RE: Calculating magnitudes

Matson, Robert (ROBERT.D.MATSON@cpmx.saic.com)
Thu, 15 Oct 1998 17:49:10 -0700

Bjoern wrote in reply to Philip's question about magnitude
calculation:

> I have an old note that rm is 6.0 - 2.5*log(Area*albedo), but
> those factors are rarely known for satellites, so empirical
> rm is preferred.

> If full moon is -12.8, it needs rm = -24.9, which gives an
> albedo of 0.25!  Half moon would be -12.0, and one day moon
> (ph=12 d) -7.8.  Something does not quite right there.

The problem here is that the moon is very non-Lambertian.  A first
quarter or third quarter moon is much less than half as bright as
a full moon.   --Rob