def _get_ra_target_intervals(self, target, up, airmass, effective_horizon):
star = Star(self.site['latitude'], target, effective_horizon)
if up:
day_interval_func = self._find_when_target_is_up
else:
day_interval_func = self._find_when_target_is_down
# Find rise/set/transit for each day
intervals = []
current_date = self.start_date
while current_date < self.end_date + ONE_DAY:
one_day_intervals = day_interval_func(target, current_date, star,
airmass)
# Add today's intervals to the accumulating list of intervals
intervals.extend(one_day_intervals)
# Move on to tomorrow
current_date += ONE_DAY
# Collapse adjacent intervals into continuous larger intervals
intervals = coalesce_adjacent_intervals(intervals)
intervals = intersect_intervals(intervals,
[(self.start_date, self.end_date)])
return intervals
def get_ha_intervals(self, target):
"""Returns the hour angle intervals for the given target.
Returns the hour anle intervals for the given target and given site and date range set in this visibility object.
The hour angle intervals are uninterupted chunks of time that the target is within the hour angle limits of the
telescope.
Args:
target (dict): A dictionary of target details in the rise-set library format
Returns:
list: A list of tuples of start/end datetime pairs that make up the intervals over which this target is within HA limits.
"""
SIDEREAL_SOLAR_DAY_RATIO = 1.002737909350
SIDEREAL_SOLAR_DAY = datetime.timedelta(
seconds=(ONE_DAY.total_seconds() / SIDEREAL_SOLAR_DAY_RATIO))
earliest_date = self.start_date - SIDEREAL_SOLAR_DAY
tdb = date_to_tdb(earliest_date)
mjd = gregorian_to_ut_mjd(earliest_date)
gmst = ut_mjd_to_gmst(mjd)
# Need the apparent ra/dec for getting correct ha limits on high dec targets
apparent_ra, apparent_dec = mean_to_apparent(target, tdb)
# Flip the neg/pos ha limits if site is in the southern hemisphere
ha_neg = self.ha_limit_neg
ha_pos = self.ha_limit_pos
if self.site['latitude'].in_degrees() < 0:
ha_neg = -self.ha_limit_pos
ha_pos = -self.ha_limit_neg
# the rise time
hour_rise = ha_neg + apparent_ra.in_hours() - \
self.site['longitude'].in_hours() - gmst.in_hours()
hour_rise /= SIDEREAL_SOLAR_DAY_RATIO
# the set time
hour_set = ha_pos + apparent_ra.in_hours() - \
self.site['longitude'].in_hours() - gmst.in_hours()
hour_set /= SIDEREAL_SOLAR_DAY_RATIO
current_rise = earliest_date + datetime.timedelta(hours=hour_rise)
current_set = earliest_date + datetime.timedelta(hours=hour_set)
# Find hour angle limits for each day
intervals = []
while current_set < (self.end_date + SIDEREAL_SOLAR_DAY):
intervals.append((current_rise, current_set))
current_rise += SIDEREAL_SOLAR_DAY
current_set += SIDEREAL_SOLAR_DAY
# do not exceed start/end dates
intervals = coalesce_adjacent_intervals(intervals)
intervals = intersect_intervals(intervals,
[(self.start_date, self.end_date)])
return intervals
def test_intersect_case09(self):
# case 9 |......|
# |......|
expected = []
int1 = [(datetime.datetime(2013, 6, 15, 12, 0, 0),
datetime.datetime(2013, 6, 15, 15, 0, 0))]
int2 = [(datetime.datetime(2013, 6, 15, 15, 0, 0),
datetime.datetime(2013, 6, 15, 18, 0, 0))]
received = intersect_intervals(int1, int2)
assert_equal(received, expected)
def test_intersect_case12(self):
# case 12 |......|
# |...| |....|
expected = [(datetime.datetime(2013, 6, 15, 12, 0, 0),
datetime.datetime(2013, 6, 15, 13, 0, 0)),
(datetime.datetime(2013, 6, 15, 14, 0, 0),
datetime.datetime(2013, 6, 15, 15, 0, 0))]
int1 = [(datetime.datetime(2013, 6, 15, 12, 0, 0),
datetime.datetime(2013, 6, 15, 15, 0, 0))]
int2 = [(datetime.datetime(2013, 6, 15, 11, 0, 0),
datetime.datetime(2013, 6, 15, 13, 0, 0)),
(datetime.datetime(2013, 6, 15, 14, 0, 0),
datetime.datetime(2013, 6, 15, 16, 0, 0))]
received = intersect_intervals(int1, int2)
assert_equal(received, expected)