The vimos_ima_twilight_flat recipe
===============================================================

.. data:: vimos_ima_twilight_flat

Synopsis
--------

Twilight flat combination for imaging

Description
-----------

vimos_ima_twilight_flat -- VIMOS twilight flat combine recipe.


Combine a list of twilight flat frames into a mean frame. Optionally
compare the output frame to a reference twilight flat frame

The program accepts the following files in the SOF:

    Tag                   Description
    FLAT_TWILIGHT         A list of raw twilight flat images
    MASTER_BIAS           A master bias frame
    MASTER_DARK           A master dark frame
    REFERENCE_TWILIGHT_FLAT Optional reference twilight flat frame
If no reference twilight flat is made available, then no comparison will be
done. This means there will be no output ratio image and no stats

Constructor
-----------

.. method:: cpl.Recipe("vimos_ima_twilight_flat")
   :noindex:

   Create an object for the recipe vimos_ima_twilight_flat.

::

   import cpl
   vimos_ima_twilight_flat = cpl.Recipe("vimos_ima_twilight_flat")

Parameters
----------

.. py:attribute:: vimos_ima_twilight_flat.param.lthr

    Low rejection threshold for underexpsed images (float; default:  4000.0) [default=4000.0].
.. py:attribute:: vimos_ima_twilight_flat.param.hthr

    High rejection threshold for overexposed images (float; default:  60000.0) [default=60000.0].
.. py:attribute:: vimos_ima_twilight_flat.param.combtype

    Combination algorithm (str; default: 'median') [default="median"].
.. py:attribute:: vimos_ima_twilight_flat.param.scaletype

    Scaling algorithm (str; default: 'multiplicative') [default="multiplicative"].
.. py:attribute:: vimos_ima_twilight_flat.param.xrej

    True if using extra rejection cycle (bool; default: True) [default=True].
.. py:attribute:: vimos_ima_twilight_flat.param.thresh

    Rejection threshold in sigma above background (float; default: 5.0) [default=5.0].
.. py:attribute:: vimos_ima_twilight_flat.param.ncells

    Number of cells for diff image stats (int; default: 8) [default=8].
.. py:attribute:: vimos_ima_twilight_flat.param.prettynames

    Use pretty output file names? (bool; default: False) [default=False].


The following code snippet shows the default settings for the available 
parameters.

::

   import cpl
   vimos_ima_twilight_flat = cpl.Recipe("vimos_ima_twilight_flat")

   vimos_ima_twilight_flat.param.lthr = 4000.0
   vimos_ima_twilight_flat.param.hthr = 60000.0
   vimos_ima_twilight_flat.param.combtype = "median"
   vimos_ima_twilight_flat.param.scaletype = "multiplicative"
   vimos_ima_twilight_flat.param.xrej = True
   vimos_ima_twilight_flat.param.thresh = 5.0
   vimos_ima_twilight_flat.param.ncells = 8
   vimos_ima_twilight_flat.param.prettynames = False


You may also set or overwrite some or all parameters by the recipe 
parameter `param`, as shown in the following example:

::

   import cpl
   vimos_ima_twilight_flat = cpl.Recipe("vimos_ima_twilight_flat")
   [...]
   res = vimos_ima_twilight_flat( ..., param = {"lthr":4000.0, "hthr":60000.0})


.. seealso:: `cpl.Recipe <https://packages.python.org/python-cpl/recipe.html>`_
   for more information about the recipe object.

Bug reports
-----------

Please report any problems to `Jim Lewis <jrl@ast.cam.ac.uk>`_. Alternatively, you may 
send a report to the `ESO User Support Department <usd-help@eso.org>`_.

Copyright
---------

This file is part of the VIMOS Instrument Pipeline
Copyright (C) 2019 European Southern Observatory

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, 
MA  02111-1307  USA

.. codeauthor:: Jim Lewis <jrl@ast.cam.ac.uk>