Phase II Polarimetry Example

View a formatted APT listing for an example of a NICMOS phase II proposal. In this example, there are three visits. Visits 1 & 2 are for NIC1 and visit 3 is for NIC2 polarimetry observations. R Aqr is used as the example target.

One main concern with polarimetry is saturation of the target. Thus in this example the target is dithered and place it in the center of each quadrant. Patterns are executed separately for each polarizer so that by the time the first pattern is complete, any persistence image from the first pattern position has decayed.

The second concern is the ghosts in the upper two quadrants for NIC1 polarimetry. A target should be placed in the lower two quadrants. However, one way around this problem is to have a second NIC1 visit that is 180 deg from the first visit.

Comments have been added to the visit and exposures.

The following is an RPS2-style Phase II example for Camera 2, which includes a four position dither pattern. A dither stepping of N + 1/2 pixel offsets, where N = 10-50 pixels, is recommended. An image is obtained in each quadrant of the detector. In addition, a pattern orient of 0.11 deg is specified to achieve a 1/4 shift over 128.5 pixels. The Camera 2 scale is ~0.076"/pixel.

Pattern_Data

  Pattern_Number: 1
  Primary_Pattern:
    Pattern_Type: NIC-SPIRAL-DITH
 Pattern_Purpose: DITHER
Number_Of_Points: 4
   Point_Spacing: 9.766
Coordinate_Frame: POS-TARG
  Pattern_Orient: 0.11
  Center_Pattern: 


     Exposure_Number: 10
         Target_Name: R-Mon
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2-FIX
          Sp_Element: POL0L
          Wavelength:
 Optional_Parameters: SAMP-SEQ=STEP16,NSAMP=12
Number_of_Iterations: 2
   Time_Per_Exposure: DEF
Special_Requirements:                   
POS TARG -4.902,-4.902
                      PATTERN 1 10-30
            Comments: exp=95.945 sec


     Exposure_Number: 20
         Target_Name: R-Mon
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2-FIX
          Sp_Element: POL120L
          Wavelength:
 Optional_Parameters: SAMP-SEQ=STEP16,NSAMP=12
Number_of_Iterations: 2
   Time_Per_Exposure: DEF
Special_Requirements:
                      POS TARG -4.902,-4.902
            Comments: exp=95.945 sec


     Exposure_Number: 30
         Target_Name: R-Mon
              Config: NIC2
              Opmode: MULTIACCUM
            Aperture: NIC2-FIX
          Sp_Element: POL240L
          Wavelength:
 Optional_Parameters: SAMP-SEQ=STEP16,NSAMP=12
Number_of_Iterations: 2
   Time_Per_Exposure: DEF
Special_Requirements:
                      POS TARG -4.902,-4.902
            Comments: exp=95.945 sec