Background-Subtracted Mosaic Product

Data Product Name

DpdMerBksMosaic

Data Product Custodian

MER

Name of the Schema File

euc-mer-BksMosaic.xsd

Last Edited for DPDD Version

2.0

Processing Elements Creating / Updating / Using the Product

Creators:

• MER_Background

• MER_CatalogPsfCalculation

• MER_Compression

Consumers:

• MER_Detection

• MER_CatalogPsfCalculation

• MER_PsfExtraction

• MER_LowResPsfExtraction

• MER_Kernel

• MER_Morphology

• MER_Photometry

• MER_CatalogAssembly

• MER_Compression

• MER_MorphoFitting

• MER_Validation

Processing Function Using the Product

MER, SIR, SHE

Proposed for Inclusion in EAS/SAS

This product is proposed for inclusion in the SAS: yes.

These products combine all the imaging data that overlap the MER tiles, so they will be very useful for any scientific studies that require image data.

Data Product Elements

Header:

object of type sys:genericHeader

Data:

object of type mer:merBksMosaic

QualityFlags:

object of type dqc:sqfDpdMerBksMosaic

Parameters:

object of type ppr:genericKeyValueParameters

Detailed Description of the Data Product

This product is the result of applying the MER mosaicing and MER background subtraction Processing Elements to the VIS calibrated quad frames, the NIR calibrated frames, and the EXT stacked frames.

MER mosaics are built using the MER tile outer spatial footprint as a reference, and share the same field of view and pixel scale (0.1’’ x 0.1’’) for all bands. Their size is typically 32’ x 32’ for WIDE tiles, and 17’ x 17’ for DEEP tiles.

Before coaddition, the background models calculated in the VIS and NIR pipelines are subtracted to the input images. The EXT stacked frames habe been already background-subtracted and the MER pipeline just rebins them to the target 0.1’’ x 0.1’’ pixel size. These background models are not propagated by the MER pipeline and cannot be added again to the MER mosaics.

A second background subtraction step is applied in the MER pipeline to remove any remaining background in the mosaiced images. The background model calculated in this step is stored in the background FITS file.

MER receives the Point Spread Functions (PSFs) measured by the VIS, NIR and EXT pipelines and propagates them to the MER mosaic grid to calculate a different PSF stamp for each individual source and band. The propagated PSF stamps are stored in the mosaic PSF FITS file.

The imaging and rms data have, depending on the provenience, different units with:

• VIS in [ADU/sec]

• NIR in [electrons]

• EXT in arbitrary units

In all cases, image units can be translated to physical units using the mosaic Zero Point and the well known formula:

(9)\[m_\text{AB} = -2.5 \times \log_{10}\left(\text{image_value}\right) + \text{ZeroPoint}\]

The main elements inside the MER background-subtracted mosaic product are:

• Instrument: The instrument name (VIS, NIR, DECAM) and the telescope name (Euclid, NOAO, LSST).

• Filter: The filter name (e.g., VIS, NIR_Y, NIR_J, NIR_H, DECAM_g, LSST_u).

• WCS: The mosaic astrometric parameters (e.g., CTYPE1, CRVAL2, CRPIX1, CD1_1)

• ZeroPoint: The photometric reference zero point to convert the image untis to AB-magnitudes.

• ImgSpatialFootprint: The mosaic spatial footprint.

• TileIndex: The MER tile index.

• PatchIdList: The sky patch ids associated to the product.

• ObservationIdList: List of unique IDs identifying the Euclid observations that were used to generate the product.

• CalblockIdList: The calibration block ids associated to the product.

• CalblockVariantList: The calibration block variants associated to the product.

• ProcessingMode: The MER pipeline processing mode (e.g. WIDE, DEEP) used to generate the product.

• ReferenceObservationDateTime: Reference observation date time for GAIA proper motion correction (only applicable to Euclid observations).

• FirstObservationDateTime: Observation date time of the first Euclid observation used to generate the product.

• LastObservationDateTime: Observation date time of the last Euclid observation used to generate the product.

• DataStorage: Element that links to a FITS file containing the mosaic signal data set.

• RmsStorage: Element that links to a FITS file containing the mosaic rms data set.

• FlagStorage: Element that links to a FITS file containing the mosaic flag data set.

• PsfModelStorage: Element that links to a FITS file containing the mosaic catalog PSF.

• FilterTransmissionStorage: Element that links to a FITS file containing the mosaic average filter transmission wavelength data set.

• LayersStorage: Element that links to a FITS file containing the mosaic input layers information (only provided for the Euclid bands).

