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

__license__ = "Public Domain"

import ephem

# McNaught Xephem entry from
# http://cfa-www.harvard.edu/iau/Ephemerides/Comets/Soft03Cmt.txt
McNaught = ephem.readdb("C/2006 P1 (McNaught),h,01/12.7961/2007,77.8349,267.4144,155.9771,1.000019,0.170742,2000,6.0,4.0")

# 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