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Дата изменения: Mon Dec 23 18:23:59 2013
Дата индексирования: Fri Feb 28 17:00:55 2014
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HyperLEDA documentation : parameter: bvt

Corrected apparent B-magnitude: btc

Apparent B-mag bt corrected for galactic extinction, ag, internal extinction, ai and k-correction ak.

btc = bt - ag - ai - ak(t).v/10000.

ak(t), coefficient for the k-correction, is taken from de Vaucouleurs et al (1976, RC2 p33 rel.25)
and v is the heliocentric radial velocity in km.s-1

In practice ak(t), where t is the morphological type, is tabulated as follows:
ak(-5)=0.15
ak(-4)=0.15
ak(-3)=0.15
ak(-2)=0.15
ak(-1)=0.15
ak(0)=0.15
ak(1)=0.125
ak(2)=0.100
ak(3)=0.075
ak(4)=0.065
ak(5)=0.055
ak(6)=0.045
ak(7)=0.035
ak(8)=0.025
ak(9)=0.015
ak(10)=0.005

When unknown, v is assumed to be 0, i.e. no k-correction is applied, and when t is not known, a value of 2 (mean morphological type in the database; spiral galaxy) is assumed. ai is taken as 0 when unknown.
btc is not computed when v > 30000 km/s or bt or ag is unknown.
HyperLeda Questions: leda@univ-lyon1.fr