README file for Python module stars
-----------------------------------

Module stars defines a class called Star which is essentially a
placeholder for the following information about stars:

name                ---           Consist of a catalog name + id
ra                  ---           right ascension (decimal degrees)
dec                 ---           declination (decimal degrees)
sra                 ---           right ascension uncertainty (arcseconds)
sdec                ---           declination uncertainty (arcseconds)
x, y                ---           rectangular coordinates after TAN projection
u, b, v, r, i       ---		  magnitudes for UBVRI filters
su, sb, sv, sr, si  ---           magnitude uncertainties for UBVRI filters

If any value is missing in the catalog, it is replaced by -99, so the
application program can check for existence of this value.

The Star class has defined __str__ method which is invoked in a
command like "print star".  All star parameters are neatly printed in
a single line and are suitable for processing with awk, perl, python,
C, fortran, etc.

There is another class, called Catalog.  In the instantiation you
specify 2 parameters:  catalog type, which is currently one of
(PHOTOM, GSC, USNO and ACT) and a path to the catalog.  This class has
a method called get_stars with the following arguments:

ra     Right ascension in decimal degrees
dec    Declination in decimal degrees
width  Field width in decimal degrees (default 1.0)
height Field height in decimal degrees (default 1.0)
fi     Field rotation in decimal degrees (default 0.0)
imw    Image width in pixels
imh    Image height in pixels
minmag minimal magnitude
maxmax maximal magnitude

A minimal program which reads stars around coordinate ra=01:00:00,
dec=-16:00:00 from the GSC catalog looks like this:

--------------------------Program starts in the next line--------------
from stars import *
#  You will need to set your own path to GSC
gsc = Catalog('GSC', '/home/jure/astro/katalogi/gsc')
stars = gsc.get_stars(15, -16)
for a in stars:
    print a
---------------------Program ended in the previous line-----------------

Probably it can't go much shorter and easier.


CATALOGS:

This module supports the following catalogs:

GSC 1.1 (hint: If you have on a CD, copy it to the hard disk and compress 
	catalog files with gzip)
USNO A1.0, SA1.0, A2.0, SA2.0
ACT     in a binary form made with program makeact by J. Skvarc
PHOTOM  compilation of photometric standard catalogs prepared by
	A. Henden (USNO) and B. Skiff (LONEOS)