Source code for skysurvey.target.stars
"""
This module defines StableTarget and Star, representing time-independent point sources such as stars.
"""
import numpy as np
from .core import Target
[docs]
class StableTarget( Target ):
"""
A class to model targets with fixed, time-independent properties.
Parameters
----------
_KIND : str
The transient type. Default is ``"stable"``.
_MODEL : dict
The model to use. The default is a dictionary with the following
keys:
- `radec`: The ra and dec of the target.
- `magobs`: Randomly drawn observed magnitudes of the target, using :meth:`random_magobs`.
"""
_KIND = "stable"
_MODEL = dict( radec = {"func":"random",
"kwargs":dict(ra_range=[0, 360], dec_range=[-30, 90]),
"as":["ra","dec"]},
magobs = {"func": "random_magobs",
"kwargs": dict(zpmax=22.5)},
)
[docs]
@staticmethod
def random_magobs(size=None, zpmax=22.5, scale=3, rng=None):
"""Draw random observed magnitudes from an exponential decay distribution.
Parameters
----------
size : int, optional
Number of magnitudes to draw. Default is None.
zpmax : float, optional
Upper magnitude limit. Default is 22.5.
scale : float, optional
Scale parameter of the exponential distribution. Default is 3.
rng : None, int, or (Bit)Generator, optional
Seed for the random number generator. Default is None.
Returns
-------
array
Randomly drawn observed magnitudes.
"""
rng = np.random.default_rng(rng)
exp_decay = rng.exponential(scale=scale, size=size)
return zpmax-exp_decay
[docs]
class Star( StableTarget ):
"""
A class to model stars, modelled as a stable point source.
Parameters
----------
_KIND : str
The transient type. Default is ``"star"``.
"""
_KIND = "star"
