Le 20/03/2011 05:59, Bruce Griffiths a écrit :
jimlux wrote:
A 10-12m diameter dish is probably close to the minimum feasible
aperture.
A 4m dish can be made to work in conjunction with a mauch larger dish
(eg 30m).
The original speculation was for measuring the small change in earth
No one has commented on my graph. I would have thought that change
would easily be detected.
Jim
On Sunday, March 20, 2011, cook michael michael.c...@sfr.fr wrote:
Le 20/03/2011 05:59, Bruce Griffiths a écrit :
jimlux wrote:
A 10-12m diameter dish is probably close to the minimum
Le 17/03/2011 22:14, Jim Palfreyman a écrit :
Just for fun I plotted the UT1-UTC data from the IERS Bulletin A.
Here's the raw data:
I add the deltas
UT1-UTC
s delta
-0.18115
-0.182320,00161
-0.183530,00121
-0.1847 0,00117
-0.185760,00116
-0.186740,00098
-0.18763
Le 20/03/2011 11:02, cook michael a écrit :
Le 17/03/2011 22:14, Jim Palfreyman a écrit :
Just for fun I plotted the UT1-UTC data from the IERS Bulletin A.
Here's the raw data:
Ooops - I correct the deltas ...
UT1-UTC
s delta
-0.18115
-0.182320,00117
-0.183530,00121
On 03/20/2011 11:02 AM, cook michael wrote:
Le 17/03/2011 22:14, Jim Palfreyman a écrit :
Just for fun I plotted the UT1-UTC data from the IERS Bulletin A.
Here's the raw data:
I add the deltas
UT1-UTC
s delta
-0.18115
-0.18232 0,00161
-0.18353 0,00121
-0.1847 0,00117
-0.18576 0,00116
On 3/19/11 10:41 PM, Bruce Griffiths wrote:
Bruce Griffiths wrote:
jimlux wrote:
A 10-12m diameter dish is probably close to the minimum feasible
aperture.
A 4m dish can be made to work in conjunction with a mauch larger dish
(eg 30m).
The original speculation was for measuring the small
jimlux wrote:
On 3/19/11 10:41 PM, Bruce Griffiths wrote:
Bruce Griffiths wrote:
jimlux wrote:
A 10-12m diameter dish is probably close to the minimum feasible
aperture.
A 4m dish can be made to work in conjunction with a mauch larger dish
(eg 30m).
The original speculation was for
Hi
Maybe I missed something here. It would hardly be the first time.
If the objective is to come up with a sub 1 ms resolution on observing the
object. And we have chosen this all so indeed we get fast changes. Isn't a
1,000 second integration going to get in the way? If we need the
The beam from the interferometer/phased array can be swept over the sky
by varying the phase shift between the elements during the data
reduction process allowing high resolution imaging.
Compensating for Earth rotation and consequent changes in the
atmospheric delay are necessary. Differential
On 03/20/2011 08:26 PM, Bruce Griffiths wrote:
The beam from the interferometer/phased array can be swept over the sky
by varying the phase shift between the elements during the data
reduction process allowing high resolution imaging.
Compensating for Earth rotation and consequent changes in the
Hi
I have no doubt that VLBI works. I'm also quite confident that with great big
dishes and fancy attachments you can do a really good job. My confusion is more
as this relates to the back yard time the earth to 1 ms (or 1 us) question.
Of the files that downloaded for me, the pptx file has
Hi
If the signal is actually 80 db below the noise, you will need a lot of cross
correlation simply to find it at all. Your digitizers are going to have to be
*very* good just to let you get that far in the first place.
Bob
On Mar 20, 2011, at 6:36 PM, Magnus Danielson wrote:
On 03/20/2011
jimlux wrote:
A 10-12m diameter dish is probably close to the minimum feasible
aperture.
A 4m dish can be made to work in conjunction with a mauch larger dish
(eg 30m).
