CALPRODUCT-VS-013: VIS Large-Scale Flat¶
Parent requirement¶
Scheduling¶
Monthly
Time-critical¶
No
Objective¶
The illumination of the VIS FPA is not expected to be perfectly uniform, due to various factors such as:
Baffle vignetting at the outermost corners of the FPA (LED flats)
An imperfect edge of the M3 mirror
Coating variations on folding mirrors FoM1 and FoM2, far outside the pupil plane, could lead to throughput variations at arcminute scales.
Molecular contamination could cause spatial variation of mirror reflectivities.
The VIS shutter causes uneven illumination (characterized independently through CALPRODUCT-VS-028: VIS Shuttermaps.
Apodization
The objective is to reconstruct matching broad-band large-scale flats for VIS from the CALBLOCK-F-001: Self Calibration observations, using stellar photometry. The large-scale flat removes simultaneously any residual large-scale non-uniformity present in the VS-CU flats (CALPRODUCT-VS-014: VIS LED Pixel Response Non-uniformity (PRNU)), as well as any large-scale illumination effects from the PLM.
Fulfilled by¶
Data volume¶
The same data used for CALPRODUCT-VS-012: VIS Dichroic Ghost Model
Processing input¶
Ground Processing Input Data: BPM
Data Description:
Processing output¶
Large-scale flat for VIS. Also produce a coarsely binned (e.g. 100x100, or 256x256) image for trend analysis.
Required accuracy, constraints¶
The VIS large-scale flat reconstructed from a single visit to the Self-cal field must be accurate to better than 0.3%.
Processing tools¶
OU-VIS Large Scale Flat processing element
Quality control parameters¶
DataModel: https://gitlab.euclid-sgs.uk/
Contact person¶
VIS instrument scientist