SED Slit Illumination Function

Principal: psmith
Deputy: jstansberry, dfrayer, nanyao
Data Monkey(s):
Priority: Necessary
Downlink Priority: Normal
Analysis Time: 48 hours
Last Updated:

Objective

To determine the SED-mode slit illumination correction.

Description

The activity will determine the slit illumination by observing several sky positions in a region of high 70 µm background. The SED-mode AOT will be executed with 10 sec integration times at at several telescope positions containing no bright point sources. A median of these observations will be made to average out spatial structure in the background. Each SED AOT provides 4 sky positions. The telescope can be moved to 4 positions using the SED mapping mode. In this case, the moves should be made in the cross-dispersion direction by an amount equal to the length of the slit (about 4.5 arcmin; this is the maximum offset allowed in the SED mapping-mode AOT). Sky regions chosen for 70 µm photometry-mode flat fields should be adequate for this task.

Data Collected

The SED-mode AOT is employed to gather data for several pointings of the telescope. 


The AOR file for Campaign I can be found here
The AOR file for Campaign K can be found here
The AOR file for Campaign O can be found here
The AOR file for Campaign V can be found here

Data Reformatting Requirements

Array Data Desired:

70 µm

Data Reformatting Option:

Special Instructions:

Task Dependencies

Calibration Dependencies

Output and Deliverable Products

A normalized illumination correction for SED will be the product of this IOC task. The task will be executed three times during IOC/SV and the three results will be averaged to construct the illumination correction for the MIPS DAT and the SSC SED pipeline.

Data Analysis

Data analysis for this task is straightforward.
  1. Process the image frames using mips_sloper in the default manner.
  2. Median the 16 blank sky images (IRAF task imcombine, or an equivlent task in IDL).
  3. Divide median image by average pixel value found by the IRAF task "imstatistics" in the median image.
  4. Resulting normalized 32x24 image is the illumination correction for SED mode.

Software Requirements

Actions Following Analysis

The illumination correction supplied to the MIPS DAT and SSC MIPS pipeline for use in processing all SED data.

Failure Modes and Responses

In the event that this task fails to obtain enough sky exposures to median, offset skies from other SED observations can be used to help construct an illumination correction.

Additional Notes

Since the spectrum of the sky is not removed from the illumination function, the flux calibration of SED mode must be modified (re-reduced) whenever the illumination function is modified by the inclusion of additional executions of MIPS-299.