def test_load(self):
"""Test loading a filter."""
# load it via Filter
f = Filter('V', path=data_filename('filters'))
# load it as Spectrum
s = Spectrum.load(data_filename('filters/V.txt'))
# should be identical
assert np.array_equal(f.wave, s.wave)
assert np.array_equal(f.throughput, s.flux)
def test_squared(self):
# filename for spectrum
filename = data_filename('spectra/ngc6397id000010554jd2456865p5826f000.fits')
# load spectrum and sigma
spec = Spectrum.load(filename)
sigma = fits.getdata(filename, 'SIGMA')
# create weight
weight = WeightFromSigma(squared=True)
# compare
diff = weight(spec, filename) - 1./sigma**2
assert np.max(np.abs(diff)) < 1e-5
def test_default(self):
# filename for spectrum
filename = data_filename(
'spectra/ngc6397id000010554jd2456865p5826f000.fits')
# load spectrum and sigma
spec = Spectrum.load(filename)
# create weight
weight = WeightRanges(ranges=[(4841., 4881., 10.)], initial=1.)
w = weight(spec, filename)
# first pixel should be one
assert w[0] == 1.
# get pixel at 4861AA and test it
i = spec.index_of_wave(4861)
assert w[i] == 10.
def test_apply(self):
"""Test applying a filter."""
# load it via Filter
f = Filter('V', path=data_filename('filters'))
# load spectrum, fix flux (which is given in 1e20erg/s/cm/cm2) and resample filter
s = Spectrum.load(
data_filename('spectra/ngc6397id000010554jd2456865p5826f000.fits'))
s /= 1e20
f.resample(spec=s, inplace=True)
# calculate V mag as ST and VEGAMAG
st = f.stmag(s)
vega = f.vegamag(s)
# F606W mag is 13.17, V mag should be close to 13.4
assert abs(st - 13.4) < 0.1
assert abs(vega - 13.4) < 0.1
def test_resample(self):
"""Test resampling a filter."""
# load it via Filter
f = Filter('V', path=data_filename('filters'))
# integrate it
int1 = np.trapz(f.throughput, f.wave)
# load spectrum and resample filter
s = Spectrum.load(
data_filename('spectra/ngc6397id000010554jd2456865p5826f000.fits'))
f.resample(spec=s, inplace=True)
# integrate it again
int2 = np.trapz(f.throughput, f.wave)
# integral should not have changed significantly
assert abs(int1 - int2) < 1