NIR Stacked Frame

Metadata

Data product name

DpdNirStackedFrame

Data product custodian

NIR

Name of the Schema file

euc-nir-StackedFrame.xsd

Last Edited for DPDD Version

1.1

Processing Element(s) creating/using the data product

Creators:

  • NIR

The DpdNirStackedFrame data product components are created by different tasks during the execution of the NIR_ProcessField_Pipeline:

  • The MEF file is created by the NIR_DostackProgram task of the NIR_Stacking

project * The PSF model and image are created by the NIR_PSFModelling task of the NIR_PointSpreadFunction project * The data product xml is written by the final NIR_ProcessField_Pipeline step that is NIR_CreateScientificDpds of NIR_Utilities project

Consumers:

  • NIR

Into the NIR_ProcessField_Pipeline the MEF file is used as input for the NIR_CatalogExtraction PE to create the NIR Stacked Frame Catalog containing source extracted.

Processing function using the data product

Indicate here the PF you are aware of using the product. Can be the custodian PF itself for internal product. Can also be Science Working Group for final products. The list does not need to be exhaustive.

This is one of the output of the NIR_ProcessField_Pipeline.

In the pipeline the MEF file is used as input for the NIR_CatalogExtraction PE to create the NIR Stacked Frame Catalog with source extracted.

  • PF-NIR

Proposed for inclusion in EAS/SAS

This product is proposed for inclusion in the SAS: yes

Data Product Elements

Header

object of type sys:genericHeader

Data

object of type nir:nirStackedFrame

QualityFlags

object of type dqc:sqfPlaceHolder

Parameters

object of type ppr:genericKeyValueParameters

Detailed Description of the Data Product

The DpdNirStackedFrame is one of the output of the NIR_ProcessField_Pipeline applied to wide survey observations and in general to “scientific” pointings (i.e. Self Calibration).

It is the result of the stacking process of a set of input images, 4 in case of wide, the nominal survey strategy. It could be created also in some specific cases with more exposures. A single stacked image is provided at the end of each NIR_ProcessField_Pipeline run.

../../_images/nirStackedFrame.png

Fig. 25 : Graphical representaton of Data section structure for DpdNirStackedFrame

The main elements inside the Data section are:

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

  • WCS: The description of the WCS for the image. This field mirrors values in the FITS header

  • ZeroPoint: The effective photometric zero point of this stack of single images

  • ImgSpatialFootprint: This spatial area defines the spatial footprint of the image in a series of vertex

  • ObservationId: Image Observation Id

  • TargetPointing: Coordinates of target pointing

  • DataStorage: FITS file name containing the Stacked image FITS file

  • PsfStorage: Reference to the PSF files (Model and FITS)

  • QualityParams (optional):Data Quality Parameters

    • Min: Minimum image pixel value

    • Max: Maximum image pixel value

    • Mean: Average image level (mean of all image pixel values)

    • Median: Median image level (median of all image pixel values)

    • StDev: Sample standard deviation of the image pixel values

    • MaskedPixelFraction: The fraction of masked pixels

The DpdNirStackedFrame data product contains the link to 3 files:

  • a MEF file with the science image

  • a PSF model measured from science frames

  • a PSF image of the model

Scientific image FITS file

The main result of the stacking process is a MEF file stored into the DpdNirStackedFrame in the Data.DataStorage field.

The file is composed by four layers:

Layer name

Data Format

Units

Content

PRIMARY

Main headers

SCI

float32

microJy

Scientific data

RMS

float32

microJy

RMS data

DQ

int32

Data Quality mask
../../_images/stacked_frame.png

Fig. 26 : Graphical representation of 3-layer structure of NIR stacked frames

Primary layer

The primary layer is an header dedicated to store global infomation on pointings and parameters used by SWarp for resampling and stacking (i.e. starting from COMBINET, RESAMPT1 up to PSCALET2 in the next table) together with the inverse sensitivity value PHOTFNU needed to convert pixels in [microJy].

HDU PRIMARY: header

Name

Description

Value

Keywords

FITS_DEF

FITS name definition

string = nir.stackedImage

FITS_VER

FITS version

string = 0.3

TELESCOP

string = Euclid

INSTRUME

or NISPsim for simulations

string = NISP

VERSION

Data Release version

string

DATE

UT date when this file was created

string

IMG_CAT

ImgType:Category DP category (SCIENCE, CALIB, …)

string

IMG_T1

ImgType:FirstType DP type (OBJ, SRD, DARK, …)

string

IMG_T2

ImgType:SecondType DP type (LAMP, SKY, …)

string

OBSMODE

ImgType:ThirdType DP type (WIDE, DEEP, CALIBRATION)

string

OBSTYPE

ImgType:Technique DP technique (IMAGE, SPECTROIMAGE)

string

OBS_ID

eso:observationSequence:ObservationId Running Sequence number of the Observed block

integer

FILTER

Filter name, e.g. NIR_J

string

DATE_STA

DateRange:TimestampStart Observation Date first dither

string

DATE_END

DateRange:TimestampEnd Observation Date last dither

string

RA

TargetPointing:RA Center of field of view right ascension (deg)

double

DEC

TargetPointing:DEC Center of field of view right declination (deg)

double

PA

TargetPointing:Orientation Position angle (deg)

double

EQUINOX

Standard FK5 (years), e.g. 2000.

