Getting Started

General Guidelines

astroplan is based on Astropy and was built around the creation of Python objects that contain all the information needed to perform certain tasks. You, the user, will create and manipulate these objects to plan your observation. For instance, an Target object contains information associated with targets, such as right ascension, declination, etc.

Objects representing celestial bodies like stars (which, if we ignore proper motion, are fixed on the celestial sphere) are created (or “instantiated”) via an FixedTarget object:

from astropy.coordinates import SkyCoord
from astroplan import FixedTarget

coordinates = SkyCoord('19h50m47.6s', '+08d52m12.0s', frame='icrs')
altair = FixedTarget(name='Altair', coord=coordinates)

Alternatively, for objects known to the CDS name resolver, you can quickly retrieve their coordinates with from_name:

altair = FixedTarget.from_name('Altair')

Similarly, an Observer object contains information about the observatory, telescope or place where you are observing, such as longitude, latitude, elevation and other optional parameters. You can initialize an Observer object via the at_site class method:

from astroplan import Observer
observer = Observer.at_site('subaru')

Or you can specify your own location parameters:

import astropy.units as u
from astropy.coordinates import EarthLocation
from pytz import timezone
from astroplan import Observer

longitude = '-155d28m48.900s'
latitude = '+19d49m42.600s'
elevation = 4163 * u.m
location = EarthLocation.from_geodetic(longitude, latitude, elevation)

observer = Observer(name='Subaru Telescope',
               location=location,
               pressure=0.615 * u.bar,
               relative_humidity=0.11,
               temperature=0 * u.deg_C,
               timezone=timezone('US/Hawaii'),
               description="Subaru Telescope on Mauna Kea, Hawaii")

astroplan makes heavy use of certain Astropy machinery, including the coordinates objects and transformations and units. Most importantly for basic use of astroplan is the representation of dates/times as Time objects (note that these are in the UTC timezone by default):

from astropy.time import Time
time = Time(['2015-06-16 06:00:00'])

Since astroplan objects are Python objects, manipulating them or accessing attributes follows Python syntax and conventions. See Python documentation on objects for more information.

Doing More

Now that you know the basics of working with astroplan, check out our Tutorials page for high-level examples of using astroplan, as well as the Reference/API section for more exhaustive documentation and lower-level usage examples.