astrolibR (version 0.1)

flux2mag: Convert from flux (ergs/s/cm^2/A) to astronomical magnitudes

Description

Convert from flux (ergs/s/cm^2/A) to astronomical magnitudes

Usage

flux2mag(flux, zero_pt=21.10, ABwave)

Arguments

flux

flux, in erg cm-2 s-1 A-1, scalar or vector

zero_pt

zero point level of the magnitude (default = 21.1)

ABwave

wavelength for conversion to Oke AB magnitudes, in Angstroms (optional)

Value

mag

magnitude, scalar or vector

Details

The default zero point of 21.1 mag is from Code et al. (1976). It is ignored of the ABwave parameter is supplied.

If ABwave is not supplied, the routine returns magnitudes given by the expression

mag <- -2.5*log10(flux) - zero_pt.

If ABwave is supplied, then the routine returns AB magnitudes from Oke and Gunn (1983) according to abmag <- -2.5*log10(flux) - 5*log10(ABwave) - 2.406.

Use mag2flux for conversions in the opposite direction.

References

Oke, J. B. and Gunn, J. E., 1983, Secondary standard stars for absolute spectrophotometry, Astrophysical Journal, 266, 713-717

Examples

flux2mag(3e-17)   #  returns 20.21

ytext <- expression(Flux~~ (erg/s~cm^2~A))
plot(seq(2000,5000,length=100), flux2mag(seq(3e-17,3e-16,length=100)), pch=20)