# Mean surface brigthness within 25 mag isophot (B-band): bri25

`bri25` (or `amp25`) is the apparent brightness : `B + 5logD +3.63 + as `

where B is the apparent magnitude in the B-band,
logD is the `logd25` diameter and

`as` is the inclination correction in magnitude per squared arcsec and is
calculated as given below:

`R` is the axis ratio derived from `logr25`

`k` is the bulge to disk ratio and depends on morphological type as follows: `k=0.754*10`^{(-0.2*t)},
`if k >1 then k=1` (Simien and de Vaucouleurs)

`K` is the coefficient `dlogD/db` (where `D` is the isophotal diameter at surface brightness `b`).
It depends on the morphological type `t` as:

`K = 0.12-0.007*t if t < 0.`

`K = 0.094 if t >= 0.`

and `C` is defined as `(dlogD/dlogR)` and has the fixed value of 0.04
according to
Bottinelli et al. 1995, A&A296, 64.