def __init__(self, filename):
"""
Load PSF parameters from a file
Loads x, y, wavelength information for spectral traces and fills:
self.npix_x #- number of columns in the target image
self.npix_y #- number of rows in the target image
self.nspec #- number of spectra (fibers)
self.nwave #- number of wavelength samples per spectrum
Subclasses of this class define the xypix(ispec, wavelength) method
to access the projection of this PSF into pixels.
"""
#- Load basic dimensions
hdr = fits.getheader(filename)
self.npix_x = hdr['NPIX_X']
self.npix_y = hdr['NPIX_Y']
self.nspec = hdr['NSPEC']
#- PSF model error
if 'PSFERR' in hdr:
self.psferr = hdr['PSFERR']
else:
self.psferr = 0.01
#- Load x, y legendre coefficient tracesets
with fits.open(filename) as fx:
xc = fx['XCOEFF'].data
hdr = fx['XCOEFF'].header
self._x = TraceSet(xc, domain=(hdr['WAVEMIN'], hdr['WAVEMAX']))
yc = fx['YCOEFF'].data
hdr = fx['YCOEFF'].header
self._y = TraceSet(yc, domain=(hdr['WAVEMIN'], hdr['WAVEMAX']))
#- Create inverse y -> wavelength mapping
self._w = self._y.invert()
#- Cache min/max wavelength per fiber at pixel edges
self._wmin_spec = self.wavelength(None, -0.5)
self._wmax_spec = self.wavelength(None, self.npix_y - 0.5)
self._wmin = np.min(self._wmin_spec)
self._wmin_all = np.max(self._wmin_spec)
self._wmax = np.max(self._wmax_spec)
self._wmax_all = np.min(self._wmax_spec)
#- Filled only if needed
self._xsigma = None
self._ysigma = None
def __init__(self, filename):
"""
Initialize GaussHermitePSF from input file
"""
#- Check that this file is a current generation Gauss Hermite PSF
fx = fits.open(filename, memmap=False)
self._polyparams = hdr = fx[1].header
if 'PSFTYPE' not in hdr:
raise ValueError('Missing PSFTYPE keyword')
if hdr['PSFTYPE'] != 'GAUSS-HERMITE2':
raise ValueError('PSFTYPE {} is not GAUSS-HERMITE'.format(hdr['PSFTYPE']))
if 'PSFVER' not in hdr:
raise ValueError("PSFVER missing; this version not supported")
if hdr['PSFVER'] < '1':
raise ValueError("Only GAUSS-HERMITE versions 1.0 and greater are supported")
#- Calculate number of spectra from FIBERMIN and FIBERMAX (inclusive)
self.nspec = hdr['FIBERMAX'] - hdr['FIBERMIN'] + 1
#- Other necessary keywords
self.npix_x = hdr['NPIX_X']
self.npix_y = hdr['NPIX_Y']
#- PSF model error
if 'PSFERR' in hdr:
self.psferr = hdr['PSFERR']
else:
self.psferr = 0.01
#- Load the parameters into self.coeff dictionary keyed by PARAM
#- with values as TraceSets for evaluating the Legendre coefficients
data = fx[1].data
self.coeff = dict()
for p in data:
domain = (p['WAVEMIN'], p['WAVEMAX'])
for p in data:
name = p['PARAM'].strip()
self.coeff[name] = TraceSet(p['COEFF'], domain=domain)
#- Pull out x and y as special tracesets
self._x = self.coeff['X']
self._y = self.coeff['Y']
#- Create inverse y -> wavelength mapping
self._w = self._y.invert()
#- Cache min/max wavelength per fiber at pixel edges
self._wmin_spec = self.wavelength(None, -0.5)
self._wmax_spec = self.wavelength(None, self.npix_y-0.5)
self._wmin = np.min(self._wmin_spec)
self._wmin_all = np.max(self._wmin_spec)
self._wmax = np.max(self._wmax_spec)
self._wmax_all = np.min(self._wmax_spec)
#- Filled only if needed
self._xsigma = None
self._ysigma = None
#- Cache hermitenorm polynomials so we don't have to create them
#- every time xypix is called
self._hermitenorm = list()
maxdeg = max(hdr['GHDEGX'], hdr['GHDEGY'], hdr['GHDEGX2'], hdr['GHDEGY2'])
for i in range(maxdeg+1):
self._hermitenorm.append( sp.hermitenorm(i) )
fx.close()
