66 lines
2.4 KiB
Python
66 lines
2.4 KiB
Python
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from .AGriddedPSF import AGriddedPSF
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from ...lib.logger import logger
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import numpy as np
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import astropy.units as u
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from astropy.io import fits
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class FITS(AGriddedPSF):
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"""
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A class for modelling the PSF from a FITS-file
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"""
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@u.quantity_input(wl="length", d_aperture="length", pixel_size="length")
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def __init__(self, file: str, f_number: float, wl: u.Quantity, d_aperture: u.Quantity, osf: float,
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pixel_size: u.Quantity):
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"""
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Initialize a new PSF from a FITS-file.
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Parameters
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----------
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file : str
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Path to the FITS-file. The origin of the coordinate system is in the upper left corner of the matrix
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f_number : float
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The working focal number of the optical system
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wl : Quantity
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The central wavelength which is used for calculating the PSF
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d_aperture : Quantity
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The diameter of the telescope's aperture.
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osf : float
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The oversampling factor to be used for oversampling the PSF with regards to the pixel size.
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pixel_size : Quantity
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The size of a pixel as length-quantity.
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"""
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# Open the fits file
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hdul = fits.open(file)
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# Check if a dataset is available
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if len(hdul) < 1:
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logger.error("PSF FITS file must contain a PSF dataset")
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# Extract PSF
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psf = hdul[0].data
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# Extract PSF grid size
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if "XPIXSZ" in hdul[0].header:
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if "YPIXSZ" in hdul[0].header:
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grid_delta = np.array([hdul[0].header["XPIXSZ"], hdul[0].header["YPIXSZ"]]) << u.um
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else:
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grid_delta = np.array([hdul[0].header["XPIXSZ"], hdul[0].header["XPIXSZ"]]) << u.um
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elif "PSFSCALE" in hdul[0].header:
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grid_delta = (2 * f_number * d_aperture * np.tan(hdul[0].header["PSFSCALE"] / 2 * u.arcsec)).to(u.um)
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grid_delta = u.Quantity([grid_delta, grid_delta])
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else:
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grid_delta = u.Quantity([pixel_size, pixel_size])
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# Extract PSF center point
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if "XPSFCTR" in hdul[0].header and "YPSFCTR" in hdul[0].header:
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center_point = [hdul[0].header["XPSFCTR"], hdul[0].header["YPSFCTR"]]
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else:
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center_point = [x / 2 for x in list(self._psf.shape)]
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# Close the file
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hdul.close()
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super().__init__(psf, f_number, wl, d_aperture, osf, pixel_size, grid_delta, center_point)
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