In [1]:

    

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

# How to convert: ipython nbconvert --to slides presentation.ipynb --post serve


    

In [21]:

    

# Altitude-azimuth frame: 
from astropy.coordinates import SkyCoord, EarthLocation, AltAz
import astropy.units as u
from astropy.time import Time

# Specify location of Apache Point Observatory with astropy.coordinates.EarthLocation
apache_point = EarthLocation.from_geodetic(-105.82*u.deg, 32.78*u.deg, 2798*u.m)

# Specify star's location with astropy.coordinates.SkyCoord
vega_icrs = SkyCoord(ra=279.235416*u.deg, dec=38.78516*u.deg)

# Initialize an altitude/azimuth frame at the present time
time = Time.now()
altaz_frame = AltAz(obstime=time, location=apache_point)

# Get Vega's alt/az position now
vega_altaz = vega_icrs.transform_to(altaz_frame)
print("Vega (altitude, azimuth) [deg, deg] at {}:\n\t({}, {})"
      .format(time, vega_altaz.alt.degree, vega_altaz.az.degree))


    

    




Vega (altitude, azimuth) [deg, deg] at 2016-02-09 18:00:59.186707:
	(69.4365111185583, 293.9051155643265)

In [3]:

    

# Where is the sun right now?
from astropy.coordinates import get_sun

sun = get_sun(time)
print(sun)


    

    




<SkyCoord (GCRS: obstime=2016-02-09 18:00:45.558567, obsgeoloc=[ 0.  0.  0.] m, obsgeovel=[ 0.  0.  0.] m / s): (ra, dec, distance) in (deg, deg, AU)
    (323.58130405, -14.43302781, 0.986627)>

In [4]:

    

from astroplan import Observer

# Construct an astroplan.Observer at Apache Point Observatory
apache_point = Observer.at_site("Apache Point")
apache_point = Observer.at_site("APO")   # also works

print(apache_point.location.to_geodetic())


    

    




(<Longitude -105.82000000000002 deg>, <Latitude 32.78000000000001 deg>, <Quantity 2797.9999999996007 m>)

In [5]:

    

from astroplan import FixedTarget

# Construct an astroplan.FixedTarget for Vega
vega = FixedTarget.from_name("Vega")  # (with internet access)

# # (without internet access)
# vega_icrs = SkyCoord(ra=279.235416*u.deg, dec=38.78516*u.deg)
# vega = FixedTarget(coord=vega_icrs, name="Vega")

vega_altaz = apache_point.altaz(time, vega)

print("Vega (altitude, azimuth) [deg, deg] at {}:\n\t({}, {})"
      .format(time, vega_altaz.alt.degree, vega_altaz.az.degree))


    

    




Vega (altitude, azimuth) [deg, deg] at 2016-02-09 18:00:45.558567:
	(69.47999708651103, 293.92168741017167)

In [6]:

    

apache_point.is_night(time)


    

    
Out[6]:





False

In [7]:

    

apache_point.target_is_up(time, vega)


    

    
Out[7]:





True

In [8]:

    

# Local Sidereal time
apache_point.local_sidereal_time(time)


    

    
Out[8]:





$20^\mathrm{h}14^\mathrm{m}33.7867^\mathrm{s}$

In [9]:

    

# Hour angle
apache_point.target_hour_angle(time, vega)


    

    
Out[9]:





$1^\mathrm{h}37^\mathrm{m}37.4503^\mathrm{s}$

In [10]:

    

# Parallactic angle
apache_point.parallactic_angle(time, vega)


    

    
Out[10]:





$-1.40668\mathrm{rad}$

In [11]:

    

sunset = apache_point.sun_set_time(time, which='next')

print("{0.jd} = {0.iso}".format(sunset))


    

    




2457428.5303427037 = 2016-02-10 00:43:41.610

In [12]:

    

vega_rise = apache_point.target_rise_time(time, vega, which='next')

print(vega_rise.iso)


    

    




