# Calculate the Absolute Magnitude of Sun I Band

The calculator calculates the absolute magnitude of sun I Band.

It calculates absolute magnitude of sun I band based on the observed maximum rotation velocity and galactic inclination. Tully-Fisher relation was published by R. Brent Tully and J. Richard Fisher in 1977. It is a relationship between intrinsic luminosity of spiral galaxy and the width of its emission lines.

**Formula:**

_{I}≃ -7.68 log

_{10}(2v

_{rot}/ sin i) - 2.58

**Where,**

M_{I} = Iband Absolute Magnitude,

v_{rot} = Observed Maximum Rotation Velocity,

i = Galactic Inclination

### Difference between apparent and absolute magnitude

The apparent magnitude measures the brightness of the star observed from any point, in otherhand absolute magnitude measures the brightness of the star observed from a standard distance away that is 32.58 light years.