vertex angle, TiPS

Jay Respler (jrespler@injersey.com)
Thu, 25 Jul 1996 23:31:26 -0400 (EDT)

I don't agree about the lack of agreement:

>There seems to be a lack of agreement between surveying and astronomy on 
>the name of the angle and the definition (see appendices).

>... vertex angle in occultation predictions ... is measured like 
>position angle, but 0 is the local vertical direction, rather than north. 
>Hence, 0 deg. is up, 90 is to the left, 180 is down, and 270 is to the 
>right. 

The astronomy angle is one of rotation, counterclockwise from the top.

>Zenith Distance 
> 
>The zenith distance is a vertical angle measured from directly overhead, down 
>to the required point.  An ideal horizon has a zenith distance of 90 degrees. 
> 
>Vertical angle 
> 
>The Vertical angle is the angle measured in a vertical plane, from the horizon 
>to the required point.  Directly overhead would have a vertical angle of 90
degrees.

The survey angle just measures elevation.  It has nothing to do with rotation
or the apparent angle of Tips.

Jay Respler
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