def black_body_spectrum(cls,
temperature=9500,
amplitude=0,
filter_curve=None,
waves=None):
"""
Produce a blackbody spectrum for a given temperature and scale it to a magnitude
in a filter
Parameters
----------
temperature: the temperature in Kelvin degrees
amplitude: `astropy.Quantity``, float
The value that the spectrum should have in the given filter. Acceptable
astropy quantities are:
- u.mag : Vega magnitudes
- u.ABmag : AB magnitudes
- u.STmag : HST magnitudes
- u.Jy : Jansky per filter bandpass
Additionally the ``FLAM`` and ``FNU`` units from ``synphot.units`` can
be used when passing the quantity for ``amplitude``:
filter_curve : str
Name of a filter from
- a generic filter name (see ``FILTER_DEFAULTS``)
- a spanish-vo filter service reference (e.g. ``"Paranal/HAWKI.Ks"``)
- a filter in the spextra database
- a filename with the filter file
- a ``Passband`` or ``synphot.SpectralElement`` object
Returns
-------
a scaled black-body spectrum
"""
if waves is None: # set a default waveset with R~805
waves, info = utils.generate_wavelengths(minwave=100,
maxwave=50000,
num=5000,
log=True,
wave_unit=u.AA)
if isinstance(amplitude, u.Quantity) is False:
amplitude = amplitude * u.ABmag
bb = BlackBody1D(temperature=temperature)
sp = cls(modelclass=Empirical1D, points=waves, lookup_table=bb(waves))
sp = sp.scale_to_magnitude(amplitude=amplitude,
filter_curve=filter_curve)
sp.repr = "Spextrum.black_body_spectrum(amplitude=%s, temperature=%s, filter_curve=%s)" % \
(str(amplitude), str(temperature), str(filter_curve))
return sp
def powerlaw(cls,
alpha=1,
x_0=5000,
amplitude=0,
filter_curve=None,
waves=None):
"""
Return a power law spectrum F(lambda) ~ lambda^alpha scaled to a magnitude
(amplitude) in an particular band
Parameters
----------
alpha : The spectral slope
x_0 : float, u.Quantity
Pivot wavelength
amplitude : float, u.Quantity
normalize the spectrum to that quantity
filter_curve : str
Name of a filter from
- a generic filter name (see ``FILTER_DEFAULTS``)
- a spanish-vo filter service reference (e.g. ``"Paranal/HAWKI.Ks"``)
- a filter in the spextra database
- a filename with the filter file
- a ``Passband`` or ``synphot.SpectralElement`` object
Returns
-------
"""
if waves is None: # set a default waveset with R~805
waves, info = utils.generate_wavelengths(minwave=100,
maxwave=50000,
num=5000,
log=True,
wave_unit=u.AA)
if isinstance(amplitude, u.Quantity) is False:
amplitude = amplitude * u.ABmag
pl = PowerLawFlux1D(amplitude,
alpha=alpha,
x_0=x_0,
amplitude=amplitude)
sp = cls(modelclass=Empirical1D, points=waves, lookup_table=pl(waves))
sp = sp.scale_to_magnitude(amplitude=amplitude,
filter_curve=filter_curve)
sp.repr = "Spextrum.powerlaw(alpha=%s, x_0=%s, amplitude=%s, filter_curve=%s)" % \
(str(alpha), str(x_0), str(amplitude), str(filter_curve))
return sp
class Conf(ConfigNamespace):
"""Configuration parameters."""
