= Sunrise Sunset =
This class will determine the sunrise and sunset. It can use either '''official''', '''civil''', '''nautical''', '''amateur''', or '''astronomical''' zenith.

[[attachment:sunrisesunset.py]]

[[http://tetrasys.homelinux.org/cgi-bin/viewvc.cgi/sunrisesunset/?root=cvs|CVS Repository]] This is off site.

[[http:/wiki-htdocs/external/SunriseSunset/api/index.html|API Docs]]

[[http://tetrasys-design.net/download/SunriseSunset/sunrisesunset-1.0.1.tar.gz|Download Tarball]]

[[http://freshmeat.net/projects/sunrise-sunset|Freshmeat Page]]

The constructor takes three positional arguments and one keyword argument. The {{{date}}} argument is a datetime object with timezone info, {{{lat}}} and {{{lon}}} are floating point values, and {{{zenith}}} is a string consisting of any of the above bold values--the default is '''official'''.

{{{
ss = SunriseSunset(date, lat, lon, zenith='official')
}}}
There are two callable methods after the class is instantiated.

The {{{getSunRiseSet()}}} method returns a tuple of datetime objects with timezome info.

{{{
rise, set = ss.getSunRiseSet()
}}}
The {{{isNight()}}} method returns {{{True}}} if it is nighttime and {{{False}}} if it is daytime. The optional {{{collar}}} keyword argument if changed will skew the results to either before or after the real sunrise and sunset. This is useful if lead and lag times are needed around the actual sunrise and sunset.

{{{
isNight = ss.isNight(collar=0)
}}}
The formula was taken from a VBScript implementation which is broken for certain times of the day. It can be found at:

[[http://4guysfromrolla.com/webtech/010800-1.shtml|4 Guys From Rolla]]

I also found valuable information on these sites:

http://stjarnhimlen.se/english.html

http://aa.usno.navy.mil/faq/docs/RST_defs.php

http://herbert.gandraxa.com/herbert/lod.asp