Electronic Nonlinearities Verification

Principal: Karl Gordon
Deputy: James Muzerolle
Data Monkey(s):
Priority: Normal
Downlink Priority: Normal
Analysis Time: 72 hours
Last Updated:

Objective

This task will verify and refine the electronic nonlinearities correction for all three arrays. The data obtained for this purpose will also be used to assess the flight 70 and 160 µm noise levels and 24, 70, and 160 µm cosmic ray behavior.

Description

All three MIPS arrays display nonlinearites due to their electronics. These nonlinearities will be well characterized in pre-launch tests and this task will verify they have not changed.

Extensive pre-launch tests will be used to construct the electronic linearity corrections for all three arrays. This task will verify that these corrections are still the appropriate ones to use.

Outline of the Task:
**All the data will be 10 MIPS second exposures**
  1. 24µm part
    • Point to the 24um dark position
    • Turn on the 24um stim to a level which (on average) fill 5% well in 10s
    • Take a 50 10s *RAW* DCEs.
    • Turn on the 24um stim to a level which (on average) fill 7/8 well in 10s
    • Take a 50 10s *RAW* DCEs.
  2. 70 & 160 µm part
    • Turn on the 70um flash stim to a level which (on average) fill 1/4 well in 10s
    • Turn on the 160um flash stim to a level which (on average) fill 1/4 well in 10s
    • Take a 50 10s DCEs on both the 70 and 160um arrays.
    • Turn on the 70um flash stim to a level which (on average) fill 1/2 well in 10s
    • Turn on the 160um flash stim to a level which (on average) fill 1/2 well in 10s
    • Take a 50 10s DCEs on both the 70 and 160um arrays.
    • Turn the 70um flash stim to a level which (on average) fills the well in 10s
    • Turn the 160um flash stim to a level which (on average) fills the well in 10s
    • Take a 50 10s DCEs on both the 70 and 160um arrays.
    • Turn the 70um flash stim to a level which (on average) fill 1 1/2 the well in 10s
    • Turn the 160um flash stim to a level which (on average) fill 1 1/2 the well in 10s
    • Take a 50 10s DCEs on both the 70 and 160um arrays.

Data Collected

All the datasets generated for this taks will be composed of 50, 10 second RAW DCEs (mips_ier180.exp).

Data Reformatting Requirements

Array Data Desired:

All Arrays

Data Reformatting Option:

Special Instructions:
Each 50 DCE dataset should be packed into a single FITS file with extensions. This would generate two such FITS files for the 24µm part of this task. This would generate eight such FITS files (4 for each array) for the 70 and 160 µm part of this task.

Task Dependencies

Calibration Dependencies

Output and Deliverable Products

The main output of this task is to verify that the ground-based electronic nonlinearity corrections are valid to use for in-orbit data. The ground-based corrections have been generated from much more extensive observations.

Secondary outputs from this task are in-orbit characterizations of the Ge array noise properties and response of the Ge detectors to cosmic rays.

Data Analysis

All the datasets will be run through mips_sloper using the ground-based electronic nonliearity correction files. The resulting corrected ramps will be examined using xsloper_view.pro to visually assess the linearity of the ramps. More quantitative checks will be done with the create_lincor.pro programs to directly compare the linearity of many ramps for the same pixel.

The in-orbit Ge array noise model will be assessed by using the output of create_lincor.pro (when it is run on only the datasets created as part of this task) is the program check_noise.pro. The check_noise.pro program fits an empirical function to the measured noise as a function of measured DN.

The in-orbit behavior of the cosmic rays will be assessed using the output of mips_sloper (detailed cosmic ray information) along with the perl scripts written by Chad Engelbracht. The differences between the ground-based and in-orbit cosmic ray behaviors will be enumerated.

Software Requirements

Actions Following Analysis

No action is required if the in-orbit and ground-based electronic nonlinearities are equivalent. The ground-based correction files will then be used (as planned) in the reduction of all MIPS data.

If the in-orbit and ground-based electronic nonlinearities are not equivalent, then the datasets generated for this task will be used as the basis of new electronic nonlinearity calibration files. Additional datasets with more finely spaced stim amplitudes may be required to recover the same DN range of the ground-based correction.

The in-orbit noise and cosmic ray properties are expect to be different at some level than those meaured with ground-based data. As such, adjustments to the Ge noise model and cosmic ray rejection parameters will be required.

Failure Modes and Responses

If this task fails, the reason of the failure needs to be determined and corrected. This task would then need to be rerun.

Additional Notes