In principle one could time tag each individual photon with subnanosecond
resolution.
Bruce
> On 29 March 2019 at 09:00 Poul-Henning Kamp wrote:
>
>
>
> In message <236772484.9174006.1553757616...@webmail.xtra.co.nz>, Bruce
> Griffith
> s writes:
>
> >However when used with a CCD
Hi
I randomly came across:
Publications of the United States Naval Observatory
January 1, 1900
U.S. Government Printing Office
Which turns out to be a Google E-Book. It goes into some detail about just how
the transit
data contained in it was obtained. For the (free) price it’s worth taking a
In message <236772484.9174006.1553757616...@webmail.xtra.co.nz>, Bruce Griffith
s writes:
>However when used with a CCD camera or equivalent the accuracy
>should improve somewhat much as adding a TV camera to a transit
>circle improved its accuracy.
You know ... there *is* an official
Brooke
Yes but the accuracy would suffer due to observer related effects.
However when used with a CCD camera or equivalent the accuracy should improve
somewhat much as adding a TV camera to a transit circle improved its accuracy.
I had a personal tour of the USNO setup on Black-
Relative to Harrison's method of star position measurement and timing, and
the
possible effects of diffraction thereof:
Hanbury Brown's book "The Intensity Interferometer" may provide some useful
insight about various error sources, even though in a different context,
that of
measurement of a
On Wed, Mar 27, 2019 at 2:00 AM jimlux wrote:
>
>
> To get 1 second accuracy, you need 360/86400 = 0.004 degree
> measurements. That's 0.073 milliradian - 1 cm at 140 meter distance.
>
> I'm not sure an "edge" is sharp enough (diffraction, etc.), although
> your eye is pretty good at
There is a large period literature on ³dialing² which not only included
sundials, but all sorts of ways to measure time from celestial objects
using angles. Discussions of trigonometry, surveying, navigation, and
³dyaling² in relationship were also quite common during the period. These
could be
Hi Bruce:
Would the David White 60 Degree Pendulum Astrolabe also work?
https://prc68.com/I/PendulumAstrolabe.shtml
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
axioms:
1. The extent to which you can fix or improve something will be
Of course the time scale will be much shorter for a star occulted by an edge
etc on Earth.
The longer time scale for a lunar occultation is due to the slower relative
angular motion of the moon with respect to the star than the motion of the
Earth with respect to a star.
Bruce
> On 27 March
These light curves for a star being occulted by the moon should give some idea
of the effects of diffraction:
http://tdc-www.harvard.edu/occultations/moon/vb141occa.html
Bruce
> On 27 March 2019 at 15:48 Tom Van Baak wrote:
>
>
> BobH wrote:
> >> This would be an excellent project for
On Wed 2019-03-27T16:26:09+1300 Bruce Griffiths hath writ:
> The Danjon impersonal astrolabe is perhaps better suited to accurate
> measurements:
> https://www.nzmuseums.co.nz/collections/3267/objects/3380/astrolabe
Danjon became director of Observatoire de Paris (and thus also the
BIH) in 1945.
The Danjon impersonal astrolabe is perhaps better suited to accurate
measurements:
https://www.nzmuseums.co.nz/collections/3267/objects/3380/astrolabe
Bruce
> On 27 March 2019 at 15:48 Tom Van Baak wrote:
>
>
> BobH wrote:
> >> This would be an excellent project for time-nuts to verify.
Greetings time-nuts,
Harrison's method depends on the star having the same true azimuth at 1
Sidereal day intervals (23 hours 56 minutes 04 seconds). It does not depend on
a visible horizon since the altitude (which changes with the season) is not
relevant except that one must be able to see
BobH wrote:
>> This would be an excellent project for time-nuts to verify. First, a
>> better explanation of John Harrison’s method is in order. A vertical
>> window edge is not sufficient - a second vertical reference at a
>> distance is required - Harrison used a chimney on a neighbor's house.
On 3/26/19 3:48 PM, Bob Holmstrom wrote:
Ben Bradley stated > "Perhaps closer to your question: I recall in my
readings about clockmaker John Harrison (likely either in "The Quest
for Longitude” or Dava Sobel's "Longitude") that he would look from
the edge of his window at a particular star each
On 3/26/19 4:27 PM, Neville Michie wrote:
It must be a sign of the dedication that Harrison applied to his work.
It is not as simple as the description first appears, this is England,
and the method presupposes that there are no clouds. It might be a week
or two before two nights occurred, when
It must be a sign of the dedication that Harrison applied to his work.
It is not as simple as the description first appears, this is England,
and the method presupposes that there are no clouds. It might be a week
or two before two nights occurred, when an unclouded night was followed
by another
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