
Interstellar extinction using a tridimensional galactic model
 
Fill in this form in order to compute the extinction, colour
and distance, using the Arenou, Grenon, Gómez (1992) model and
the SchmidtKaler (1982) calibrations.
The same form allows to compute various things, depending on the method:
 If "extinction from V mag and BV": the absorption model is not used:
the colour excess is computed using (BV)_{0} (from spectral type)
and (BV), giving the extinction, then from the apparent magnitude
and the absolute magnitude (from spectral type), the distance is known.
The fields "V mag", "BV" and "Spectral type" are mandatory.
The fields "galactic longitude l", "galactic latitude b",and "distance" are not used.
 If "extinction from V mag and model": the spectral type gives the absolute magnitude,
the distance r is thus computed from apparent and absolute magnitude, the
extinction computed using the (l,b,r) tridimensional model and the colour
from intrinsic colour (from spectral type) and reddening.
The fields "V mag", "gal. l" , "gal. b" and "Spectral type" are mandatory.
The fields "BV" and "distance" are not used.
 If "extinction from l,b and distance": you just want to know the extinction at
a given (l,b,r).
The fields "gal. l" , "gal. b" and "distance" are mandatory.
The fields "mV", "BV", "spectral type" are not used.
Warning: this model is quite old. For better results, you may
consider instead to get the fundamental
parameters of a star from uvbyß photometry
/cgibin/afm  $Revision: 1.1 $
Biblio: Arenou Frédéric, Grenon Michel, Gómez Ana, 1992, Astron. Astrophys. 258, 104111