In message <5.2.1.1.1.20030709184606.026a5090@...>, Bill J Gray
<pluto@...> writes

> Hi Alan,
>
>     Aha!  OK,  now I see what you're driving at.
>
>     The problem is one of determining some alt/az points
> surrounding that big 30-degree diameter disk centered on
> Polaris.  Knowing your MPC code gave me your latitude;
> I reset to that,  then centered Guide on assorted points
> at declination +60,  at 1h30m intervals in RA.  That gives
> sixteen points;  in reality,  I looked at eight,  noting the
> alt/az for each.  Then I mirror-imaged them to get the
> remaining eight.  So you now have a sixteen-point polygon,
> not eighteen,  and the values are
>
> f 16 48 0 0 ; altitude cap
>    4.8 22.0
>   16.7 24.7
>   27.8 30.0
>   37.8 37.5
>   46.2 46.8
>   52.3 57.4
>   53.5 68.6
>   37.3 78.9
> -37.3 78.9
> -53.5 68.6
> -52.3 57.4
> -46.2 46.8
> -37.8 37.5
> -27.8 30.0
> -16.7 24.7
>   -4.8 22.0

Bill,

Thanks for that.. however, perhaps I'm missing something.. because all I
get is almost a semi circle, in red. Not a full circle around Polaris.
Am I doing something wrong?

Cheers

Alan

Alan Cahill
Mount Abbeydale,
Gloucester U.K.
MPC Code J94
http://www.mountabbeydale.pwp.blueyonder.co.uk/