Doc: Added preliminary table with a list of measurements.

.. File Param.rst

The catalog parameter file

============================

In addition to the configuration file detailed above, |SExtractor| requires a

file containing the list of parameters that will be listed in the output

catalog for every detection. This allows the software to compute only

catalog parameters that are needed. The name of this

catalog-parameter file is traditionally suffixed with ``.param``, and must

The measurement (or catalog) parameter file

===========================================

In addition to the configuration file detailed above, |SExtractor| requires a file containing the list of measurements ("catalog parameters") that will be listed in the output catalog for every detection. This allows the software to compute only the measurements that are needed. The name of this catalog parameter file is traditionally suffixed with ``.param``, and must

be specified using the ``PARAMETERS_NAME`` config parameter. The full set

of parameters can be queried with the command

_SKY, _J2000, _B1950

  Measurements are given in celestial (equatorial) coordinates, converted from pixel coordinates using the local Jacobian of the transformation between both systems. Positions and distances are in units of degrees. This requires celestial |WCS| metadata :cite:`2002AA_395_1077C` to be present in the FITS image header(s). _SKY measurements are given in the native world coordinate system. _J2000 and _B1950 measurements are automatically converted from the native |WCS|, taking into account the change of reference frame. In all cases, positions angles are counted East-of-North.

Measurement parameter list

--------------------------

Below is an exhaustive list of all the measurement parameters known to

|SExtractor|. Please refer to the next sections for a detailed description

of their meaning.

.. csv-table:: |SExtractor| measurement parameters

  :header: "Name", "Unit", "Description"

  :widths: 15 10 30

  NUMBER,, Running object number

  ID_PARENT,..., Parent ID (before deblending)

  EXT_NUMBER,..., FITS extension number

  :ref:`FLUX_ISO<flux_iso>`, count, Isophotal flux

  :ref:`FLUXERR_ISO<flux_iso>`, count, RMS error estimate for isophotal flux

.. include:: keys.rst

   {\tt MAGERR} = \frac{2.5}{\ln 10}\frac{\tt FLUXERR}{\tt FLUX}

.. _FLUX_ISO:

Isophotal flux

--------------

PHOT\_AUTOPARAMS; by default, PHOT\_AUTOPARAMS is set to 2.5,3.5.

.. figure:: ps/simlostflux.ps

   :alt:  Flux lost (expressed as a mean magnitude difference) with

   different faint-object photometry techniques as a function of total

   magnitude (see text). Only isolated galaxies (no blends) of the

   simulations have been considered.

   :alt:  Flux lost (expressed as a mean magnitude difference) with different faint-object photometry techniques as a function of total magnitude (see text). Only isolated galaxies (no blends) of the simulations have been considered.

   :width: 15.00000cm

   Flux lost (expressed as a mean magnitude difference) with different

================================================================

The following parameters are derived from the spatial distribution

:math:`\cal S` of pixels detected above the analysis threshold (see :ref:`description<isophotal_measurements>`). *Unless otherwise noted,

pixel values* :math:`I_i` *are taken from the (filtered) detection image*.

:math:`\cal S` of pixels detected above the analysis threshold (see :ref:`description<isophotal_measurements>`).

.. important::

  Unless otherwise noted, pixel values :math:`I_i` are taken from the (filtered) detection image.

.. note::

  Unless otherwise noted, all parameter names given below are only prefixes. They must be followed by _IMAGE if the results shall be expressed in pixel coordinates or _WORLD, _SKY, _J2000 or _B1950 for |WCS|_ coordinates (see :ref:`coord_suffix`).