The original speculation was for measuring the small change in earth
rotation rate, for which some sort of
Bruce Griffiths wrote:
jimlux wrote:
A 10-12m diameter dish is probably close to the minimum feasible
aperture.
A 4m dish can be made to work in conjunction with a mauch larger dish
(eg 30m).
The original speculation was for measuring the small change in earth
rotation rate, for which
Chris Albertson wrote:
On Wed, Mar 16, 2011 at 11:00 PM, jimluxjim...@earthlink.net wrote:
Could you make the measurement in, say, 48 hours.. A portable setup might be
reasonable with a 10-20km baseline.
Before you can even think about building a long baseline radio
receiver the
On 3/17/11 12:30 PM, Chris Albertson wrote:
On Wed, Mar 16, 2011 at 11:00 PM, jimluxjim...@earthlink.net wrote:
Synchronizing the several receivers that are spread aroud is not
really even required. Many years ago astronomers would mail magnetic
tapes and the data would be combined days
A 10-12m diameter dish is probably close to the minimum feasible aperture.
A 4m dish can be made to work in conjunction with a mauch larger dish
(eg 30m).
The original speculation was for measuring the small change in earth
rotation rate, for which some sort of interferometric measurement
On 3/16/11 11:31 AM, Chris Albertson wrote:
On Wed, Mar 16, 2011 at 1:14 AM, Hal Murrayhmur...@megapathdsl.net wrote:
Your pointing accuracy is Y/X, or something close to that.
That describes perfectly when radio can beat optics. The angular
resolution of the system is the aperture size
On Wed, Mar 16, 2011 at 11:00 PM, jimlux jim...@earthlink.net wrote:
Could you make the measurement in, say, 48 hours.. A portable setup might be
reasonable with a 10-20km baseline.
Before you can even think about building a long baseline radio
receiver the first goal is to be able to detect a
Just for fun I plotted the UT1-UTC data from the IERS Bulletin A.
Here's the raw data:
UT1-UTC
s
-0.18115
-0.18232
-0.18353
-0.1847
-0.18576
-0.18674
-0.18763
-0.18842
-0.18912
-0.1897
-0.1903
-0.19103
-0.192
-0.19324
This is from March 4 to Match 17 inclusive.
I don't know if it's a fluke, but
jimlux wrote:
On 3/15/11 9:36 PM, Hal Murray wrote:
If I were doing this in my backyard on a budget I'd mount a small
telescope nearly straight up so that a bright star would pass through
the field on several nights. I'd measure the light of the star
through a slit and time the peak of the
Couldn't you rig up a MLBI (medium, not very) setup between you and someone
else in your area..
Could one detect pulses (or a signal) from some quasar (or infinite
distance stellar source) with a reasonable small antenna.
Suppose you have two antennas X seconds (at speed-of-light) apart
On 3/15/11 11:08 PM, Bruce Griffiths wrote:
jimlux wrote:
On 3/15/11 9:36 PM, Hal Murray wrote:
If I were doing this in my backyard on a budget I'd mount a small
telescope nearly straight up so that a bright star would pass through
the field on several nights. I'd measure the light of the
On 03/16/2011 02:25 PM, jimlux wrote:
Or, you can send a signal between the two stations by an RF link. If I
recall correctly, you'd need to compensate for propagation variations,
but, a two way scheme might work for that. I think I have a paper
somewhere that talks about how they did that for
On Wed, Mar 16, 2011 at 1:14 AM, Hal Murray hmur...@megapathdsl.net wrote:
Your pointing accuracy is Y/X, or something close to that.
That describes perfectly when radio can beat optics. The angular
resolution of the system is the aperture size over the wavelength.
So you can see that a radio
[snip] but technology exists to build a radio
antenna array that is one Earth diameter wide. So radio wins if you
have a government or university sized budget [snip]
Yes. Been done. It's called VLBI.