• BrightStarMasksStorage: Element that links to a json file containing the mosaic bright star spatial masks.

• BackgroundStorage: Element that links to a FITS file containing the subtracted background model.

• QualityParams: The mosaic image quality parameters.

• BackgroundQualityParams: The mosaic background quality parameters.

Image FITS file

This FITS file contains the background-subtracted mosaic image.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	AUTHOR	Who ran the software (Swarp keyword)	string
	BITPIX	array data type	integer
	CD1_1	Linear projection matrix	double
	CD1_2	Linear projection matrix	double
	CD2_1	Linear projection matrix	double
	CD2_2	Linear projection matrix	double
	CENTERT1	CENTER_TYPE config parameter (Swarp keyword)	string
	CENTERT2	CENTER_TYPE config parameter (Swarp keyword)	string
	COMBINET	COMBINE_TYPE config parameter for SWarp (Swarp keyword)	string
	CRPIX1	Reference pixel on this axis	double
	CRPIX2	Reference pixel on this axis	double
	CRVAL1	World coordinate on this axis	double
	CRVAL2	World coordinate on this axis	double
	CTYPE1	WCS projection type for this axis	string
	CTYPE2	WCS projection type for this axis	string
	CUNIT1	Axis unit	string
	CUNIT2	Axis unit	string
	DATASETR	The pipeline data set release	string
	DATE	When it was started (GMT) (Swarp keyword)	string
	EQUINOX	Mean equinox	double
	FILTER	The filter name	string
	MAGZERO	AB zeropoint	double
	NAXIS	number of array dimensions	integer
	NAXIS1	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	NAXIS2	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	ORIGIN	Where it was done (Swarp keyword)	string
	PIPDEFID	The pipeline definition id	string
	PPLANID	The parent plan id	string
	PPOID	The pipeline processing order id	string
	PSCALET1	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSCALET2	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSWNAME	The pipeline software name	string
	PSWREL	The pipeline software release	string
	RADESYS	Astrometric system	string
	RESAMPT1	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	RESAMPT2	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	SIMPLE	conforms to FITS standard	logical
	SOFTAUTH	Maintainer of the software (Swarp keyword)	string
	SOFTDATE	Release date of the software (Swarp keyword)	string
	SOFTINST	Institute (Swarp keyword)	string
	SOFTNAME	The software that processed those data (Swarp keyword)	string
	SOFTVERS	Version of the software (Swarp keyword)	string

RMS FITS file

This FITS file contains the propagated rms associated to the mosaic. Note that the VIS and NIR rms values contain a Poisson noise contribution that could be significant for bright sources, while the EXT rms values currently do not include this contribution.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	AUTHOR	Who ran the software (Swarp keyword)	string
	BITPIX	array data type	integer
	CD1_1	Linear projection matrix	double
	CD1_2	Linear projection matrix	double
	CD2_1	Linear projection matrix	double
	CD2_2	Linear projection matrix	double
	CENTERT1	CENTER_TYPE config parameter (Swarp keyword)	string
	CENTERT2	CENTER_TYPE config parameter (Swarp keyword)	string
	COMBINET	COMBINE_TYPE config parameter for SWarp (Swarp keyword)	string
	CRPIX1	Reference pixel on this axis	double
	CRPIX2	Reference pixel on this axis	double
	CRVAL1	World coordinate on this axis	double
	CRVAL2	World coordinate on this axis	double
	CTYPE1	WCS projection type for this axis	string
	CTYPE2	WCS projection type for this axis	string
	CUNIT1	Axis unit	string
	CUNIT2	Axis unit	string
	DATASETR	The pipeline data set release	string
	DATE	When it was started (GMT) (Swarp keyword)	string
	EQUINOX	Mean equinox	double
	FILTER	The filter name	string
	MAGZERO	AB zeropoint	double
	NAXIS	number of array dimensions	integer
	NAXIS1	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	NAXIS2	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	ORIGIN	Where it was done (Swarp keyword)	string
	PIPDEFID	The pipeline definition id	string
	PPLANID	The parent plan id	string
	PPOID	The pipeline processing order id	string
	PSCALET1	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSCALET2	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSWNAME	The pipeline software name	string
	PSWREL	The pipeline software release	string
	RADESYS	Astrometric system	string
	RESAMPT1	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	RESAMPT2	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	SIMPLE	conforms to FITS standard	logical
	SOFTAUTH	Maintainer of the software (Swarp keyword)	string
	SOFTDATE	Release date of the software (Swarp keyword)	string
	SOFTINST	Institute (Swarp keyword)	string
	SOFTNAME	The software that processed those data (Swarp keyword)	string
	SOFTVERS	Version of the software (Swarp keyword)	string

Flag FITS file

MER propagates the image bit flags from their input products, and these products can have different flag definitions. That means that the MER image bit flag values will have a different meaning depending on the filter assotiated to the mosaic. Read the VIS calibrated quad frame, NIR calibrated frame, and EXT stacked frame product documentation for more details about their specific image flag values.

