Some elder friends observe variable stars and do study on the observation.
I thought it was really cool to distinguish the brightness with human
eyes so that I learnt how to do that.
While does observation, we choose two stars(which the magnitude was
sure, not vary so fast as our object) first within the field of binocular.
One should brighter than your object while the other should be fainter.
These three stars better to line in a row 'cuz there'll be less accuracy
if the eyes move left & right than up & down. Then we divide the delta
magnitude of the two reference stars by 10.(some guys use "8") If you feel
the object [fainter than star A] : [brighter than star B] = 2:8(or "1:7"
for 8 divisions), you can record it as A2vB8(or "A1vB7" for 8 divisions
). Now, if the mag of star A is 3.3 and 4.1 for star B, then the mag of the
object should be 3.46(or 3.5 for efficient number consideration).
Although this is not exact at all(the variation of brightness is not linear),
you can learn how to estimate. Professional observation would absolutely
adopt CCD or other instruments, but to observe with the eyes has another
kind of joy^_^
P.S. Backgroung image from "The Sky" skymap
