In message <5.2.1.1.1.20030709091601.01e0d4b0@...>, Bill J Gray
<pluto@...> writes

>     Alan,  could you please describe this "no go" area a bit?
> Am I correct in assuming that it's simply moved from
> "can't go above this altitude without hitting the base" to
> "can't go above this declination without hitting the base"?
>
>     In such a case,  you need simply switch from having
> a red area centered on the zenith to having a red area
> centered on Polaris.  It still won't move relative to the
> horizon,  so it will still work.

Yes Bill, you are right in that I want to draw a big circle around
Polaris. However, I have to admit I haven't the foggiest on how to
centre on Polaris.
Below is the data you gave me before.. can you help?

f 18 48 0 0 ; altitude cap
0 60
20 60
40 60
60 60
80 60
100 60
120 60
140 60
160 60
180 60
200 60
220 60
240 60
260 60
280 60
300 60
320 60
340 60
Alan Cahill
Mount Abbeydale,
Gloucester U.K.
MPC Code J94
http://www.mountabbeydale.pwp.blueyonder.co.uk/