corresponding to a
maximum exposure of 256 seconds) to get different level of exposure
and to remove cosmic rays.  The F222M filter is used as continuum for
the F212N filter.

VISIT 3: (multifilter imaging of two separate regions in the extended
target). The observers want to image two regions separated by 20
arcseconds, using NIC2 and two filters, F110W and F160W. The use of
POS TARG, rather than a dithering PATTERN may be the best solution.
The PATTERNs are entirely executed for ONE filter at the time. In this
case, a pattern would observe both regions in F110W, then switch to
the F160W and observe the two regions in the second filter. The
telescope would thus go three times back and forth between the two
regions, using valuable orbit time for the movements. POS TARG,
instead, allow the user to specify individual telescope moves. Since
each POS TARG requires a new exposure log, the advantage is that there
is no limitation in the number of filters which can be specifies at
each POS TARG position. Therefore, the (often time-consuming) number
of telescope moves is minimized. The disadvantage is a more cumbersome
Visit description.  
IMPORTANT: If the specified POS TARG implies a telescope move OUTSIDE
the Field of View of the Camera, a warning message will be issued 
by RPS2.  Observers may ignore the message, and are encouraged to put
a comment at the exposure level explaining that they are aware of the
problem, and that the specified POS TARG is exactly what they want.


  Real_Time_Justification:


Calibration_Justification:


      Additional_Comments:



Fixed_Targets

  Target_Number: 1
    Target_Name: NGC1111
Alternate_Names: Nice Galaxy 1
    Description: GALAXY
       Position: RA=13H 50M 49.40S +/- 0.02S,DEC=52D 20' 58.0" +/- 0.7"
        Equinox: J2000
        RV_or_Z: 
          RA_PM: 0.0
         Dec_PM: 0.0
          Epoch: 
Annual_Parallax: 0.0
           Flux: 
                F(1.60)=0.00
       Comments: The value of the flux is in units of Jy, at 1.6 microns

  Target_Number: 2
    Target_Name: NGC2222
Alternate_Names: Nice Galaxy 2
    Description: GALAXY
       Position: RA=14H 36M 50.40S +/- 0.02S,DEC=42D 30' 58.0" +/- 0.7"
        Equinox: J2000
        RV_or_Z: 
          RA_PM: 0.0
         Dec_PM: 0.0
          Epoch: 
Annual_Parallax: 0.0
           Flux: 
                F(2.2)=0.00
       Comments: The value of the flux is in units of Jy, at 2.2 microns


  Target_Number: 3
    Target_Name: NGC3333
Alternate_Names: Nice Galaxy 3
    Description: GALAXY
       Position: RA=11H 12M 30.40S +/- 0.02S,DEC=55D 34' 58.0" +/- 0.7"
        Equinox: J2000
        RV_or_Z: 
          RA_PM: 0.0
         Dec_PM: 0.0
          Epoch: 
Annual_Parallax: 0.0
           Flux: 
                F(1.9)=0.00
       Comments: The value of the flux is in units of Jy, at 1.9 microns


Solar_System_Targets


Generic_Targets


Scan_Data


Visits

      Visit_Number: 01
Visit_Requirements: 
  On_Hold_Comments: 
    Visit_Comments: This is the mapping and spatial sampling visit

     Exposure_Number: 1
         Target_Name: NGC1111
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2
          Sp_Element: F160W
          Wavelength: 
 Optional_Parameters: PATTERN=SPIRAL-DITH-CHOP,NUM-POS=8,DITH-SIZE=15,CHOP-SIZE=0.75,SAMP-SEQ=STEP256,NSAMP=12
Number_of_Iterations: 1
   Time_Per_Exposure: DEF
Special_Requirements: 
            Comments: 

      Visit_Number: 02
Visit_Requirements: 
  On_Hold_Comments: 
    Visit_Comments: This is the dithering+chopping visit

     Exposure_Number: 1
         Target_Name: NGC2222
              Config: NIC3
              Opmode: ACCUM
            Aperture: NIC3
          Sp_Element: F222M
          Wavelength: 
 Optional_Parameters: PATTERN=SPIRAL-DITH-CHOP,NUM-POS=8,DITH-SIZE=2.1,CHOP-SIZE=60.0
Number_of_Iterations: 2
   Time_Per_Exposure: 150S
Special_Requirements: 
            Comments: 

     Exposure_Number: 2
         Target_Name: NGC2222
              Config: NIC3
              Opmode: MULTIACCUM
            Aperture: NIC3
          Sp_Element: F212N
          Wavelength: 
 Optional_Parameters: PATTERN=SPIRAL-DITH-CHOP,NUM-POS=8,DITH-SIZE=2.1,CHOP-SIZE=60.0,SAMP-SEQ=STEP256,NSAMP=11
Number_of_Iterations: 1
   Time_Per_Exposure: DEF
Special_Requirements: 
            Comments: 


      Visit_Number: 03
Visit_Requirements: 
  On_Hold_Comments: 
    Visit_Comments: This is the POS TARG visit

     Exposure_Number: 1
         Target_Name: NGC3333
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2
          Sp_Element: F110W
          Wavelength: 
 Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=11
Number_of_Iterations: 1
   Time_Per_Exposure: DEF
Special_Requirements: 
            Comments: This is the F110W exposure on the first region

     Exposure_Number: 2
         Target_Name: NGC3333
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2
          Sp_Element: F160W
          Wavelength: 
 Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=11
Number_of_Iterations: 1
   Time_Per_Exposure: DEF
Special_Requirements: 
            Comments: This is the F160W exposure on the first region

     Exposure_Number: 3
         Target_Name: NGC3333
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2
          Sp_Element: F110W
          Wavelength: 
 Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=11
Number_of_Iterations: 1
   Time_Per_Exposure: DEF
Special_Requirements: POS TARG 20, 0
            Comments: This is the F110W exposure on the second region

     Exposure_Number: 4
         Target_Name: NGC3333
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2
          Sp_Element: F160W
          Wavelength: 
 Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=11
Number_of_Iterations: 1
   Time_Per_Exposure: DEF
Special_Requirements: POS TARG 20, 0
            Comments: This is the F160W exposure on the second region


Data_Distribution         ! Defaults indicated; change if desired

         Medium: 8MM
        Ship_To: PI_Address
Recipient_Email: 

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