Introduction¶
VMPZ-ID products, used in other LE3 Processing Functions, consist in (with increasing complexity):
Reconstructing accurate survey footprint (using MER tiling in HEALPix MOC)
Collecting bit Masks derived at previous levels (VIS, NIR, EXT) and construction the coverage mask (footprint+not masked regions in bit masks)
Collecting instrumental/environmental information needed to compute the limiting magnitude and visibility masks
estimating the depth maps based on rms Noise
estimating the photometric visibility mask and the random catalog for a given selection used for 2PCF-WL, PK-WL, 2PCF-GC, 3PCF-GC, PK-GC, DET-CL, PROF-CL and VMSP-ID. They are also expected to be used by SWG-GC, SWG-WL and SWG-CL..
VMPZ-ID is triggered at the MER tile level, where all products are first produced as (potentially weighted) MOC Healpix maps, at a given MOC order. In the following, this stage is named the stage 1.
A second step, prior to triggering other “client” LE3 processing functions implies “merging” the MOC maps, and a HEALPix partial map or MOC map is produced at the resolution prescribed by the user in the parameter files. Potential mangle maps could be derived from this product. In the following, this stage is named the stage 2.
VMPZ-ID masks and random catalogs will be available by tiles and for the full survey.
Survey footprint¶
For the survey footprint, beside parameters VMPZIDParamsFootprint the footprint requires:
for stage 1 (processing on MER tiles), products containing the list of coordinates describing the geometry of the survey for the set of given band/instrument are first ingested (e.g.: the ReconsFPAPointing in VIS VISObsFrame for NIR/VIS, the ImgSpatialFootprint in EXT CalibratedFrame if precise enough). The fraction of HEALPix pixel covered is reported in a VMPZIDMOCFootprintMask.
for stage 2 (processing at skypatch level), a set of MOC HEALPix Maps VMPZIDMOCFootprintMask are processed on the different MER tiles overlapping with the prescribed region.
The two stages will produce a VMPZIDHEALPixFootprintMask or VMPZIDMOCFootprintMask.
Bit Masks and coverage mask¶
The coverage masks correspond to regions of the survey footprint that have not been flagged using the bitmask. It is therefore the same format as the survey footprint, but the flagged areas are set to 1. Parameters are set in VMPZIDParamsCoverage.
The two stages will produce the product VMPZIDHEALPixCoverageMask or VMPZIDMOCCoverageMask. In case of sky patch processing, or a mangle file VMPZIDMangleCoverageMask can also be outputted, using VMPZIDParamsMangle parameter files.
For the bit masks, besides parameters VMPZIDParamsBitMask, and a HEALPix VMPZIDMOCFootprintMask, one would need:
for stage 1, the pixel flag maps defined in MER MERMosaic or (see in human readable format) for the different bands/instruments, to produce VMPZIDMOCBitMask
for stage 2, a set of VMPZIDMOCBitMask computed on the different MER tiles overlapping with the prescribed region to produce VMPZIDHEALPixBitMask or VMPZIDMOCBitMask
In case of sky patch processing, a mangle file VMPZIDMangleCoverageMask can also be outputed, using VMPZIDParamsMangle parameter files.
Instrumental/Environmental Information¶
Using parameters VMPZIDParamsInfoMaps, MOC maps of instrumental and environmental effects are first collected in a product VMPZIDMOCCollectInfoMaps. This implies to have access to all relevant statistics (mean/median/max/min?) on relevant quantities to compute the limiting magnitude, such as PSF/seeing FWHM, background level, RMS map, exposureTime, airmass,solar aspect angle, zodiacal light emissions.
In the table below are listed a series of potential inputs to collect this maps.
Depth Maps¶
The depth map is then estimated using parameters VMPZIDParamsDepth, and information collected in VMPZIDMOCCollectInfoMaps. In stage 1 MOC HEALPix maps VMPZIDMOCDepth are produced at the MER level, while in stage 2 the data is gathered at the sky patch level in either partial HEALPix maps VMPZIDHEALPixDepth or VMPZIDMOCDepth.
Photometric Visibility Mask and Random Catalog¶
Along with parameters VMPZIDParamsVisibility and the ref:VMPZIDMOCDepth <VMPZIDMOCDepth> maps, the photometric visibility mask can be produced and stored as partial HEALPix map VMPZIDHEALPixVisibility or MOC VMPZIDMOCVisibility. A random catalog VMPZIDRandomCatalog can then be produced using luminosity function representative of the bin/population selected, or a proxy where to draw samples (deep survey).
Input products
Output products