CALPRODUCT-VS-005: VIS CTI Charge Injection Lines¶
Parent requirement¶
Scheduling¶
Execute the full sequence six times at the beginning of the PV phase.
Execute once every 1.5 ~ 2 weeks, during the PV phase.
Daily, as part of the ROS.
Time-critical¶
No
Dependencies¶
None
Objective¶
Radiation damage will increase the degree of Charge Transfer Inefficiency (CTI) in the VIS CCDs. The CTI is corrected
for in the VIS science images using a calibrated CTI model. This CalProduct provides the CTI model, based on
charge injection line (CIL) data and flat fields taken during PV phase, and continuously as part of the ROS.
Observations¶
PV phase CIL parameters
The PV phase CTI calibrations (sequence of 42 CIL patterns) are in addition to the ROS (sequence of 32) seen here, and are defined in CALBLOCK-PV-028: VIS CTI Charge Injection.
ROS charge injection line (CIL) parameters
8 charge injection line (CIL) images are taken daily during the nominal survey, along with flat-field images, to calibrate the continuously increasing level of CTI.
Constant CIL parameters (ROS):
VSTART_CHG_INJ = 16
VEND_CHG_INJ = 2066
VSTART = 0
VEND = 2086
#Number |
Day |
Pattern |
CHG_INJ_ON |
CHG_INJ_OFF |
ID_Delay [ms] |
IG1 [V] |
IG2 [V] |
IG2-IG1 [V] |
30us_DWELL(CHINJ_RoDly) |
1 |
1 |
CIR3 |
420 |
100 |
2.5 |
4.25 |
6 |
1.75 |
on |
2 |
1 |
CIR1 |
214 |
200 |
2.5 |
4.75 |
6 |
1.25 |
on |
3 |
1 |
CIR1 |
214 |
200 |
2.5 |
6.25 |
6 |
-0.25 |
on |
4 |
1 |
CIR1 |
214 |
200 |
1.5 |
4.25 |
6 |
1.75 |
on |
5 |
1 |
CIR1 |
214 |
200 |
1.5 |
4.75 |
6 |
1.25 |
on |
6 |
1 |
CIR1 |
214 |
200 |
1.5 |
7 |
6 |
-1 |
on |
7 |
1 |
CIR1 |
214 |
200 |
1.5 |
10 |
4 |
-6 |
on |
8 |
1 |
CIR1 |
214 |
200 |
1.5 |
5.35 |
6 |
0.65 |
on |
9 |
2 |
CIR1 |
214 |
200 |
1.5 |
4.75 |
6 |
1.25 |
OFF |
10 |
2 |
CIR2 |
260 |
1500 |
2.5 |
4.75 |
6 |
1.25 |
on |
11 |
2 |
CIR2 |
260 |
1500 |
2.5 |
6.25 |
6 |
-0.25 |
on |
12 |
2 |
CIR2 |
260 |
1500 |
1.5 |
4.25 |
6 |
1.75 |
on |
13 |
2 |
CIR2 |
260 |
1500 |
1.5 |
4.75 |
6 |
1.25 |
on |
14 |
2 |
CIR2 |
260 |
1500 |
1.5 |
7 |
6 |
-1 |
on |
15 |
2 |
CIR2 |
260 |
1500 |
1.5 |
10 |
4 |
-6 |
on |
16 |
2 |
CIR2 |
260 |
1500 |
1.5 |
5.35 |
6 |
0.65 |
on |
17 |
3 |
CIR3 |
420 |
100 |
2.5 |
4.25 |
6 |
1.75 |
on |
18 |
3 |
CIR3 |
420 |
100 |
2.5 |
4.75 |
6 |
1.25 |
on |
19 |
3 |
CIR3 |
420 |
100 |
2.5 |
6.25 |
6 |
-0.25 |
on |
20 |
3 |
CIR3 |
420 |
100 |
1.5 |
4.25 |
6 |
1.75 |
on |
21 |
3 |
CIR3 |
420 |
100 |
1.5 |
4.75 |
6 |
1.25 |
on |
22 |
3 |
CIR3 |
420 |
100 |
1.5 |
7 |
6 |
-1 |
on |
23 |
3 |
CIR3 |
420 |
100 |
1.5 |
10 |
4 |
-6 |
on |
24 |
3 |
CIR3 |
420 |
100 |
1.5 |
5.35 |
6 |
0.65 |
on |
25 |
4 |
CIR3 |
420 |
100 |
2.5 |
4.25 |
6 |
1.75 |
on |
26 |
4 |
CIR2 |
260 |
1500 |
1.5 |
4.25 |
6 |
1.75 |
OFF |
27 |
4 |
CIR4 |
53 |
50 |
2.5 |
6.25 |
6 |
-0.25 |
on |
28 |
4 |
CIR4 |
53 |
50 |
1.5 |
4.25 |
6 |
1.75 |
on |
29 |
4 |
CIR4 |
53 |
50 |
1.5 |
4.75 |
6 |
1.25 |
on |
30 |
4 |
CIR4 |
53 |
50 |
1.5 |
5.35 |
6 |
0.65 |
on |
31 |
4 |
CIR4 |
53 |
50 |
1.5 |
7 |
6 |
-1 |
on |
32 |
4 |
CIR4 |
53 |
50 |
1.5 |
10 |
4 |
-6 |
on |
Fulfilled by¶
CALBLOCK-PV-028: VIS CTI Charge Injection
Targets and pointing constraints¶
None
Instrument configuration¶
Instrument: Wide survey
Methodology / Uplink procedure¶
Entity: VIS
Commanding Method: VIS
Dither Sequence: ROS
Inter-operability constraints¶
None
Data volume¶
192*VB = 48000 MB (PV phase)
8*VB = 2000 MB (per day, during nominal survey)
Processing input¶
Ground Processing Input Data:
Data Description:
Processing method¶
The charge injection and flat field images are bias and NL corrected. A CTI model is then fitted using the VIS_CTI PE, which is performed a nonlinear search using the nested sampling algorithm MultiNest.
Processing output¶
Updated parameters on the CTI model for that given observation data (.json of best fit parameters is stored via the DataModel).
Additional information and metadata on the model-fit (e.g. nested sampling samples, summary statistics).
Required accuracy, constraints¶
The CTI model used to correct CTI in the VIS detectors must correct CTI to better than \(4.0\times10^{-3}\) (TBC).
Processing tools¶
VIS_CTI PE
Validation¶
Reduced chi-squared of CTI calibration pipeline model-fit is close to 1.
Use CTI correction algorithm on charge injection data and check that residual EPER trails produce spurious ellipticity below 1.0e-4 using equation (14) of Israel et al 2015 (https://arxiv.org/abs/1506.07831).
Recovery¶
Update the CTI calibration model.
Quality control parameters¶
DataModel: https://gitlab.euclid-sgs.uk/
Contact person¶
VIS instrument scientist