def calcLSTrange(self):
"""
Returns the minimum and maximum LST from the position
and the minimum elevation (in radians).
"""
if self.ra is None or self.dec is None:
return (None, None)
# our utility tool - it takes everything in degrees
if self.elevation_min is not None:
h = Horizon(rad2deg(self.elevation_min))
else:
h = Horizon()
# and the tool returns DateTimeDelta's
rise, set = h.riseSetLSTs(rad2deg(self.ra)
, rad2deg(self.dec))
# unless this is a special case!
if set is None:
# our source never sets - it's always up!
return (0.0, hr2rad(24.0))
if rise is None:
# our source never rises
return (0.0, 0.0)
minLst = hr2rad(h.normalizeHours(rise))
maxLst = hr2rad(h.normalizeHours(set))
return (minLst, maxLst)
def test_getRiseSet(self):
now = DateTime.DateTime(2006, 5, 31, 18, 6, 4)
# default elevation limit
h = Horizon()
rise, set = h.riseSetLSTs(20.0, 20.0, now)
self.assertEqual('18:41:12.03', str(rise))
self.assertEqual('07:58:47.97', str(set))
# raise the el. limit and watch things rise later
# and set earlier
h = Horizon(20.0)
rise, set = h.riseSetLSTs(20.0, 20.0, now)
self.assertEqual('20:00:15.72', str(rise))
self.assertEqual('06:39:44.28', str(set))
# a lower dec should mean less time up
h = Horizon(20.0)
rise, set = h.riseSetLSTs(20.0, 0.0, now)
self.assertEqual('21:03:18.21', str(rise))
self.assertEqual('05:36:41.79', str(set))
# demonstrates that we need to normalize results
h = Horizon()
ra = rad2deg(hr2rad(22.0))
rise, set = h.riseSetLSTs(ra, 10.0, now)
self.assertEqual('15:54:14.83', str(rise))
# watch for > 24 hours
self.assertEqual('1:04:05:45.17', str(set))
self.assertAlmostEqual(28.0958, set.hours, 2)
self.assertAlmostEquals(4.09588185187, h.normalizeHours(set), 3)
# source that is always up
rise, set = h.riseSetLSTs(ra, 80.0, now)
self.assertTrue(set is None)
# source that is never up
rise, set = h.riseSetLSTs(ra, -80.0, now)
self.assertTrue(rise is None)
# but a source that is always up may not survive the el limit
h = Horizon(30)
elLimHr = rad2hr(deg2rad(30))
rise, set = h.riseSetLSTs(ra, 80.0, now)
self.assertTrue(set is not None)
