Shear Intermediate Euclidized HST Images product

Data product name

sheIntermediateEuclidizedHstImages

Data product custodian

SHE

Data model tag

8.0

Name of the Schema file

ST_DM_Schema/dictionary/pro/she/euc-test-she.xsd

Schema documentation tag

Documentation for data product element sheIntermediateEuclidizedHstImages:

This product contains a set of Euclidized HST images required for calibration of the shear measurement methods, at an intermediate processing stage.

Documentation for data product element Header:

The generic header of the product.

Data product elements

• ValidityRange (ins:calibrationValidPeriod)

• EuclidizedHstObjectList (sheEuclidizedHstObject)

• sheEuclidizedHstObject 1

• DataStorage (dss:dataContainer)

• PsfStorage (dss:dataContainer)

• sheEuclidizedHstObject 2

• DataStorage (dss:dataContainer)

• PsfStorage (dss:dataContainer)

• …

Processing Element(s) creating/using the data product

SHE_HSTCalibration

Processing function using the data product

SHE

Detailed description of the data product

In its final stage, this product contains a catalogue of postage stamps of galaxies that fulfil a given set of search criteria and which are required for the calibration of the shear measurement methods. The catalogue will provide metadata for these galaxies. It is joined by FITS files of the Euclidized HST postage stamp images of the galaxes themselves and FITS images of the respective PSFs for the galaxy images as derived from the HST exposures.

An intermediate stage provides the full-size FITS images of the reduced HST exposures, each paired with a FITS image of the derived PSFs for these exposures.

In order to produce the final stage products, the reduced HST exposures are supposed to be injected into the OU-EXT AstroWISE database, subsequently processed by existing OU-MER PFs for Euclidization, and finally Euclidized postage stamps are re-extracted using OU-MER’s object detection algorithms on the set of selection criteria.

This way, a set of postage stamp images of galaxies of defined properties is produced which look like they would appear if observed by Euclid, complying with the actual OU-MER selection criteria.

Intermediate calibration algorithms can relate to the full-size HST frames directly, however.

Intermediate Stage Products

• Each reduced HST exposure is provided as a FITS MEF file, of the following format:

  HDU

  Header

  The header will contain the originary HST FITS MEF metadata, plus some added information on the reduction steps in the comments section.

  Data

  The data will contain the usual 6 MEF extensions of an HST FITS image file, which are for each of the two HST CCDs the scientific image (SCI), the error field (ERR) and the data quality field (DQ).

• The associated FITS file containing the derived PSF will be of the following format:

  HDU

  Header

  Parameter name	Fits Data type	Brief description
  ROOTNAME	A32	Rootname of the HST observation set
  VERS_PSF	A8	Version of the reduction code used in extracting the PSFs
  GRID_X	I	Grid size (PSF centers) in X dimension
  GRID_Y	I	Grid size (PSF centers) in Y dimension
  META_i	TBD	Set of further metadata for the PSF

  Data

  Data will provide a 2D floating point image extension for each of the two HST CCDs, containing a grid of PSFs determined for the associated HST exposure.