.. _NIRLargeFlat:

[to complete]  NIR Large Scale Flat (LargeFlat)
=====================

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

Data Product Name
__________________
.. DataProductNameStart

$PrintDataProductName

.. DataProductNameEnd

Data Product Custodian
_________________________________
.. DataProductCustodianStart

$PrintDataProductCustodian

.. DataProductCustodianEnd

Name of the Schema File
________________________
.. NameSchemaStart

$PrintSchemaFilename

.. NameSchemaEnd

Data Product Elements
______________________
.. DataProductElementsStart

$PrintDataProductElements

.. DataProductElementsEnd


Detailed Description of the Data Product
_________________________________________
.. DetailedDescStart

The **LargeFlat** frame corrects the NIR science frames for variations in pixel response to a flat illumination.
This Data Product is dedicated to track large scale variations, i.e. >100 pixels.

A LargeFlat frame for each filter is foreseen.

In addition, a set of metadata is used to describe the validity range and Quality Parameters.


Processing Element(s) creating/using the data product
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. PECreatorStart

The **LargeFlat** is created by the *NIR_SelfCalib_Pipeline* pipeline. This pipeline compare source fluxes extracted in
dedicated Self Calibration Field observations to derive large scale pixel flux variations together with detector by detector
offset tracked by the :ref:`NIRRelPhotoDetCalibration` Data Product.

The task responsible for the LargeFlat creation is **NIR_Compute** (under *NIR_SelfCalib* project).

.. PECreatorEnd


Processing function using the data product
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. PFUsingStart

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

It is applied by the **NIR_Apply** task (under *NIR_SelfCalib* project) inside the *NIR_ProcessField_Pipeline*.

.. PFUsingEnd

Data Product structure description
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. DataProductDescrStart

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
* **DataStorage**: Element that links to a FITS file containing the LargeFlat FITS file
* **QualityParams** (optional): List of Detector 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

.. DataProductDescrEnd


FITS file description
~~~~~~~~~~~~~~~~~~~~~
.. FITSFileDescriptionStart

The structure of the NIR LargeFlat is the same as the Science Image of the :ref:`NIRCalibratedFrame` with 16 x 3 layers, i.e. containing
median large field correction, RMS, and Data Quality flags for each detector.

Primary header
****************

The primary header contains keywords to identify FITS data type.

$PrintPrimaryHeader fit/euc-test-nir.xml nir.largeFlat

SCI Extension header
****************

The scientific header contains some basic image definition keywords.

$PrintExtensionHeader fit/euc-test-nir.xml nir.largeFlat SCI.n

.. FITSFileDescriptionEnd

.. DetailedDescEnd