[LEAPSECS] UT1 offset

[Jim Lux]

Let’s back of the envelope the impact of a 1 second error in a longitude sight.
The Sun moves 360 degrees in 86400 seconds. A one second error is then about 0.004 degree.  But in equatorial km, let’s assume 40,000 km circumference, so 40,000 km in 86,400 seconds (yeah, it’s actually less, sidereal day and all that). Or an error of about 1/2 km.

For the vast majority of boat driving purposes, this is sufficiently accurate - you need to get to within visual range of the coast, so you can get into the desired port.

For flying a plane by celestial navigation, you might care more, because the plane is flying faster than a boat moves.


Sent from my iPad

> On Dec 26, 2023, at 7:10 AM, Gary E. Miller <gem at rellim.com> wrote:
> 
> Yo Hal!
> 
>> On Mon, 25 Dec 2023 00:25:07 -0800
>> Hal Murray <halmurray+leapsecond at sonic.net> wrote:
>> 
>> Who uses DUT1 via radio?  Who will be using it 50 years from now?
>> 
>> Is it needed for anything other than navigation and astronomy?
> 
> I just asked my brother that did a lot of transoceanic navigation
> by sextant.  He did not even know what UT1 is.  He certainly would
> not know what to do with DUTs. 
> 
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>    gem at rellim.com  Tel:+1 541 382 8588
> 
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