.. C-Munipack - User's manual

   Copyright 2012 David Motl

   Permission is granted to copy, distribute and/or modify this document under the
   terms of the GNU Free Documentation License, Version 1.2 or any later version published
   by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and
   no Back-Cover Texts.

   $Id: match_stars_dialog.rst,v 1.2 2012/09/01 12:47:00 dmotl Exp $

.. index::
   pair: Match stars; dialog
   
.. _match-stars-dialog:

Match stars (dialog)
====================

The "Match stars" dialog is used to select a frame that shall be used during the matching process
as a reference. The matching process finds corresponding stars on each source frame with respect to
the reference frame.


Activating the dialog
---------------------

The dialog can be activated:

.. |matchstars_icon| image:: ../../share/icons/matchstars.png

#. from the main menu: :menuselection:`Reduce --> Match stars`.

#. from the main toolbar: |matchstars_icon|


Reference frame vs. catalog file
--------------------------------

There are two possibilities:

#. To pick one frame out of the source frame and use it as a reference. This frame is
   then referred to as a reference frame. There is no simple rule which frame you shall choose,
   selecting a frame with the greatest number of measured objects is usually a good starting
   point, though. The important idea is that the program can deal with a situation when a measured
   object is not present on all frames, but it must be present on a reference frame. Thus,
   make sure that at least the variable star and the comparison star are present of a reference
   frame.
   
#. To use a catalog file that has been made during processing of previous run of the
   same field. When you observe a particular variable star on regular basis, it's tedious
   to manually select stars and enter the position for every run. Utilizing the catalog
   files makes it simpler, because the application restores the information from a persistent
   file.
   
.. index::
   pair: Reference; frame
   
Selecting a reference frame
---------------------------

.. figure:: images/matchstars_couts1.png
   :align: center
   :alt: Match stars dialog
   
   The dialog for selecting a reference frame

Check the option (1). The list of valid source frames is displayed here (2).

\(3) When you select a frame, the preview and short info is displayed here. Double
click on the preview to show a larger preview in a separate dialog.

Select a frame.

Click the "Execute" button (4) to start the matching.

.. index::
   pair: Catalog; file

Browsing the catalog files
--------------------------

.. figure:: images/matchstars_couts2.png
   :align: center
   :alt: Match stars dialog
   
   The dialog for selecting a catalog file

Check the option (10). The list of predefined catalog files is displayed here (11).

\(12) You can change the folder in which the files are looked for.

\(13) When you select a frame, the preview and short info is displayed here. Double
click on the preview to show a larger preview in a separate dialog.

Select a file. It is recommended to use a file that was carried out with the same color
filter as your source files, this is not required, though.

Click the "Execute" button (14) to start the matching.


Executing the matching
----------------------

Click the "Execute" button to start the matching.

- The photometry must be applied before the matching.

- The matching can be applied several times, the old cross-reference data are overwritten.


.. seealso:: :ref:`make-catalog-file-dialog`, :ref:`photometry-dialog`