24 um IOC Darks

Principal: James Muzerolle
Deputy: Karl Gordon
Data Monkey(s): Kate Su, Casey Papovich
Priority: Critical
Downlink Priority: Normal
Analysis Time: 24 hours
Last Updated:

Objective

Dark current and read noise measurements.

Description

Point to the 24 µm dark position. Take 10-second dark measurements using the Dark IER, and 10-second read noise measurements using the Read Noise IER. ***Note: the read noise observations will NOT be obtained until Campaign O!!***

Data Collected

50 10-second SUR DCEs from the Dark IER (all campaigns) 35 10-second SUR DCEs from the Read Noise IER (Campaign O and later only).

Data Reformatting Requirements

Array Data Desired:

24 µm

Data Reformatting Option:

Special Instructions:
All DCEs for each IER should be packed into one fits file with extensions. Two files should be generated: one with 50 DCEs (darks), and one with 35 DCEs (read noise).

Task Dependencies

Calibration Dependencies

Output and Deliverable Products

Data produced by the dark IER will be used to construct a dark calibration image for use with the DAT/pipeline. Data from the read noise IER will be used to determine the read noise, checking for stability by comparing with previous ground data and earlier IOC campaigns. Before Campaign O, the read noise IER will not be observed, but read noise measurements can be made with the data from the dark IER - however, this will not be directly comparable to the ground test read noise measurements!! The data will also be used to examine any scattered light that may be present.

Data Analysis

The data will be processed with the DAT: mips_sloper without dark subtraction (-b), mips_caler without flat fielding (-F; here, this step is necessary only for proper input into mips_enhancer), and mips_enhancer (with -f to specify the input *.cal.fits file with extensions) to combine multiple DCEs generated by the dark IER into a dark current calibration image. The IDL script 'get_rdnoise.pro", which is included in the DAT distribution, will be used to determine the read noise from the data generated by the read noise IER. This should be run with n_dce_rej=1 in order to remove the bias boost DCE from the analysis, since the counts there are always significantly reduced from those of the non-boost DCEs. Compare the dark calibration image with ground-test and previous IOC dark images (when available), check for different counts, the appearance of pattern noise (e.g., striping in the image, such as produced by excessive EM interference). IOC darks will likely contain higher counts than ground darks due to scattered light. This should be quantified by dividing by the truly dark ground-test darks to obtain images of the scattered component, and tracked for variability by comparing with previous IOC darks. Compare the read noise measurement with previous ground tests (see the 24um read noise log) and IOC measurements, check for excess noise.

Software Requirements

Actions Following Analysis

Dark calibration images should be put in the appropriate place for distribution, unless the data are significantly discrepant (i.e., excess noise, large scattered light component). If counts are unexpectedly high, check that CSMM was at the expected dark position. Check CE and detector temperature. Check for pattern noise or larger than expected read noise. Ensure that there is no latent signal from prior exposure to a bright source.

Failure Modes and Responses

If darks are unusable, possible reasons (from the above checklist) should be logged.

Additional Notes