Flags are propagated using an OR operation: it is enough that one of the input images had the flag switched on at the mosaic pixel position, to switch on the mosaic bit flag at that position.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	AUTHOR	Who ran the software (Swarp keyword)	string
	BITPIX	array data type	integer
	CD1_1	Linear projection matrix	double
	CD1_2	Linear projection matrix	double
	CD2_1	Linear projection matrix	double
	CD2_2	Linear projection matrix	double
	CENTERT1	CENTER_TYPE config parameter (Swarp keyword)	string
	CENTERT2	CENTER_TYPE config parameter (Swarp keyword)	string
	COMBINET	COMBINE_TYPE config parameter for SWarp (Swarp keyword)	string
	CRPIX1	Reference pixel on this axis	double
	CRPIX2	Reference pixel on this axis	double
	CRVAL1	World coordinate on this axis	double
	CRVAL2	World coordinate on this axis	double
	CTYPE1	WCS projection type for this axis	string
	CTYPE2	WCS projection type for this axis	string
	CUNIT1	Axis unit	string
	CUNIT2	Axis unit	string
	DATASETR	The pipeline data set release	string
	DATE	When it was started (GMT) (Swarp keyword)	string
	EQUINOX	Mean equinox	double
	EXTEND	This file may contain FITS extensions	logical
	FILTER	The filter name	string
	NAXIS	number of array dimensions	integer
	NAXIS1	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	NAXIS2	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	ORIGIN	Where it was done (Swarp keyword)	string
	PIPDEFID	The pipeline definition id	string
	PPLANID	The parent plan id	string
	PPOID	The pipeline processing order id	string
	PSCALET1	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSCALET2	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSWNAME	The pipeline software name	string
	PSWREL	The pipeline software release	string
	RADESYS	Astrometric system	string
	RESAMPT1	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	RESAMPT2	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	SIMPLE	conforms to FITS standard	logical
	SOFTAUTH	Maintainer of the software (Swarp keyword)	string
	SOFTDATE	Release date of the software (Swarp keyword)	string
	SOFTINST	Institute (Swarp keyword)	string
	SOFTNAME	The software that processed those data (Swarp keyword)	string
	SOFTVERS	Version of the software (Swarp keyword)	string

PSF FITS file

This FITS file stores the propagated PSF stamps for most of the sources in the MER final catalog.

The file consists of an image extension with all the PSF stamps distributed on a regular grid, and a table extension with the PSF stamps coordinates (RA, Dec), their central pixel position on the image extention (x_center, y_center) and on the mosaic image (x, y). The stamp size in pixel units, STMPSIZE, is stored in the header of the PSF image extension.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	BITPIX	array data type	integer
	EXTEND		logical
	NAXIS	number of array dimensions	integer
	SIMPLE	conforms to FITS standard	logical

PSF image extension header keywords:

Stamps information table columns:

Catalog: 7 columns table
Name	Description	Unit	Format
x_center		pix	FITS D
y_center		pix	FITS D
x		pix	FITS D
y		pix	FITS D
RA		deg	FITS D
Dec		deg	FITS D
FWHM		arcsec	FITS D

