A) to astronomical magnitudes
In astrolibR: Astronomy Users Library

Description Usage Arguments Details Value Author(s) References Examples

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

1	flux2mag(flux, zero_pt=21.10, ABwave)

`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)

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.

mag

magnitude, scalar or vector

Converted to IDL from Yeoman's Comet Ephemeris Generator, B. Pfarr, STX, 1988

R adaptation by Arnab Chakraborty (June 2013)

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

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)