Some constants for approximate conversions between different magnitude scales are also provided:
JOHNSON_AB_*
, for Johnson <-> AB magnitude
conversions
(http://www.astro.utoronto.ca/~patton/astro/mags.html,
citing Frei and Gunn 1995).VEGA_AB_*
, for Vega <-> AB magnitude
conversions
(Blanton et al., Astronomical Journal 127, 2562-2578 (2005),
eqs.(5)).