-John
=
___
time-nuts mailing
Hi
Since you are going for time transfer, ping pong on a single channel should do
pretty well. With some clever design you could locally receive your transmitted
packet. You would drop out a lot of local detuned coil issues that way. A
lot would depend on just how far you needed to stretch
Hello,
Firstly may I just say, my thoughts are with members of this list who
are in Japan.
Just a bit of an odd question...
I hear in the Media that the earth quake sped the rotation of the earth
up..
Can anyone confirm this?
Does this mean that we will not need to 'insert leap seconds' for a
I hear in the Media that the earth quake sped the rotation of the earth up..
http://tinyurl.com/4pwgkte
http://earthsky.org/earth/richard-gross-japan-earthquake-shortened-earths-day-
1-8-millionths-of-a-second
It says:
shortened Earth's day by 1.8 millionths of a second
Here is the JPL/NASA
Just a bit of an odd question...
I hear in the Media that the earth quake sped the rotation of the earth
up..
Can anyone confirm this?
Any time any mass shifts inwards or outwards from the Earth's center,
there will be a change in the rotational speed of the planet. Angular
momentum must be
On 3/15/11 1:49 AM, Chris H wrote:
Hello,
Firstly may I just say, my thoughts are with members of this list who
are in Japan.
Just a bit of an odd question...
I hear in the Media that the earth quake sped the rotation of the earth
up..
Can anyone confirm this?
Yes, the media reported it.
On 3/15/11 6:20 AM, jimlux wrote:
On 3/15/11 1:49 AM, Chris H wrote:
I hear in the Media that the earth quake sped the rotation of the earth
up..
Can anyone confirm this?
No.. the magnitude of the change is parts in 1E11 or thereabouts.
Regular old tidal drag slowing is bigger, and that's
One simple calculation is the ratio of the total rotational energy of
the planet (which is simple to calculate) to the energy release of
the earthquake.
The magnitude of the earthquake probably has a relation to the total
energy release. This must put an upper limit on the change of time.
I suspect somebody plugs the vertical movement data into a model and
microseconds come out.
Bob
On Mar 15, 2011, at 7:07 PM, Neville Michie namic...@gmail.com wrote:
One simple calculation is the ratio of the total rotational energy of the
planet (which is simple to calculate) to the
Does anyone here know the current state of the art for timing the
Earth's rotation?I know the outline, An instrument on a transit
telescope notes the time when a star passes overhead. You take many
of these observations and you can determine the period
What is the instrument of choice? Is
Does anyone here know the current state of the art for timing the
Earth's rotation?I know the outline, An instrument on a transit
telescope notes the time when a star passes overhead. You take many
of these observations and you can determine the period
Radio VLBI of Quasars comes to
More -
Polar motion can be determined pretty well from ground-based observations
of GPS satellites, period. However, UT is not well determined from
observations of GPS satellites alone, because the entire GPS constellation
may rotate in longitude with respect to an inertial frame. This rotation
Still more:
Subject: Re: [time-nuts] Result of Earth Quake speeds up earth?
From:Chris Albertson albertson.ch...@gmail.com
Does anyone here know the current state of the art for timing the
Earth's rotation? ...
What is the instrument of choice?
The instrument of choice, chosen
I suspect somebody plugs the vertical movement data into
a model and microseconds come out.
I think you skipped over step 0:
Spend N years building a decent model.
--
Has anybody seen any good data on ground motion from this event?
[The Chile quake had a really good monitoring
If I were doing this in my backyard on a budget I'd mount a small
telescope nearly straight up so that a bright star would pass through
the field on several nights. I'd measure the light of the star
through a slit and time the peak of the light each night. I bet I
could get to about a
On 3/15/11 9:36 PM, Hal Murray wrote:
If I were doing this in my backyard on a budget I'd mount a small
telescope nearly straight up so that a bright star would pass through
the field on several nights. I'd measure the light of the star
through a slit and time the peak of the light each
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