160 µm PSF Characterization

Principal: Karl Stapelfeldt
Deputy: Dean Hines, Jane Morisson
Data Monkey(s):
Priority: Desired
Downlink Priority: Normal
Analysis Time: One month
Last Updated:

Objective

Measure the field dependence of the MIPS 160 µm point spread function, using a blue astronomical source.

Description

Each source will be observed at 4 positions spread along the length of the 160 micron detector FOV. Positions 1 and 3 will match exactly the positions of the source in the standard photometry AOT. Positions 2 and 4 will be at non-standard positions near the center and right parts of the FOV. AT EACH OF THESE 4 POSITIONS, WE OBSERVE THE STAR 20 TIMES over an 5x4 grid stepped by 1/4 pixel. A cluster target is used, with 4 subpixel steps along the long axis of the detector array, and 5 subpixel positions perpendicular to it.

Data Collected

This will be standard MIPS photometry data for 160 microns. Two cycles of 3 sec exposures will be taken at each of the 20 subpixel sampling positions, at each of the four field of view positions. Two AORs are used to get the data.

Data Reformatting Requirements

Array Data Desired:

160 µm

Data Reformatting Option:

SPECIAL

Special Instructions:
Separate extended fits file for each of the 20 positions of the cluster target.
Task Dependencies

912
248
112

Calibration Dependencies

Good flat fields and distortion corrections are essential

Output and Deliverable Products
MIPS data will be reduced by the task lead, and made available to a consulting optical expert. Deliverables will be sets of Zernicke polynomial coefficients for different positions in the 160 µm field of view.
Data Analysis
Optical consultant will fit the PSF images with models to derive field-dependent aberrations in the 160 µm optical train.
Software Requirements

MIPS DAT to remove detector response from data
SIRTF TinyTIM to model the PSF shape as a function of aberrations
IDL tools to iterate models PSF to achieve best fit

Actions Following Analysis
Written report will be generated on PSF properties of the camera. Results to be supplied to SSC and observer teams concerned with accurate source extractions.
Failure Modes and Responses
Stable and repeatable telescope pointing is needed to properly subsample the PSF. Program might have to be repeated if significant pointing drifts take place.
Additional Notes
Consulting agreement being finalized with John Krist (STScI) to serve as optical data analyst