.. _SPEintro:

Introduction
============

The SPE :term:`Processing Function` is in charge of measuring the spectroscopic redshift 
of astronomical objects observed with the NISP spectrograph. In addition to the redshift, 
a measure of the flux of the main emission lines and other several spectral features is performed.
To complete the process, an estimate of the accuracy and reliability of the measurements will be 
provided.

A classification is also given to disciminate astronomical source between stars, galaxies or QSO.

Inputs to the SPE :term:`Pipeline` are 1D combined spectra provided by the SIR Processing Function. 
This SIR product is defined over one MER tile (as defined by MER Processing Function).

The SPE Processing Function produces the :ref:`SPEPfOutputCatalog`. This SPE product is defined over one MER tile.

List of SPE Data Products
-------------------------

It is possible to identify two SPE Data Products types:  

- The **SPE Output Data Product** as result of the pipeline execution over a MER tile 
- The **SPE Internal Data Products** used for internal/technical purpose


SPE Output Data Product
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

==================================== ================================= ==========================
Data Product                           Ddp Name                         Description
==================================== ================================= ==========================
:ref:`SPEPfOutputCatalog`            `DpdSpePfOutputCatalog`           Redshift and lines catalog
==================================== ================================= ==========================

.. _SPEPipeline: 

SPE Pipeline
------------

The SPE pipeline fits QSO, star and galaxy spectrum models on input spectrum by using
several continuum templates. A line model is also used for galaxy modeling. Up to 5 
Redshift solutions is estimated. The reliability of the Redshift estimate is compute 
with deep learning algorithm and then spectral features are measured.

The SPE pipeline is massively parallelized by splitting the set of input spectra in 
several spectrum bunches.

A validation process ends the pipeline.

.. _SPE_preproc:
.. figure:: ./figures/PFSPE_section5.3_diag_act_v4.2.png

    SPE PF pipeline overview