from ..target.ATarget import ATarget from ..SpectralQty import SpectralQty import astropy.units as u from astropy.modeling.models import BlackBody from ...lib.helpers import error from ..Entry import Entry from typing import Union class BlackBodyTarget(ATarget): """ This class models the spectral flux density of a star of given magnitude using as black body radiator """ # Bands from Handbook of Space Astronomy and Astrophysics p. 139 _band = dict(U=dict(wl=365 * u.nm, sfd=4.27e-11 * u.W / (u.m ** 2 * u.nm)), B=dict(wl=440 * u.nm, sfd=6.61e-11 * u.W / (u.m ** 2 * u.nm)), V=dict(wl=550 * u.nm, sfd=3.64e-11 * u.W / (u.m ** 2 * u.nm)), R=dict(wl=700 * u.nm, sfd=1.74e-11 * u.W / (u.m ** 2 * u.nm)), I=dict(wl=900 * u.nm, sfd=8.32e-12 * u.W / (u.m ** 2 * u.nm)), J=dict(wl=1250 * u.nm, sfd=3.18e-12 * u.W / (u.m ** 2 * u.nm)), H=dict(wl=1650 * u.nm, sfd=1.18e-12 * u.W / (u.m ** 2 * u.nm)), K=dict(wl=2200 * u.nm, sfd=4.17e-13 * u.W / (u.m ** 2 * u.nm)), L=dict(wl=3600 * u.nm, sfd=4.17e-13 * u.W / (u.m ** 2 * u.nm)), M=dict(wl=4800 * u.nm, sfd=4.17e-13 * u.W / (u.m ** 2 * u.nm)), N=dict(wl=10200 * u.nm, sfd=4.17e-13 * u.W / (u.m ** 2 * u.nm))) @u.quantity_input(wl_bins='length', temp=[u.Kelvin, u.Celsius], mag=u.mag) def __init__(self, wl_bins: u.Quantity, temp: u.Quantity = 5778 * u.K, mag: u.Quantity = 0 * u.mag, band: str = "V", size: str = "Point"): """ Initialize a new black body point source Parameters ---------- wl_bins : length-Quantity Wavelengths used for binning temp : Quantity in Kelvin / Celsius Temperature of the black body mag : Quantity in mag Desired apparent magnitude of the point source band : str Band used for fitting the planck curve to a star of 0th magnitude. Can be one of [U, B, V, R, I, J, H, K]. size : str The size of the target. Can be either point or extended Returns ------- """ if band.upper() not in self._band.keys(): error("Band has to be one of '[" + ", ".join(list(self._band.keys())) + "]'") # Create blackbody model with given temperature bb = BlackBody(temperature=temp, scale=1 * u.W / (u.m ** 2 * u.nm * u.sr)) # Calculate the correction factor for a star of 0th magnitude using the spectral flux density # for the central wavelength of the given band factor = self._band[band.upper()]["sfd"] / (bb(self._band[band.upper()]["wl"]) * u.sr) * u.sr # Calculate spectral flux density for the given wavelengths and scale it for a star of the given magnitude sfd = bb(wl_bins) * factor * 10 ** (- 2 / 5 * mag / u.mag) # Initialize super class super().__init__(SpectralQty(wl_bins, sfd), wl_bins, size) @staticmethod def check_config(conf: Entry) -> Union[None, str]: """ Check the configuration for this class Parameters ---------- conf : Entry The configuration entry to be checked. Returns ------- mes : Union[None, str] The error message of the check. This will be None if the check was successful. """ mes = conf.check_quantity("temp", u.K) if mes is not None: return mes mes = conf.check_quantity("mag", u.mag) if mes is not None: return mes mes = conf.check_selection("band", ["U", "B", "V", "R", "I", "J", "H", "K", "L", "M", "N"]) if mes is not None: return mes mes = conf.check_selection("size", ["point", "extended"]) if mes is not None: return mes