spectral_density_vega¶
- sbpy.units.spectral_density_vega(wfb)[source]¶
Flux density equivalencies with Vega-based magnitude systems.
Uses the default
sbpy
Vega spectrum, orvega_fluxd
.Vega is assumed to have an apparent magnitude of 0 in the
VEGAmag
system, and 0.03 in the Johnson-Morgan,JMmag
, system [Joh66, BM12]_.- Parameters
- wfb
Quantity
,SpectralElement
, string Wavelength, frequency, or a bandpass of the corresponding flux density being converted. See
from_filter()
for possible bandpass names.
- wfb
- Returns
- equivlist
List of equivalencies.
References
[Joh66] Johnson et al. 1966, Commun. Lunar Planet. Lab. 4, 99
[BM12] Bessell & Murphy 2012, PASP 124, 140-157
Examples
Monochromatic flux density: >>> import astropy.units as u >>> from sbpy.units import spectral_density_vega, VEGAmag >>> m = 0 * VEGAmag >>> fluxd = m.to(u.Jy, spectral_density_vega(5557.5 * u.AA)) >>> print(fluxd) # doctest: +FLOAT_CMP 3544.75836649349 Jy
Use your favorite bandpass and zeropoint (Willmer 2018): >>> from sbpy.calib import vega_fluxd >>> cal = {‘SDSS_r’: 3255 * u.Jy, ‘SDSS_r_lambda_pivot’: 0.6176 * u.um} >>> with vega_fluxd.set(cal): … fluxd = m.to(u.Jy, spectral_density_vega(‘SDSS_r’)) … print(fluxd) # doctest: +FLOAT_CMP 3255.0 Jy
Use your favorite bandpass and zeropoint (Willmer 2018): >>> from sbpy.calib import vega_fluxd >>> cal = {‘SDSS_r’: 3255 * u.Jy, ‘SDSS_r_lambda_pivot’: 0.6176 * u.um} >>> with vega_fluxd.set(cal): … fluxd = m.to(u.Jy, spectral_density_vega(‘SDSS_r’)) … print(fluxd) # doctest: +FLOAT_CMP 3255.0 Jy