3.1 Magnitudes
µ = B(0) - MG(n), where B(0)
is the B magnitude in the standard
system of the Reference Calalogue, and MG(n) =
M0 + 0.5n (n
5), with
| M0 | = -20.0 for types E, L, and S0-S7 (i.e., S0/a to Sd), |
| = - 19.5 for types S8, S9 (Sdm, Sm) | |
| = -19.0 for type I9 (= Im). |
The luminosity classes of spirals (van den Bergh 1960a) were also used where available with the following calibration (after van den Bergh, but adjusted to fit the latest data on the Local Group):
| Class | I | I-II | II | II-III | III | III-IV | IV | IV-V | V |
| L | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| -MG | -19.95 | -19.45 | -18.95 | -18.45 | -18.00 | -17.55 | -16.85 | -15.65 | -14.00 |
Here again MG is on the B(0) system.
N.B. The total (asymptotic) magnitude is about 0.5 mag less than B(0) depending on galaxy type (0.67 at type E, 0.33 at Im).