# Set up default wavelength
_wave, _wave_str = generate_wavelengths(minwave=500,
maxwave=26000,
num=10000,
delta=None,
log=True,
wave_unit='angstrom')
# Root directory
rootdir = ConfigItem(os.environ.get('PYSYN_CDBS', '/grp/redcat/trds'),
'TRDS data root directory')
# Graph, optical component, and thermal component tables
graphtable = ConfigItem('mtab$*_tmg.fits', 'Graph table')
comptable = ConfigItem('mtab$*_tmc.fits', 'Component table')
thermtable = ConfigItem('mtab$*_tmt.fits', 'Thermal table')
# Default wavelength in Angstrom and its description
waveset_array = ConfigItem(_wave.value.tolist(),
'Default wavelength set in Angstrom',
'float_list')
waveset = ConfigItem(_wave_str, 'Default wavelength set description')
# Telescope primary mirror collecting area in cm^2
area = ConfigItem(45238.93416, 'Telescope collecting area in cm^2')
# Common filter name
clear_filter = ConfigItem('clear', 'Name for a clear filter')
# Wavelength catalog file
wavecatfile = ConfigItem('synphot$wavecats/wavecat.dat',
'Wavelength catalog file')
# Detector parameters file
detectorfile = ConfigItem('synphot$detectors.dat',
'Detector parameters file')
# IRAF shortcuts file for stsynphot.stio.irafconvert()
irafshortcutfile = ConfigItem(
'synphot$irafshortcuts.txt',
'col1=shortcut_name col2=relpath_to_rootdir, has header.')
# Clean up
del _wave
del _wave_str
def test_waveset(self):
w = generate_wavelengths(
minwave=3000, maxwave=5000, num=100, log=False)
config.conf.waveset_array = w[0].value.tolist()
config.conf.waveset = w[1]
np.testing.assert_allclose(
[config.conf.waveset_array[0], config.conf.waveset_array[-1]],
[3000, 4980])
assert (config.conf.waveset ==
'Min: 3000, Max: 5000, Num: 100, Delta: None, Log: False')
# Reset to default
config.conf.reset('waveset_array')
config.conf.reset('waveset')
np.testing.assert_allclose(
[config.conf.waveset_array[0], config.conf.waveset_array[-1]],
[500, 25989.72879567])
assert config.conf.waveset == self.def_dict['waveset']
def test_waveset(self):
w = generate_wavelengths(
minwave=3000, maxwave=5000, num=100, log=False)
config.conf.waveset_array = w[0].value.tolist()
config.conf.waveset = w[1]
np.testing.assert_allclose(
[config.conf.waveset_array[0], config.conf.waveset_array[-1]],
[3000, 4980])
assert (config.conf.waveset ==
'Min: 3000, Max: 5000, Num: 100, Delta: None, Log: False')
# Reset to default
config.conf.reset('waveset_array')
config.conf.reset('waveset')
np.testing.assert_allclose(
[config.conf.waveset_array[0], config.conf.waveset_array[-1]],
[500, 25989.72879567])
assert config.conf.waveset == self.def_dict['waveset']
def flat_spectrum(cls, amplitude=0, waves=None):
"""
Creates a flat spectrum in the preferred system scaled to a magnitude,
default a zero magnitude spectrum
Parameters
----------
amplitude: float, u.Quantity
amplitude/magnitude of the reference spectrum, default=0
default is u.ABmag
for vega use u.mag or ``synphot.units.VEGAMAG``
waves: The waveset of the reference spectrum if not Vega
if not provided they will be created at a resolution of R~800
Returns
-------
a Spextrum instance
"""
if waves is None: # set a default waveset with R~805
waves, info = utils.generate_wavelengths(minwave=100,
maxwave=50000,
num=5000,
log=True,
wave_unit=u.AA)
if isinstance(amplitude, u.Quantity) is False:
amplitude = amplitude * u.ABmag
if amplitude.unit is u.Unit("mag") or amplitude.unit is u.Unit(
"vegamag"):
spec = get_vega_spectrum()
spec = spec * 10**(-0.4 * amplitude.value)
system_name = amplitude.unit
else:
const = ConstFlux1D(amplitude=amplitude)
spec = cls(modelclass=Empirical1D,
points=waves.value,
lookup_table=const(waves.value))
system_name = amplitude.unit
spec.repr = "Spextrum.flat_spectrum(amplitude=%s)" % str(amplitude)
return spec