double

RADESYS

Coordinate reference frame, e.g. FK5

string

EXPTIME

ExposureTime Effective integration time in seconds, e.g. 60.0005

double

COMBINET

COMBINE_TYPE config parameter for SWarp

string

RESAMPT1

RESAMPLING_TYPE config parameter

string

CENTERT1

CENTER_TYPE config parameter

string

PSCALET1

PIXELSCALE_TYPE config parameter

string

RESAMPT2

RESAMPLING_TYPE config parameter

string

CENTERT2

CENTER_TYPE config parameter

string

PSCALET2

PIXELSCALE_TYPE config parameter

string

CAL_VER

version of calibration factors

double

WAVE_CAL

wavelength used for calibration microns

double

WAVELEN

central wavelength of bandpass microns

double

WAVEHPBW

half power bandwidth microns

double

PHOTFNU

inverse sensitivity Jy s / e

double

PHOTFNUE

error in PHOTNU Jy s / e

double

Scientific Layer

The scientific layer, named SCI, stores the data obtained combining togheter all images used as input to the NIR Pipeline.

The header contains some basic image definition keywords together with the GAIN and the SATURATE keywords derived by SWarp for resampling and stacking.

HDU DETn.SCI: header

Name

Description

Value

Keywords

EXTNAME

e.g. DET11.SCI, meaning Detector number 0, Science data

string

DET_ID

Detector:DetectorId e.g. Detector ID, e.g. 11

string

BITPIX

array data type

integer

NAXIS

e.g. number of array dimensions

integer

NAXIS1

e.g. pixel numbers on first axis

integer

NAXIS2

e.g. pixel numbers on second axis

integer

BUNIT

physical units of the array values

string

RPIX_PRC

Reference Pixel processing mode (0=no_px_correction,1=horiz_px_correction,2=vertical_px_correction)

integer

GAIN

Detector:Gain e- to ADU conversion factor, e.g. 1.5

double

EQUINOX

Standard FK5 (years), e.g. 2000.

double

RADESYS

Coordinate reference frame, e.g. FK5

string

CRVAL1

Right ascension at ref pixel

double

CRVAL2

Declination at ref pixel

double

CRPIX1

Reference pixel x coordinate

double

CRPIX2

Reference pixel y coordinate

double

CTYPE1

Coordinate 1 type

double

CTYPE2

Coordinate 2 type

double

CUNIT1

Axis 1 unit

string

CUNIT2

Axis 2 unit

string

CD1_1

Translation matrix element

double

CD1_2

Translation matrix element

double

CD2_1

Translation matrix element

double

CD2_2

Translation matrix element

double

PV1_0

Projection distortion parameter

double

PV1_1

Projection distortion parameter

double

PV1_2

Projection distortion parameter

double

PV1_4

Projection distortion parameter

double

PV1_5

Projection distortion parameter

double

PV1_6

Projection distortion parameter

double

PV1_7

Projection distortion parameter

double

PV1_8

Projection distortion parameter

double

PV1_9

Projection distortion parameter

double

PV1_10

Projection distortion parameter

double

PV2_0

Projection distortion parameter

double

PV2_1

Projection distortion parameter

double

PV2_2

Projection distortion parameter

double

PV2_4

Projection distortion parameter

double

PV2_5

Projection distortion parameter

double

PV2_6

Projection distortion parameter

double

PV2_7

Projection distortion parameter

double

PV2_8

Projection distortion parameter

double

PV2_9

Projection distortion parameter

double

PV2_10

Projection distortion parameter

double

ASTIRMS1

Astrom. dispersion RMS (intern., high S/N)

double

ASTIRMS2

Astrom. dispersion RMS (intern., high S/N)

double

ASTRRMS1

Astrom. dispersion RMS (ref., high S/N)

double

ASTRRMS2

Astrom. dispersion RMS (ref., high S/N)

double

ZPAB

zero point for conversion to AB magnitude

double

ZPABE

error in ZPAB determination

double

ZPVEGA

zero point for conversion to Vega magnitude

double

ZPVEGAE

error in ZPVEGA determination

double

PHRELDT

Correction factor for relative photometric calibration for detector

double

PHRELDTE

Uncertainty in PHRELDT

double

CRSNGALG

Algorithm used in finding cosmic rays

string

CRMULALG

Algorithm used in finding cosmic rays

string

DARKFILL

Dark fill value in e-

double

NBADPIXT

Number of bad pixels for detector

integer

NREJNL

Number of high noise pixels not corrected for non-linearity

integer

NSATPIX

Number of pixels flagged for saturation

integer

NDFILL

Number of high noise pixels with filled dark values

integer

NCRPIXS

Number of pixels masked as CR pixels in the single frame rejection

integer

NCRPIXM

Number of pixels masked as CR pixels in the multi frame rejection

integer

RMS Layer

The RMS layer is

DQ Layer

The DQ layer is

PSF files description

The Point Spread Function (PSF) is measured from the image. It is provided into two formats: a .psf file containing model parameters and a .fits file with an instance of model.

A PSF model is extracted from the scientific image by PSFEx software. This solution is provided both as model and as image.

The PSF model is produced as .psf file, an Astromatic format that can be directly provided to SExtractor for catalogue extraction. The model can track wavelength and focal plane position dependencies.

The PSF image is a FITS file with a primary and a single data layer containing a PSF image.

PSF Model file

This is a model file

PSF image file

The PSF primary header contains information on Observation Id in OBS_ID.

Because of the FITS structure is in common with the one used on NIR Calibrated Frame definition some keywords are meaning-less in case of stacked frame. As in example DITHOBS could be ignored and PSFTYPE is fixed to “Inflight” value because the PSF is always extracted from images.