#! /usr/bin/python
"""Output an ephemeris for comet McNaught around the height of
its visibility around James' location."""

__license__ = "Public Domain"

import ephem

# McNaught body generated using content from
# http://www.aerith.net/comet/catalog/2006P1/2006P1.html
McNaught = ephem.HyperbolicBody()
McNaught.name = 'C/2006 P1 ( McNaught )'
McNaught._epoch = '2007/01/20.0'
McNaught._epoch_p = '2007/01/12.79895'
# Defined in the page as simply "incl"
McNaught._inc = 77.83694
# Defined in the page as "Node"
McNaught._Om = 267.41500
# Defined in the page as "Peri"
McNaught._om = 155.97648
# Both "e" and "q" are used on the page
McNaught._e = 1.0000135
McNaught._q = 0.1707278
# Calculated magnitude properties from the page's magnitude equations
McNaught._g = 6.0
McNaught._k = 4.0

# We are also going to calculate sun rise/set times to allow estimation of
# visibility on a given day.
Sun = ephem.Sun()

# Location for my house :)  Approximately, 50 kilometres south west of
# Cambridge, UK.  For all intents and purposes elevation is entirely
# redundant for these calculations, and can be ignored.  The
# accuracy expressed in the latitude and longitude values are also
# neither required, nor particularly useful outside of being a good
# example of false precision.  I just happen to have the information
# to hand in this format from my FOAF file.
home = ephem.Observer()
home.lat, home.long, home.elev = '52.015', '-0.221', 60.0

home.date = ephem.date('2007/1/5')
for i in range(10):
    McNaught.compute(home)
    Sun.compute(home)
    print "%i-%02i-%02i" % home.date.tuple()[:3]
    # Only display McNaught rise times *before* the Sun rises
    if McNaught.rise_time.tuple() < Sun.rise_time.tuple():
        print "  > McNaught rises @", str(McNaught.rise_time).split(" ")[1]
        print "  > Sun rises      @", str(Sun.rise_time).split(" ")[1]
        duration = (Sun.rise_time - McNaught.rise_time) / ephem.minute
        print "  > Duration         %0i minutes" % duration
    # Only display McNaught set times *after* the Sun sets
    if McNaught.set_time.tuple() > Sun.set_time.tuple():
        print "  < Sun sets       @", str(Sun.set_time).split(" ")[1]
        print "  < McNaught sets  @", str(McNaught.set_time).split(" ")[1]
        duration = (McNaught.set_time - Sun.set_time) / ephem.minute
        print "  < Duration         %0i minutes" % duration
    home.date += 1