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Phase II Example: NICMOS Polarimetry

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