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From: Leap Second Discussion List
Sent: Jan 3, 2024 9:38 PM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] UT1 offset
Hello all:
A couple of days ago, I started to draft a response to the question raised but
got waylaid. I think others have already address the issue fairly well
|Fredericton? Where's that? See: http://www.fredericton.ca/ |
> ---------
>
>
> From: LEAPSECS on behalf of Tom Van Baak
>
> Sent: January 2, 2024 10:
http://www.fredericton.ca/ |
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From: LEAPSECS on behalf of Tom Van Baak
Sent: January 2, 2024 10:44 AM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] UT1 offset
✉External message: Use caution.
Hi Mike,
> the system needs an estimate of current UT1
Can you
of Tom Van Baak
>
> Sent: 02 January 2024 14:44
> To: Leap Second Discussion List
> Subject: Re: [LEAPSECS] UT1 offset
>
> Hi Mike,
>
> > the system needs an estimate of current UT1
>
> Can you give some references to your observation? I don't recall seei
Most spacecraft don’t know any sort of time in an absolute time scale. They
have a free running counter at some rate, and everything is done in terms of
SCLK. (Spacecraft Clock). Someone on the ground does a process called “time
correlation” to relate local clock on spacecraft to some other
Yo Tom!
On Tue, 2 Jan 2024 06:44:01 -0800
Tom Van Baak wrote:
> Can you give some references to your observation? I don't recall
> seeing UT1 mentioned in the first couple of decades of GPS
> documentation. The system runs on GPS time, the WGS84 coordinate
> system, broadcast ephemeris
Hi Tom and Mike and all,
I suppose we weren’t talking about DUT1 time signals?
See http://futureofutc.org/2011/program/presentations/AAS_11-675_Malys.pptx.pdf
for details about the flipside question of operating a GNSS constellation
(current as of a dozen years ago).
One shouldn’t find it
: [LEAPSECS] UT1 offset
Hi Mike,
> the system needs an estimate of current UT1
Can you give some references to your observation? I don't recall seeing UT1
mentioned in the first couple of decades of GPS documentation. The system runs
on GPS time, the WGS84 coordinate system, broadcast epheme
Hi Mike,
> the system needs an estimate of current UT1
Can you give some references to your observation? I don't recall seeing
UT1 mentioned in the first couple of decades of GPS documentation. The
system runs on GPS time, the WGS84 coordinate system, broadcast
ephemeris including SV clock
On Thu 2023-12-28T09:23:30+ Poul-Henning Kamp hath writ:
> Also: When celestial navigation is possible, most vessels
> travel a lot further than 50 meters during the time it takes to make
> a measurement of the necessary precision.
As noted by ION
Warner Losh writes:
> Still, even 50m can be a lot if you are flying over a narrow mountain pass
> in a plane that can't just fly super-high above it...
Celestial navigation requires you to be able to see something through the
windows.
If that is an option the sane pilot would look at
is that knowledge of UT1
(i.e. the spin phase of the Earth) is essential for GNSS - and many other space
systems.
Mike
From: LEAPSECS on behalf of Jim Lux
Sent: 26 December 2023 15:40
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] UT1 offset
Let’s back
On Wed, Dec 27, 2023 at 6:04 AM Jim Lux wrote:
> 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
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,
Yo Hal!
On Mon, 25 Dec 2023 00:25:07 -0800
Hal Murray 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
On Mon 2023-12-25T00:25:07-0800 Hal Murray hath writ:
> Who uses DUT1 via radio? Who will be using it 50 years from now?
>
> Is it needed for anything other than navigation and astronomy?
UT1 is not needed for navigation if the almanacs switch their
tabulations to use the time scale that is
>>> . Please keep DUT1 less than 100 seconds.
>> They /really/ dont want to ever see a leapsecond or leapminute, do they ?
> I'd love for them to have 6 digits for the offset.. .99.
Why try to make that field big enough? Why not just drop it?
Who uses DUT1 via radio? Who will be using
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