[to complete] NIR Absolute Photometric Calibration Factors

$SetSchemaPath nir/euc-test-nir-RelPhotoDetCalibration.xsd

Data Product Name

$PrintDataProductName

Data Product Custodian

$PrintDataProductCustodian

Name of the Schema File

$PrintSchemaFilename

Data Product Elements

$PrintDataProductElements

Detailed Description of the Data Product

The DpdNirAbsPhotoCalibration data contains absolute photometric calibration parameters, to convert input data to physical units.

This is a “pure” xml Data Product that contains the inverse sensitivity value.

A DpdNirAbsPhotoCalibration for each filter is foreseen.

It is structured with a set of metadata to define absolute photometric parameters and validity range.

Processing Element(s) creating/using the data product

The DpdNirAbsPhotoCalibration is created by the NIR_AbsolutePhotometry_Pipeline.

This pipeline compares “white dwarf” fluxes, extracted in dedicated observations, to derive an inverse sensitivity constant, which can be used to convert from electrons per second (e/s) to microJanskys (μJy). In addition to computing the inverse sensitivity, zero points for converting to AB magnitude and Vega magnitude are provided (ZPAB and ZPVEGA, respectively). Uncertainties are reported for all quantities.

The task responsible for the DpdNirAbsPhotoCalibration creation is NIR_ComputeAbsolutePhotometry (under NIR_AbsolutePhotometry project).

Processing function using the data product

This is an internal NIR data product, and it is used only by the NIR PF.

It is applied by the NIR_ApplyAbsolutePhotometry task (under NIR_AbsolutePhotometry project) inside the NIR_ProcessField_Pipeline.

The task writes the inverse sensitivity constant on PHOTFNU keyword. In combination with relative photometric keywords it can be used to convert from native image units to absolute flux, in μJy.

flux_in_microJy = PHOTFNU x PHRELEX x PHRELDT x pixel_value

Data Product structure description

The main elements inside the Data section are:

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

  • ValidityRange: Calibration file validity period estimated

  • StandardStar: Name of Standard Star used for calibration

  • CalibrationWavelength: Calibration Wavelength

  • CentralWavelength: Central Wavelength

  • HalfPowerBandwidth: Half Power Bandwidth

  • InverseSensitivity: Inverse Sensitivity

  • VegaMagnitude: Vega Magnitude