transitingtonight.py

"""
Recipe for calculating which bright exoplanets will be transiting tonight and 
visible from Apache Point Obsevatory. 
"""

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)
from astropy.time import Time
from astroplan import Observer, get_site, Exoplanets

# Get an instance of the exoplanet database
db = Exoplanets()
planets = db.get_available_planets()

# Filter for only the bright planets (found in ground based, wide field surveys)
bright_planets = [planet for planet in planets if 'HAT' in planet or
                  'WASP' in planet or 'HD' in planet or 'TrES' in planet]

# Initialize an observer at APO
apo = Observer(location=get_site('APO'))
present_time = Time.now()

# Figure out when "tonight" is
if not apo.is_night(present_time):
    # If it's currently day time at runtime
    tonight_start = apo.sun_set_time(present_time, which='next')
    tonight_end = apo.sun_rise_time(present_time, which='next')
else:
    tonight_start = present_time
    tonight_end = apo.sun_rise_time(present_time, which='next')

# Identify visible transits of planets with bright hosts, print them
for planet in bright_planets:
    visible_transits = db.get_visible_transits(apo, planet, tonight_start,
                                               tonight_end)
    if visible_transits is not None:
        print("Planet: {planet}\t Time: {time.iso}".format(planet=planet,
                                                           time=visible_transits))