## Length of Star Trail

## $$\frac{f*e*\frac{(2\Pi )}{t}*\mathrm{cos}(d*\frac{\Pi}{180})*1000}{p}$$

The values needed for solving this formula are : f = focal length of lens scope, e = exposure length, l = length of sidereal day, in same units as the e, d = declination of the star. if you do not want the end unit to be pixels as you are not using CCD, then place p = 1

ENTER THE VARIABLES TO BE USED IN THE FORMULA