NavList:

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From: George Huxtable <george@hux.me.uk>
To: navlist@fer3.com
Sent: Sun, November 8, 2009 11:38:50 AM
Subject: [NavList 10503] Re: 2-Body Fix -- take three

[parts deleted by PH]

Now for a separate issue, if John will forgive me for adding another twist.
I can't resist bringing out an old hobby-horse of mine once again,
concerning 7.5f. John wrote-
"We're using the convention that LHAs are measured westward to 360, and that
west Lons are negative."

Some reader-confusion is added because we are having to add or subtract
amounts, longitude and hour-angle, which are of the same quantity (angle
measured with respect to the Earth's polar axis) but which are defined as
going positive in opposite directions. I wonder if anyone can think of
another example, in any field of mensuration, where this occurs? I can't.

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this comes from:
Lon = - ( GHA1 - LHA1 )
in which the expression in () is self-evident and the extra minus sign addresses the sign convention.  This should address any possible confusion.

Combining Arabic script and numerals has a left-to-right vs. right-to-left issue.


Peter Hakel