# Re: Standard magnitude

From: Bjoern Gimle (b_gimle@algonet.se)
Date: Thu Dec 21 2000 - 12:35:18 PST

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```This formula is of little help in the current discussion, since as it stands
the quantity C simply represents the relative brightness, for which we want
to find a formula from the known angles.

(If C is 0.1, the magnitude is +2.5 from its maximum 100% value, which is
trivial)

The known angle is usually sun-satellite-observer  ( 0 at full phase) or
sun-observer-satellite (180 degrees at full phase), and the standard
magnitude is for 90 degrees (SkyMap) or full-phase (QuickSat)

> > For example, let's say a new satellite is observed at magnitude
> > +5.0 at precisely 1000-km slant range (to remove range from
> > the equation), and 75% "illumination", which I take to mean
> > a sun-satellite-observer angle of 45 degrees.  What is this
> > satellite's standard magnitude?  (The correct answer is +5.94).
>
> According to the formula
> A - 15.75 + 2.5 x log (BxB/C),
> If I input 5.94 for A, 1000km for B, and 75% for C, I get +5.50.
> Conclusions?

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