Working with standard magnitudes in SkyMap

From: Matson, Robert (
Date: Fri May 10 2002 - 14:35:35 EDT

Hi Kevin,

> Can someone check to see if I am going crazy.
> Try the following geo sat as an example
> Galaxy 11                      40.0 v
> 1 26038U 99071A   02128.82175324  .00000000  00000-0  10000-3 0  6463
> 2 26038   0.0783  74.4544 0006274 213.6969 143.1828  1.00268196  8808

SkyMap is not going to "read" that 40.0 as a visual magnitude
since the line is not in the proper Molczan format.  The
standard visual magnitude must be preceded by the three
satellite dimension values in meters.  (Mind you, SkyMap
doesn't do anything with those dimensions, but they still
nevertheless need to be in there because SkyMap was written
to be compatible with Ted's format.)

Also, you should know that 40.0 is not a reasonable standard
magnitude.  If you do the math, that would correspond to an
object about the size of a bacterium.  The actual standard
magnitude for an object like Galaxy 11 is probably in the
3 to 5 range -- Mike McCants would be able to tell you.

If you just want to make sure that SkyMap doesn't filter out
an object like Galaxy 11 that doesn't have a standard magnitude
in the SATMAG.DAT file (or has a placeholder value of 99.9),
just set the default standard magnitude to something like
+3.0.  Alternatively, you can change the nameline to
something like:

Galaxy 11  1.0 0.0 0.0 3.0

and make sure the lighting constraint toggle is set to
read standard magnitudes from the ephemeris file.


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