CALPRODUCT-NI-014: NISP Slew Darks¶
Parent requirement¶
Scheduling¶
During field slews.
Time-critical¶
No.
Objective¶
During a field slew, a single photo-MACC dark frame is obtained (i.e. once per ROS). The slew darks will be contaminated by persistence from the zodiacal background, as well as from astrophysical sources from previous exposures. Persistence by the latter can be removed using median combination. Slew darks will therefore essentially have a thermal component (the classical dark current) and a persistence component from the zodiacal background.
Slew darks are useful for continuous detector monitoring. Any baseline drifts should also be readily visible in the darks, as a characteristic pattern specific to each detector.
Fulfilled by¶
Instrument configuration¶
Instrument: NI-FWA closed, NI-GWA in any RGS or BGS position
Inter-operability constraints¶
VS-CU off
Processing input¶
Ground Processing Input Data: BPM, persistence masks
Data Description: single photo-MACC dark
Processing method¶
Compute the mean (or mode) per detector. It should be as expected given the zodiacal background in the previous exposure. The number of hot pixels must be trended.
Processing output¶
BPM update (if we observe steady changes in the number of hot pixels)
Histograms of slew dark+persistence current for each detector
Comparison between spatial and temporal rms
Trend analysis on a monthly basis: number of hot pixels, change in spatial dark current pattern and histogram, IPC matrix from isolated, single hot pixels
Required accuracy, constraints¶
There is no accuracy requirement.
Spatial variations within TBD % (absence of baseline drifts in single darks)
Spatial appearance as expected from ground-based measurements (absence of baseline drifts in single darks)
Absence of light leaks
Number of hot / bad pixels within expectations
Mean or statistical mode per detector should be correlating with background signal in previous exposure.
Processing tools¶
L1 dark pipeline, trending statistics, histogram
Validation¶
Check that the mean dark / persistence signal in the exposures is within expectations given the zodiacal background in the previous exposure.
Recovery¶
Not necessary.
Quality control parameters¶
DataModel: https://gitlab.euclid-sgs.uk/
Contact person¶
NISP-P calibration scientist