[time-nuts] OT - GPS and North

J. Forster jfor at quik.com
Sun Nov 22 02:13:02 UTC 2009


Not so. I'm very familiar with laying in accurate North lines for gyro
testing. To get anything close to accurate (1 arc second or better) takes
many hours of stellar observation with a Wild T-3 class instrument.

-John

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



> Neville Michie wrote:
>>
>> When you think of time specifications from GPS, the GPS system is a
>> poor way to find north.
>> Even with a base line of 1000 metres you only have a fraction of a
>> degree.
>> The GPS system may be useful to get accurate time to simplify a star
>> observation, from a known (GPS)
>> position on this planet, but finding north is still a problem because
>> of the accuracy of a small
>> number of observations from a star fix.
>> Gyrocompasses take some time to get a measurement
>> ( one hour) but even their estimate of North  cannot match the
>> precision that the GPS system can get us with time.
>> cheers, Neville Michie
> If you are taking star shots a stellar compass can easily provide a
> boresight pointing accuracy of a few arcsec.
>
> Bruce
>
>
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