Output Product: HEALPix Bit Mask¶
Data Product Name¶
DpdHealpixBitMaskVMPZ
Data Product Custodian¶
IDVMPZ
Name of the Schema File¶
euc-le3-id-vmpz-HealpixBitMask.xsdLast Edited for DPDD Version¶
1.1
Processing Elements Creating / Updating / Using the Product¶
Creators:
VMPZ_Main (LE3_VMPZ_ID_Main)
Consumers:
VMPZ_Visibility (LE3_VMPZ_ID_Visibility)
Processing function using the data product¶
2PCF-WL, PK-WL, 2PCF-GC, 3PCF-GC, PK-GC, DET-CL, PROF-CL, VMSP-ID
SWG-GC, SWG-WL, SWG-CL
Proposed for inclusion in EAS/SAS¶
This product is proposed for inclusion in SAS: yes
This product is used by different PFs in OU-LE3 and expected to be used in scientific analysis in SWG-GC, SWG-WL and SWG-CL.
Data Product Elements¶
- Header:
object of type sys:genericHeader
- Data:
object of type vmpzid:bitMaskHealpixVMPZ
- QualityFlags:
object of type dqc:sqfPlaceHolder
- Parameters:
object of type ppr:genericKeyValueParameters
Detailed Description of the Data Product¶
This output product contains essentially a container for a map for one or more flags in the bitmask as defined in the MER definition.
It includes in BitMaskHealpix a container with a FITS file (of type le3.id.vmpz.healpixbitmask) describing the flag(s) selected, in partial HEALPix format (one bit per column), for a given observed band/instrument (Euclid/EXT), and a raw description with polygons of the envelope of the sky covered is added as well to ease future queries on the product (SpatialCoverage metadata, see spatialFootprint). The bit selected is also indicated in the product. Finally, the mask parameters BitMaskHealpixParams can optionally be associated to the product.
Keywords (Primary HDU)¶
The primary HDU is expected to contain the following keywords, characterizing important parameters of the input product:
SIMPLE |
/ |
||
BITPIX |
/ |
||
NAXIS |
/ |
||
EXTEND |
/ |
||
DATE-OBS |
/ |
e.g. Start date for observations considered |
|
DATE-END |
/ |
e.g. End date for observations considered |
|
TELESCOP |
/ |
e.g. Euclid or -1 |
|
INSTRUME |
/ |
e.g. VIS or -1 |
|
FILTER |
/ |
e.g. VIS or -1 |
|
FILTLST |
/ |
index for combination of filters if intersection of footprints |
|
TILEID |
/ |
e.g. 5237, or -1 if not single tile |
|
LISTID |
/ |
Product ID for a MER list of tiles |
|
NSIDE_WK |
/ |
Nside used for mosaic frame to HEALPix |
|
BITSEL |
/ |
e.g. Bit mask selection applied based on MER binary values |
|
SOFTNAME |
/ |
||
SOFTVERS |
/ |
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END |
|||
DATE-OBS: start of observation with format ‘yyyy-mm-ddThh:mm:ss.sss’ [StringKeyword]
DATE-END: end of observation with format ‘yyyy-mm-ddThh:mm:ss.sss’ [StringKeyword]
TELESCOP: name of the telescope [StringKeyword]
INSTRUME: name of the instrument [StringKeyword]
FILTER: name of the filter [StringKeyword]
FILTLST: selection of filter if intersection of multiple footprints [StringKeyword]
TILEID: identifier of the MER Tile processed (-1 if multiple Tiles) [IntegerKeyword]
LISTID: identifier of a MER list of tiles product (-1 if single Tile) [StringKeyword]
NSIDE_WK: Nside parameter used for frame->HEALPix [StringKeyword]
BITSEL: identifier of the bit of combination of bits reported in the bitmask (e.g. 0 for least significant bit,..,18) [StringKeyword]
and basic software parameters:
SOFTNAME: name of software used [StringKeyword]
SOFTVERS: version of software used [StringKeyword]
Partial HEALPix Footprint Table (First Extension, Binary Table)¶
The following keywords are used to describe what HEALPix conventions are followed:
HDU BIT_MASK |
|||
|---|---|---|---|
Keywords |
XTENSION |
string |
|
BITPIX |
integer |
||
NAXIS |
integer |
||
NAXIS1 |
integer |
||
NAXIS2 |
integer |
||
PCOUNT |
integer |
||
GCOUNT |
integer |
||
TFIELDS |
integer |
||
TTYPE1 |
string |
||
TFORM1 |
string |
||
TTYPE2 |
string |
||
TFORM2 |
string |
||
PIXTYPE |
string |
||
ORDERING |
string |
||
COORDSYS |
string |
||
EXTNAME |
string |
||
NSIDE |
integer |
||
INDXSCHM |
string |
||
OBJECT |
string |
||
2 columns table |
|||
Columns |
PIXEL |
Index of the HEALPix pixel cell |
FITS K |
WEIGHT |
Mask value, ranging from O to 1 |
FITS E |
|
TTYPE1 (= ‘PIXEL’) [StringKeyword]
TFORM1 (= ‘K’) [StringKeyword]
TTYPE2 (= ‘WEIGHT’) [StringKeyword]
TFORM2 (= ‘E’) [StringKeyword]
PIXTYPE (= ‘HEALPIX’) [StringKeyword]
ORDERING (= ‘RING’ or ‘NESTED’) [StringKeyword]
COORDSYS (= ‘C’=celestial, ‘E’=ecliptic or ‘G’=galactic) [StringKeyword]
EXTNAME (= ‘BIT_MASK’) [StringKeyword]
NSIDE [IntegerKeyword]
INDEXSCHM (= ‘EXPLICIT’) [StringKeyword]
OBJECT (= ‘PARTIAL’) [StringKeyword]
The table is then expected to contain the following columns:
PIXEL: index of pixel [K, int64]
WEIGHT: weight associated to pixel in [0,1] indicating the fraction of the pixel actually flagged by the bitN of the mask (1: fully flagged regions) [E, float32]
Warning
We have here a solution where we collect just one bit/a combination of bits in the bitmask for a single band of an instrument in a partial HEALPix file. Note that the conversion frame->HEALPix implies that we lose the binary format if we want the fraction of sky flagged or not in a HEALPix pixel - and therefore we need the single bit products. The alternative is to have a vectorial form, e.g TFORM2=’19E’