def from_elliptical_cone(cls,
lon,
lat,
a,
b,
pa,
max_depth,
delta_depth=2):
"""
Creates a MOC from an elliptical cone
The ellipse is centered around the (`lon`, `lat`) position. `a` (resp. `b`) corresponds
to the semi-major axis magnitude (resp. semi-minor axis magnitude). `pa` is expressed as a
`~astropy.coordinates.Angle` and defines the position angle of the elliptical cone.
Parameters
----------
lon : `astropy.coordinates.Longitude` or its supertype `astropy.units.Quantity`
The longitude of the center of the elliptical cone.
lat : `astropy.coordinates.Latitude` or its supertype `astropy.units.Quantity`
The latitude of the center of the elliptical cone.
a : `astropy.coordinates.Angle`
The semi-major axis angle of the elliptical cone.
b : `astropy.coordinates.Angle`
The semi-minor axis angle of the elliptical cone.
pa : `astropy.coordinates.Angle`
The position angle (i.e. the angle between the north and the semi-major axis, east-of-north).
max_depth : int
Maximum HEALPix cell resolution.
delta_depth : int, optional
To control the approximation, you can choose to perform the computations at a deeper
depth using the `depth_delta` parameter.
The depth at which the computations will be made will therefore be equal to
`depth` + `depth_delta`.
Returns
-------
result : `~mocpy.moc.MOC`
The resulting MOC
Examples
--------
>>> from mocpy import MOC
>>> import astropy.units as u
>>> from astropy.coordinates import Angle, Longitude, Latitude
>>> moc = MOC.from_elliptical_cone(
... lon=Longitude(0 * u.deg),
... lat=Latitude(0 * u.deg),
... a=Angle(10, u.deg),
... b=Angle(5, u.deg),
... pa=Angle(0, u.deg),
... max_depth=10
... )
"""
lon = lon if isinstance(lon, Longitude) else Longitude(lon)
lat = lat if isinstance(lat, Latitude) else Latitude(lat)
pix, depth, fully_covered_flags = cdshealpix.elliptical_cone_search(
lon, lat, a, b, pa, max_depth, delta_depth, flat=False)
return MOC.from_healpix_cells(pix, depth, fully_covered_flags)
import cdshealpix
from cdshealpix import elliptical_cone_search
import astropy.units as u
from astropy.coordinates import Angle, SkyCoord, Longitude, Latitude
import numpy as np
ipix, depth, fully_covered = elliptical_cone_search(lon=Longitude(0, u.deg),
lat=Latitude(0, u.deg),
a=Angle(50, unit="deg"),
b=Angle(5, unit="deg"),
pa=Angle(30, unit="deg"),
depth=10)
from mocpy import MOC, World2ScreenMPL
moc = MOC.from_healpix_cells(ipix, depth, fully_covered)
# Plot the MOC using matplotlib
import matplotlib.pyplot as plt
fig = plt.figure(111, figsize=(10, 10))
# Define a astropy WCS easily
with World2ScreenMPL(fig,
fov=100 * u.deg,
center=SkyCoord(0, 0, unit="deg", frame="icrs"),
coordsys="icrs",
rotation=Angle(0, u.degree),
projection="AIT") as wcs:
ax = fig.add_subplot(1, 1, 1, projection=wcs)
# Call fill with a matplotlib axe and the `~astropy.wcs.WCS` wcs object.
moc.fill(ax=ax, wcs=wcs, alpha=0.5, fill=True, color="green")
# Draw the perimeter of the MOC in black
import cdshealpix
from cdshealpix import elliptical_cone_search
import astropy.units as u
from astropy.coordinates import Angle, SkyCoord
import numpy as np
ipix, depth, fully_covered = elliptical_cone_search(
lon=0 * u.deg,
lat=0 * u.deg,
a=Angle(50, unit="deg"),
b=Angle(5, unit="deg"),
pa=Angle(30, unit="deg"),
depth=10
)
from mocpy import MOC, WCS
moc = MOC.from_healpix_cells(ipix, depth, fully_covered)
# Plot the MOC using matplotlib
import matplotlib.pyplot as plt
fig = plt.figure(111, figsize=(10, 10))
# Define a astropy WCS easily
with WCS(fig,
fov=100 * u.deg,
center=SkyCoord(0, 0, unit="deg", frame="icrs"),
coordsys="icrs",
rotation=Angle(0, u.degree),
projection="AIT") as wcs:
ax = fig.add_subplot(1, 1, 1, projection=wcs)
# Call fill with a matplotlib axe and the `~astropy.wcs.WCS` wcs object.