[time-nuts] Crude Survey Technique

J. Forster jfor at quikus.com
Thu Nov 21 14:11:19 EST 2013


For something that crude, I'd consider taking a sight on Polaris. If you
note the time and do the math, you can probably do better than your
bounds.

Also, there is almost certainly an app somewhere to do the math for you. I
think tha reeuction info was in Bowditch or the Nautical Almanac.

FWIW,

-John

===================





> In message <8D0B5020292D91E-CC0-4B0E1 at webmail-vm026.sysops.aol.com>,
> johncroos@
> aol.com writes:
>
>> I wish to establish a north south line on my property to an
>>accuracy of +/- 2 degrees.
>
> First of all, at that level of precision you will have to decide what
> you mean by "north south" ?
>
> Magnetic ?  Geodetic ?  (if so: Which Datum ?)  Meridian ?
>
>> The base line would be 300 ft
>
> So your east-west precision needs to be tan(2)*300ft = 10.5 ft.
>
> I don't think you can do that with a single band GPS.
>
> If you can locate suitable landmarks, you may be able to do with
> the arial photograph on maps.google.com (or similar servce) but
> you need to get coordinates figured out (not trivial!)
>
> I would raise a pole or other marker at one end (N or S), calculate
> when a suitable celestial object crosses your designated line and
> that to triangulate the opposite end.
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by
> incompetence.
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