Re: Orientation format
Jim Varney (jvarney@mail2.quiknet.com)
Wed, 14 Aug 1996 22:33:31 -0700
Walter Nissen wrote:
>I have made some important changes in the details of the format which I
>propose for reporting orientation (of tethers).
>I suggest this convention. Assume that the observer is able to
>distinguish Ralph from Norton. If the orientation is, e.g.:
>
>then the vertex angle is:
>
...
>
>and the observer should report a vertex angle between 0 and 359.99
>degrees. I.e., the vertex angle (see appendix) of Norton with respect to
>Ralph, i.e, the angle measured counter-clockwise from directly above.
>
>If the observer cannot distinguish Ralph from Norton, then the angle reported
>should be a vertex angle, determined in the same way, between 0 and 179.99
>degrees.
My personal opinion is that the "20 degrees Lower Mass Leading" convention
is preferred. It abbreviates to a short, elegant "20 deg LML." I also
like the "LML" or "LMF" format because it translates very naturally from
what we actually observe -- deviation from apparent vertical.
Vertex angle is usually not measured from the apparent vertical. To create a
new definition of vertex angle with a different coordinate reference might
introduce confusion.
In the engineering world the term for deviation from vertical is "slope."
A vertical slope is a 90 degree slope; so 20 deg LML would be reported as
70 deg, while 20 LMF would be noted as 110 degrees. This would work,
but it seems awkward in comparison to the "LML" convention.
-- Jim
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Jim Varney | 121^ 23' 54" W, 38^ 27' 28" N | Sacramento, CA
Member, SeeSat-L| Elev. 31 ft. |jvarney@mail2.quiknet.com
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