[amsat-bb] Re: Sun shadow for True North

[Dave Guimont]

>
>>A vertical rod about 4' long (plumb it, or use a level) will have the
>>shortest shadow at noon.

I should have said "near noon".....


>Not necessarily.  Ignoring DST, local solar noon can occur anywhere 
>within a window of around 1 hour (give or take, depending on the 
>exact borders of your local time zone), because each time zone is 
>approximately 15 degrees wide (there are local variations that take 
>the official zones beyond the 15 degree nominal zones).  For 
>example, here in Melbourne, local solar noon usually occurs around 
>approximately 02:15 - 02:20 UTC (12:15 - 12:20 standard time or 
>13:15 - 13:20 DST).  In Brisbane, it occurs before noon AEST, 
>despite both cities being in the same time zone.  Using the 
>"shortest shadow at noon" method, you can have an error of up to 10 
>degrees (now THAT would ruin the performance of your high gain 
>antenna!).  Here, it would be around 4-5 degrees, if one was 
>ignorant of the actual time of solar noon.
>
>The moving shadow to find the East - West line is a much better and 
>MUCH more accurate idea.
>
>73 de VK3JED
>http://vkradio.com



            73, Dave, WB6LLO
                dguimon1 at san.rr.com

                    Disagree: I learn....

               Pulling for P3E...