SED Throughput Dependence on CSMM Position

Principal: psmith
Deputy: jstansberry, dfrayer, nanyao
Data Monkey(s):
Priority: Desired
Downlink Priority: Normal
Analysis Time: 72 hours
Last Updated:

Objective

Determine the relative throughput at the five possible scan mirror positions in SED mode.

Description

For this test, we need to point the telescope at a region of sky that is relatively bright and uniform at 70um. Using stim flashes for calibration, we observe the sky at the nominal CSMM relpos position. We then offset to +1 arcmin using relpos, but also issue a PCS command to compensate for that move and put the same patch of sky onto the SED slit. Again measure the brightness using stim flashes to track changes in the instrumental response. Repeat for positions +2 and +3 arcmin. The brightness at each of these four CSMM positions is determined to see if there is a CSMM angle-dependent throughput gradient.

Data Collected

The target sky position can be any relatively uniform background that is bright. This IOC activity is not greatly affected by by the choice of sky position for the slit as long as the telescope can be offset accurately (within a few arcsec) to compensate for the required changes in the CSMM position. For the current launch date of August 23, 2003, the recommended flat field target is "zodi_13a" (RA=08h06m28.72s, DEC=+25d22m35.0s).

Data Reformatting Requirements

Array Data Desired:

70 µm

Data Reformatting Option:

Special Instructions:

Task Dependencies

Calibration Dependencies

Output and Deliverable Products

Determination of the existence of a sensitivity gradient as a function of scan mirror position. If no gradient or significant variations detected, no further action needs to be taken. If a gradient is detected, the nominal scan mirror position for observations will be determined along with scaling factors for each of the sky offset positions.

Data Analysis

Ratios of DCEs from the various CSMM offset positions will be taken to determine if significant differences exist in the overall throughput of the instrument as a function of CSMM position. If differences are found, the offset position with the best throughput will be identified. In addition, scaling factors for the other offset positions relative to the position with the highest throughput will be derived so that the throughput variations can be included in the processing of SED-mode data.

Software Requirements

Actions Following Analysis

If no gradient or significant variations are detected, no further action needs to be taken. If a gradient is detected, the nominal scan mirror position for observations will be delivered along with scaling factors for each of the sky offset positions. In this case, it may also be desirable to repeat this task on another patch of sky to see if the experiment (and scaling factors) are repeatable.

Failure Modes and Responses

Additional Notes