CALBLOCK-PV-016: NISP Persistence¶
Observation configuration file¶
Scheduling¶
The persistence calibration consists of three parts. The main calibration, and two shorter checks. The execution sequence is as follows:
Immediately after CALBLOCK-PV-010: NISP LED flats, execute persistence check 1. If the latter fails, then CALBLOCK-PV-010: NISP LED flats must be repeated as well.
1-2 weeks later, execute the nominal persistence calibration, without significant NISP flat activities in between (if possible). In case of failure, repeat as soon as possible without significant NISP flat activity prior to the repetition.
1-2 weeks later, repeat the shorter persistence check 2. In case of failure, repeat at next possible opportunity.
Time-critical¶
Persistence check 1 must be taken immediately after CALBLOCK-PV-010: NISP LED flats.
Nominal persistence calibration is taken 1-2 weeks after check 1.
Persistence check 2 is taken 1-2 weeks after the nominal calibration.
Ideally, no NISP osbervations are scheduled afterwards that could be affected by still decaying persistence, in particular CALBLOCK-PV-001: Self Calibration, CALBLOCK-PV-018: NISP Nonlinearity, CALBLOCK-PV-012: NISP Dark Current and Snowballs, CALBLOCK-PV-017: NISP Reciprocity Failure, and CALBLOCK-PV-002: NISP-P and VIS Absolute Photometric Standards.
Dependencies¶
CALBLOCK-PV-010: NISP LED flats must be done at least one week before the nominal persistence check, as it could affect the persistence behaviour.
Objective¶
Persistence has been characterized extensively on ground, when the detectors were turned on while still being warm. A less comprehensive calibration campaign with detectors turned on when cold followed. The idea is that the timescales of the traps do not change when turned on cold, just their overall amount per pixel. Using the second calibration campaign one can then update the relevant parameters in the models.
In flight, detectors are turned on cold, when persistence is significantly lower.
The objective of these observations is to determine the timescales and amplitudes. Additional checks are run to see if the persistence is stable over time, and whether it is affected by immediately preceding NISP LED flats. The expectation is that no long-term memory affects are detected, and that the persistence is stable.
Persistence in Euclid H2RGs has been shown to be achromatic (A. Wacynski, NISP DWG5 2015), hence we test only with a single LED.
Observations¶
Parallel schedule suggestion: CALBLOCK-PV-024: VIS On-sky Nonlinearity, CALBLOCK-PV-008: Phase Diversity Calibration
To determine the amplitudes and time constants of the persistence signal, the persistence has to be measured at fluences of 10, 20, 30, 40, 50 kADU (above the baseline level). The long time constants will be measured only after the highest fluence, which gives the best S/N. LED ‘E’ is used for all persistence tests. Measurements at fluences below 50 kADU are repeated three times to improve S/N.
# Fluence [kADU] |
Flux [e-/s] |
Flux [ADU/frame] |
Int [mA] |
PWM [%] |
10 |
230 |
167.3 |
10.0 |
19.8 |
20 |
460 |
334.6 |
10.0 |
37.4 |
30 |
690 |
501.9 |
30.0 |
14.6 |
40 |
920 |
669.2 |
30.0 |
18.4 |
50 |
1150 |
836.5 |
30.0 |
22.3 |
LED = 'E'
fluence = 30 kADU (690 e-/s)
repeat 3x:
Take 1 flat field with said fluence in photo-MACC mode.
Take 5 photo-MACC darks and 10 spectro-MACC darks
LED = 'E'
for fluence in [10,20,30,40,50 kADU] (230, 460, 690, 920, 1150 e-/s):
if (fluence < 50 kADU):
repeat 3x:
Take 1 flat field with said fluence in photo-MACC mode.
Take 5 photo-MACC darks and 10 spectro-MACC darks
if (fluence == 50 kADU):
Take 1 flat field with said fluence in photo-MACC mode.
Take 30 spectro-MACC darks
LED = 'E'
for fluence in [10,30,50 kADU] (230, 690, 1150 e-/s):
if (fluence < 50 kADU):
repeat 3x:
Take 1 flat field with said fluence in photo-MACC mode.
Take 5 photo-MACC darks and 10 spectro-MACC darks
if (fluence == 50 kADU):
Take 1 flat field with said fluence in photo-MACC mode.
Take 30 spectro-MACC darks
After 4.5 hours, the persistence flux should have dropped below 0.023 e-/s/pixel (R-CAL-B-NP-1476), but ground characterization data indicate that this might be longer.
Fulfilling¶
Targets and pointing constraints¶
Pointing: Straylight suppression as per MOCDA-SYS-003.
Instrument configuration¶
Instrument: NI-CU on, NI-CU off
Methodology / Uplink procedure¶
Entity: NISP
Commanding Method: NISP: Observation
Dither Sequence: None
Inter-operability constraints¶
None
In-orbit duration¶
In-orbit Duration: 42.8 h
Nominal persistence calibration: (111s+5*111s+10*565s)*3 * 4 LED + (111s+30*565s) = 25.8 h
Persistence check 1: (111s+5*111s+10*565s)*3 = 1.7 h
Persistence check 2: (111s+5*111s+10*565s)*3 * 2 fluences + (111s+30*565s) = 15.3 h
Data volume¶
Total: 51562 MB
Nominal persistence calibration: 13*NP + 60*NP + 150*NS = 28757 MB (flats, photo-MACC darks, spectro-MACC darks)
Persistence check 1: 3*NP + 15*NP + 30*NS = 5952 MB
Persistence check 2: 7*NP + 30*NP + 90*NS = 16853 MB
Processing input¶
Ground Processing Input Data: Darks (without persistence)
Data Description: 27 flat fields, 150 photo-MACC darks, 300 spectro-MACC darks (overall for the nominal and the check sequences)
Required accuracy, constraints¶
Must be able to evaluate the persistence signal per pixel.
Validation¶
Compare the observed persistence (flats, bright stars) with the predictions by the persistence model. Update the time constants and amplitudes if statististically significantly different from ground test data.
Recovery¶
Must be repeated at the next convenient opportunity.
Quality control parameters¶
DataModel: https://gitlab.euclid-sgs.uk/
Contact person¶
NISP-P calibration scientist