Filter transmission FITS file

This FITS file contains the average filter transmission wavelength for each pixel in the mosaic.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	AUTHOR	Who ran the software (Swarp keyword)	string
	BITPIX	array data type	integer
	CD1_1	Linear projection matrix	double
	CD1_2	Linear projection matrix	double
	CD2_1	Linear projection matrix	double
	CD2_2	Linear projection matrix	double
	CENTERT1	CENTER_TYPE config parameter (Swarp keyword)	string
	CENTERT2	CENTER_TYPE config parameter (Swarp keyword)	string
	COMBINET	COMBINE_TYPE config parameter for SWarp (Swarp keyword)	string
	CRPIX1	Reference pixel on this axis	double
	CRPIX2	Reference pixel on this axis	double
	CRVAL1	World coordinate on this axis	double
	CRVAL2	World coordinate on this axis	double
	CTYPE1	WCS projection type for this axis	string
	CTYPE2	WCS projection type for this axis	string
	CUNIT1	Axis unit	string
	CUNIT2	Axis unit	string
	DATASETR	The pipeline data set release	string
	DATE	When it was started (GMT) (Swarp keyword)	string
	EQUINOX	Mean equinox	double
	FILTER	The filter name	string
	NAXIS	number of array dimensions	integer
	NAXIS1	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	NAXIS2	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	ORIGIN	Where it was done (Swarp keyword)	string
	PIPDEFID	The pipeline definition id	string
	PPLANID	The parent plan id	string
	PPOID	The pipeline processing order id	string
	PSCALET1	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSCALET2	PIXELSCALE_TYPE config parameter (Swarp keyword)	string
	PSWNAME	The pipeline software name	string
	PSWREL	The pipeline software release	string
	RADESYS	Astrometric system	string
	RESAMPT1	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	RESAMPT2	RESAMPLING_TYPE config parameter (Swarp keyword)	string
	SIMPLE	conforms to FITS standard	logical
	SOFTAUTH	Maintainer of the software (Swarp keyword)	string
	SOFTDATE	Release date of the software (Swarp keyword)	string
	SOFTINST	Institute (Swarp keyword)	string
	SOFTNAME	The software that processed those data (Swarp keyword)	string
	SOFTVERS	Version of the software (Swarp keyword)	string

Layers FITS file

This FITS file stores relevant information (exposure time, observation date, spatial footprint) about all the VIS and NIR input images that contributed to the mosaic.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	BITPIX	array data type	integer
	EXTEND	This file may contain FITS extensions	logical
	NAXIS	number of array dimensions	integer
	SIMPLE	conforms to FITS standard	logical

Table columns:

Catalog: 8 columns table
Name	Description	Unit	Format
CALIB_IMAGE	Calibrated image file name	NA	FITS 80A
EXTNAME	Calibrated image extension name	NA	FITS 15A
EXPTIME	Exposure time	s	FITS 1E
POLYGON	Detector or quadrand spatial polygon	rad	FITS 8D
ALPHA	Alpha angle	NA	FITS 1E
BETA	Beta angle	NA	FITS 1E
SAA	Solar Aspect Angle	NA	FITS 1E
MJD-OBS	Instrument sequence start time in MJD	d	FITS 1E

Bright star masks json file

File containing the Gaia bright star masks point (RA, Dec) coordinates.

Background FITS file

FITS file containing the background model calculated in the MER background subtraction step.

This background has been subtracted to the mosaic image FITS file.

PRIMARY extension header keywords:

HDU PRIMARY: header
	Name	Description	Value
Keywords	BITPIX	array data type	integer
	CD1_1	Linear projection matrix	double
	CD1_2	Linear projection matrix	double
	CD2_1	Linear projection matrix	double
	CD2_2	Linear projection matrix	double
	CRPIX1	Reference pixel on this axis	double
	CRPIX2	Reference pixel on this axis	double
	CRVAL1	World coordinate on this axis	double
	CRVAL2	World coordinate on this axis	double
	CTYPE1	WCS projection type for this axis	string
	CTYPE2	WCS projection type for this axis	string
	CUNIT1	Axis unit	string
	CUNIT2	Axis unit	string
	DATASETR	The pipeline data set release	string
	EQUINOX	Mean equinox	double
	EXTEND	This file may contain FITS extensions	logical
	FILTER	The filter name	string
	NAXIS	number of array dimensions	integer
	NAXIS1	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	NAXIS2	NUMBER OF ELEMENTS ALONG THIS AXIS	integer
	PIPDEFID	The pipeline definition id	string
	PPLANID	The parent plan id	string
	PPOID	The pipeline processing order id	string
	PSWNAME	The pipeline software name	string
	PSWREL	The pipeline software release	string
	RADESYS	Astrometric system	string
	SIMPLE	conforms to FITS standard	logical

Image quality parameters

The following list of quality parameters is calculated for each MER mosaic image. Their values can be used to select an specific subset of background-subtracted mosaics, to study global trends, or to detect potencial problems in the MER pipeline or its input products.

Quality parameter	Descriptiom
Mean	Average image level (mean of all image pixel values)
Median	Median image level (estimated median of all image pixel values)
StDev	Sample standard deviation of the image pixel values
Min	Minimum image pixel value
Max	Maximum image pixel value
MaskedPixelFraction	The fraction of masked pixels
CoverageFraction	The fraction of the image covered with data

Background quality parameters

The following list of quality parameters is calculated for each MER mosaic backgroun map.

Quality parameter	Descriptiom
Mean	Average background level (mean of all background pixel values)
Median	Median background level (estimated median of all background pixel values)
StDev	Sample standard deviation of the background pixel values
Min	Minimum background pixel value
Max	Maximum background pixel value