def _comets(self) -> DataFrame:
with self.load.open(mpc.COMET_URL) as f:
return (
mpc.load_comets_dataframe(f).sort_values("reference").groupby(
"designation",
as_index=False).last().set_index("designation",
drop=False))
def main():
f = load.open(mpc.COMET_URL)
t0 = time()
c = mpc.load_comets_dataframe(f)
print(time() - t0, 'seconds for load_comets_dataframe()')
assert len(c) == 864
f.seek(0)
t0 = time()
c = mpc.load_comets_dataframe_slow(f)
print(time() - t0, 'seconds for load_comets_dataframe_slow()')
assert len(c) == 864
def get_comet(name, timestamp):
# https://rhodesmill.org/skyfield/example-plots.html#drawing-a-finder-chart-for-comet-neowise
# https://astroquery.readthedocs.io/en/latest/mpc/mpc.html
# name = "C/2020 F3 (NEOWISE)"
# https://www.minorplanetcenter.net/iau/info/CometOrbitFormat.html
with load.open(mpc.COMET_URL) as f:
comets = mpc.load_comets_dataframe(f)
comets = (comets.sort_values('reference')
.groupby('designation', as_index=False).last()
.set_index('designation', drop=False))
row = comets.loc[name]
print(row)
ts = load.timescale()
eph = load('de421.bsp')
sun, earth = eph['sun'], eph['earth']
comet = sun + mpc.comet_orbit(row, ts, GM_SUN)
t = ts.utc(timestamp.year, timestamp.month, timestamp.day, timestamp.hour, timestamp.minute)
ra, dec, distance = earth.at(t).observe(comet).radec()
result = {}
result['name'] = name
result['designation'] = row['designation']
result['timestamp'] = str(timestamp)
result['ra'] = str(ra)
result['dec'] = str(dec)
result['ra_decimal'] = str(ra.hours * 15)
result['dec_decimal'] = str(dec.degrees)
result['distance'] = str(distance)
result['magnitude_g'] = row['magnitude_g']
result['magnitude_k'] = row['magnitude_k']
result['visual_magnitude'] = row['magnitude_k']
result['row'] = row
return result,comet
def test_comet_with_eccentricity_of_exactly_one():
ts = load.timescale()
t = ts.utc(2020, 8, 13)
planets = load('de421.bsp')
earth, sun = planets['earth'], planets['sun']
data = (b' CK15A020 2015 08 1.8353 5.341055 1.000000 208.8369 '
b'258.5042 109.1696 10.5 4.0 C/2015 A2 (PANSTARRS)'
b' MPC 93587')
with BytesIO(data) as f:
df = mpc.load_comets_dataframe(f)
df = df[df['designation'] == 'C/2015 A2 (PANSTARRS)']
comet = mpc.comet_orbit(df.iloc[0], ts, GM_SUN)
ra, dec, distance = earth.at(t).observe(sun + comet).radec()
# These are exactly the RA and declination from the Minor Planet
# Center for this comet! (The RA seconds returned by Skyfield
# actually say "46.45s", which would round up to 46.5, but what's a
# tenth of an arcsecond among friends?)
assert str(ra).startswith('18h 46m 46.4')
assert str(dec).startswith("-72deg 05' 33.")
# time `t` we use for everything else.
ts = load.timescale()
t_comet = ts.utc(2020, 7, range(17, 27))
t = t_comet[len(t_comet) // 2] # middle date
# An ephemeris from the JPL provides Sun and Earth positions.
eph = load('de421.bsp')
sun = eph['sun']
earth = eph['earth']
# The Minor Planet Center data file provides the comet orbit.
with load.open(mpc.COMET_URL) as f:
comets = mpc.load_comets_dataframe(f)
comets = comets.set_index('designation', drop=False)
row = comets.loc['C/2020 F3 (NEOWISE)']
comet = sun + mpc.comet_orbit(row, ts, GM_SUN)
# The Hipparcos mission provides our star catalog.
with load.open(hipparcos.URL) as f:
stars = hipparcos.load_dataframe(f)
# And the constellation outlines come from Stellarium. We make a list
# of the stars at which each edge stars, and the star at which each edge
# ends.
url = ('https://raw.githubusercontent.com/Stellarium/stellarium/master'
def create_starmap(command, observation_id):
