from typing import Literal
import astropy.units as u # type: ignore[import-untyped]
import numpy as np
import numpy.typing as npt
from astropy.coordinates import SkyCoord # type: ignore[import-untyped]
from astropy.time import Time # type: ignore[import-untyped]
from pydantic import Field
from ...core.enums import ConstraintType
from ...ephemeris import Ephemeris
from .base import ConstraintABC, get_slice
[docs]
class SunAngleConstraint(ConstraintABC):
"""
For a given Sun avoidance angle, is a given coordinate inside this
constraint?
Parameters
----------
min_angle
The minimum angle from the Sun that the spacecraft can point.
max_angle
The maximum angle from the Sun that the spacecraft can point.
Methods
-------
__call__(coord, ephemeris, sun_radius_angle=None)
Checks if a given coordinate is inside the constraint.
"""
[docs]
name: Literal[ConstraintType.SUN] = ConstraintType.SUN
[docs]
short_name: Literal["Sun"] = "Sun"
[docs]
min_angle: float | None = Field(default=None, ge=0, le=180, description="Minimum angle from the Sun")
[docs]
max_angle: float | None = Field(default=None, ge=0, le=180, description="Maximum angle from the Sun")
[docs]
def __call__(self, time: Time, ephemeris: Ephemeris, coordinate: SkyCoord) -> npt.NDArray[np.bool_]:
"""
Check for a given time, ephemeris and coordinate if positions given are
inside the Sun constraint. This is done by checking if the
separation between the Sun and the spacecraft is less than the
a given minimum angle or greater than a maximum angle (essentially an
anti-Sun constraint).
Parameters
----------
coordinate : SkyCoord
The coordinate to check.
time : Time
The time to check.
ephemeris : Ephemeris
The ephemeris object.
Returns
-------
bool
`True` if the coordinate is inside the constraint, `False`
otherwise.
"""
# Find a slice what the part of the ephemeris that we're using
i = get_slice(time, ephemeris)
# Calculate the angular distance between the center of the Sun and
# the object. Note that creating the SkyCoord here from ra/dec stored
# in the ephemeris `sun` is 3x faster than just doing the separation
# directly with `sun`.
assert ephemeris.sun is not None
# Construct the constraint based on the minimum and maximum angles
in_constraint = np.zeros(len(ephemeris.sun[i]), dtype=bool)
self.computed_values.sun_angle = SkyCoord(ephemeris.sun[i].ra, ephemeris.sun[i].dec).separation(
coordinate
)
if self.min_angle is not None:
in_constraint |= self.computed_values.sun_angle < self.min_angle * u.deg
if self.max_angle is not None:
in_constraint |= self.computed_values.sun_angle > self.max_angle * u.deg
# Return the result as True or False, or an array of True/False
return in_constraint