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Most standard magnitudes are derived from actual observations, after (approximate) conversion to 90 or 180 degrees phase, probably using ln(1-cos(phase) and 5*log10(range) as correction terms. Also there are different preferences re using max or average magnitude. See http://www.io.com/~mmccants/tles/intrmagdef.html Rob Matson's SkyMap can use the standard magnitude on elset Line0 or in its SKYMAP.DAT file. The SKYMAP.DAT can also contain Radar Cross Sections, which are converted to standard magnitudes internally. From dimensions, surface form and properties "conversion" is very difficult, but I believe that a white sphere of 1 m2 cross-section is +6.4 /Björn ----- Original Message ----- >I am interested in how standard magnitude is calculated. I have been > unable to find information on this exact calculation beyond the fact > that it is based on the surface area of the spacecraft and some > assumptions about the surface properties. > > I cannot find further definition beyond what is mentioned here: > http://www.io.com/~mmccants/tles/mccdesc.html ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html

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