# The comet is plotted on several dates `t_comet`. But the stars only
# need to be drawn once, so we take the middle comet date as the single
# time `t` we use for everything else.
ts = load.timescale()
t_comet = ts.utc(2020, 8, range(1, 10))
t = t_comet[len(t_comet) // 2] # middle date
# An ephemeris from the JPL provides Sun and Earth positions.
eph = load('de421.bsp')
sun = eph['sun']
earth = eph['earth']
# The Minor Planet Center data file provides the comet orbit.
with load.open(mpc.COMET_URL) as f:
comets = mpc.load_comets_dataframe(f)
comets = (comets.sort_values('reference')
.groupby('designation', as_index=False).last()
.set_index('designation', drop=False))
row = comets.loc['C/2020 F3 (NEOWISE)']
comet = sun + mpc.comet_orbit(row, ts, GM_SUN)
# The Hipparcos mission provides our star catalog.
# with load.open(hipparcos.URL) as f:
with load.open(settings.MY_HIPPARCOS_URL) as f:
stars = hipparcos.load_dataframe(f)
# And the constellation outlines come from Stellarium. We make a list
# of the stars at which each edge stars, and the star at which each edge
# ends.
url = ('https://raw.githubusercontent.com/Stellarium/stellarium/master'
'/skycultures/western_SnT/constellationship.fab')
with load.open(url) as f:
constellations = stellarium.parse_constellations(f)
edges = [edge for name, edges in constellations for edge in edges]
edges_star1 = [star1 for star1, star2 in edges]
edges_star2 = [star2 for star1, star2 in edges]
# We will center the chart on the comet's middle position.
center = earth.at(t).observe(comet)
projection = build_stereographic_projection(center)
field_of_view_degrees = 30.0
limiting_magnitude = 8.0
# Now that we have constructed our projection, compute the x and y
# coordinates that each star and the comet will have on the plot.
star_positions = earth.at(t).observe(Star.from_dataframe(stars))
stars['x'], stars['y'] = projection(star_positions)
comet_x, comet_y = projection(earth.at(t_comet).observe(comet))
# Create a True/False mask marking the stars bright enough to be
# included in our plot. And go ahead and compute how large their
# markers will be on the plot.
bright_stars = (stars.magnitude <= limiting_magnitude)
magnitude = stars['magnitude'][bright_stars]
marker_size = (0.5 + limiting_magnitude - magnitude) ** 2.0
# The constellation lines will each begin at the x,y of one star and end
# at the x,y of another. We have to "rollaxis" the resulting coordinate
# array into the shape that matplotlib expects.
xy1 = stars[['x', 'y']].loc[edges_star1].values
xy2 = stars[['x', 'y']].loc[edges_star2].values
lines_xy = np.rollaxis(np.array([xy1, xy2]), 1)
# Time to build the figure!
fig, ax = plt.subplots(figsize=[9, 9])
# Draw the constellation lines.
ax.add_collection(LineCollection(lines_xy, colors='#00f2'))
# Draw the stars.
ax.scatter(stars['x'][bright_stars], stars['y'][bright_stars],
s=marker_size, color='k')
# Draw the comet positions, and label them with dates.
comet_color = '#f00'
offset = 0.002
ax.plot(comet_x, comet_y, '+', c=comet_color, zorder=3)
for xi, yi, tstr in zip(comet_x, comet_y, t_comet.utc_strftime('%m/%d')):
tstr = tstr.lstrip('0')
text = ax.text(xi + offset, yi - offset, tstr, color=comet_color,
ha='left', va='top', fontsize=9, weight='bold', zorder=-1)
text.set_alpha(0.5)
# Finally, title the plot and set some final parameters.
angle = np.pi - field_of_view_degrees / 360.0 * np.pi
limit = np.sin(angle) / (1.0 - np.cos(angle))
ax.set_xlim(-limit, limit)
ax.set_ylim(-limit, limit)
ax.xaxis.set_visible(False)
ax.yaxis.set_visible(False)
ax.set_aspect(1.0)
ax.set_title('Comet NEOWISE {} through {}'.format(
t_comet[0].utc_strftime('%Y %B %d'),
t_comet[-1].utc_strftime('%Y %B %d'),
))
# Save.
filename = 'starmap.png'
path = os.path.join(settings.MEDIA_ROOT, filename)
fig.savefig(path, bbox_inches='tight')
image_url = os.path.join(settings.MEDIA_URL, filename)
return image_url