2016-02-10 08:16:34.025

In [13]:

    

astronomical_twilight = apache_point.twilight_evening_astronomical(time, which='next')

print(astronomical_twilight.iso)


    

    




2016-02-10 02:11:13.449

In [28]:

    

# Specify your time zone with `pytz`
import pytz

my_timezone = pytz.timezone('US/Pacific')

astronomical_twilight.to_datetime(my_timezone)


    

    
Out[28]:





datetime.datetime(2016, 2, 9, 18, 11, 13, 449428, tzinfo=<DstTzInfo 'US/Pacific' PST-1 day, 16:00:00 STD>)

In [14]:

    

%%writefile targets.txt
# name ra_degrees dec_degrees
Polaris 37.95456067 89.26410897
Vega 279.234734787 38.783688956
Albireo 292.68033548 27.959680072
Algol 47.042218553 40.955646675
Rigel 78.634467067 -8.201638365
Regulus 152.092962438 11.967208776


    

    




Overwriting targets.txt

In [15]:

    

# Read in the table of targets
from astropy.table import Table

target_table = Table.read('targets.txt', format='ascii')

# Create astroplan.FixedTarget objects for each one in the table
from astropy.coordinates import SkyCoord
import astropy.units as u

from astroplan import FixedTarget

targets = [FixedTarget(coord=SkyCoord(ra=ra*u.deg, dec=dec*u.deg), name=name)
           for name, ra, dec in target_table]


    

In [16]:

    

from astroplan import Observer
from astropy.time import Time

subaru = Observer.at_site("Subaru")
time_range = Time(["2015-08-01 06:00", "2015-08-01 12:00"])


    

In [17]:

    

from astroplan import (AltitudeConstraint, AirmassConstraint,
                       AtNightConstraint)

# Define constraints:
constraints = [AltitudeConstraint(10*u.deg, 80*u.deg),
               AirmassConstraint(5), AtNightConstraint.twilight_civil()]


    

In [18]:

    

from astroplan import is_observable, is_always_observable

# Compute: are targets *ever* observable in the time range?
ever_observable = is_observable(constraints, subaru, targets, time_range=time_range)

# Compute: are targets *always* observable in the time range?
always_observable = is_always_observable(constraints, subaru, targets, time_range=time_range)


    

In [19]:

    

from astroplan import observability_table

table = observability_table(constraints, subaru, targets, time_range=time_range)

print(table)


    

    




target name ever observable always observable fraction of time observable
----------- --------------- ----------------- ---------------------------
    Polaris            True              True                         1.0
       Vega            True              True                         1.0
    Albireo            True             False              0.833333333333
      Algol            True             False              0.166666666667
      Rigel           False             False                         0.0
    Regulus           False             False                         0.0

In [20]:

    

%matplotlib inline
from astroplan.plots import plot_sky, plot_airmass

import numpy as np
import matplotlib.pyplot as plt

plot_times = time_range[0] + np.linspace(0, 1, 10)*(time_range[1] - time_range[0])

fig = plt.figure(figsize=(12, 6))
ax0 = fig.add_subplot(121, projection='polar')
ax1 = fig.add_subplot(122)

# Plot Vega track
plot_sky(targets[1], subaru, plot_times, ax=ax0,
         style_kwargs=dict(color='b', label='Vega'))
plot_airmass(targets[1], subaru, plot_times, ax=ax1,
             style_kwargs=dict(color='b'))

# Plot Albireo track
plot_sky(targets[2], subaru, plot_times,  ax=ax0,
         style_kwargs=dict(color='r', label='Albireo'))
plot_airmass(targets[2], subaru, plot_times, ax=ax1,
             style_kwargs=dict(color='r'))

fig.subplots_adjust(wspace=0.4);


    

In [26]:

    

# This method requires astroquery, wcsaxes
from astroplan.plots import plot_finder_image

m1 = FixedTarget.from_name('M1')

plot_finder_image(m1, survey='DSS');