constraints_example.py

from astroplan import Observer, FixedTarget
from astroplan.constraints import (is_observable, is_always_observable,
                                   AltitudeConstraint, AirmassConstraint,
                                   AtNight)
from astropy.time import Time
import astropy.units as u
import numpy as np

time_range = Time(["2015-01-01", "2015-01-03"])
subaru = Observer.at_site("Subaru")
targets = [FixedTarget.from_name('Polaris'),
           FixedTarget.from_name('Albireo'),
           FixedTarget.from_name('Vega')]

observer = Observer.at_site("Subaru")
constraint_list = [AltitudeConstraint(10*u.deg, 80*u.deg),
                   AirmassConstraint(5), AtNight.twilight_civil()]

# Is target *ever* observable in the time range?
anys = is_observable(constraint_list, time_range, targets, observer)

# Is the target *always* observable in the time range?
alls = is_always_observable(constraint_list, time_range, targets, observer)

# Print results
observability_report = []
justify = 15
def prep_line(*data):
    # For printing data in neat columns
    return ''.join(["{}".format(i).ljust(justify) for i in data])

headers = ['Star', 'ever obs-able', 'always obs-able']
observability_report.append(prep_line(*headers))
observability_report.append(prep_line(*['-'*len(header) for header in headers]))

for target, any, all in zip(targets, anys, alls):
    observability_report.append(prep_line(target.name, any, all))

print "\n".join(observability_report)