>> Ordinary? You mean something like a Wild T-2 or Kern DKM-2. Even then
>> getting close to 1 arc-second requires a lot of care.
>
> A wild T1 reads directly to 6 seconds, but with repetition will get 1
> second.
> Unlike digital instruments you need a little bit of skill and
> persistence to get
On 26/01/2012, at 2:49 AM, J. Forster wrote:
Finding your location without GPS is not all that difficult.
You need a quality theodolite, but even an ordinary one will read to
1 second of arc.
Ordinary? You mean something like a Wild T-2 or Kern DKM-2. Even then
getting close to 1 arc-second r
> Finding your location without GPS is not all that difficult.
> You need a quality theodolite, but even an ordinary one will read to
> 1 second of arc.
Ordinary? You mean something like a Wild T-2 or Kern DKM-2. Even then
getting close to 1 arc-second requires a lot of care.
> You observe circum
Finding your location without GPS is not all that difficult.
You need a quality theodolite, but even an ordinary one will read to
1 second of arc.
You observe circumpolar stars at night to obtain a true azimuth.
(North and South)
and also the latitude by the inclination of the pole.
On a time
On 1/24/12 3:19 PM, J. Forster wrote:
Is the USNO almana/ephemeris still published in hard copy every year? That
had moon timing, etc.
You can download pieces from the Astronomical Applications website at USNO.
Or you can buy a copy of the Nautical Almanac for about $20 from a
variety of sou
On 1/24/12 10:26 AM, Chris Albertson wrote:
have you ever tried to measure an angular distance using a hand held
instrument while standing on the deck of a moving boat in the open
ocean? try it and you will see why they wanted a clock. You
really can't measure an arc minute reliably we shoul
On 1/24/12 9:46 AM, Attila Kinali wrote:
On Tue, 24 Jan 2012 11:05:58 -0600
"Lee Mushel" wrote:
If you're looking for a really interesting topic to read about, the
development of an accurate ship-board clock is really fascinating! And it
wasn't done overnight!
If you have a few references
On 1/24/12 9:48 AM, Chris Albertson wrote:
If you want to try your hand at position determination in the pre
radio nav days you can buy a "studen sextent" It's a low cost plastic
instrument sells for about $60.
That's the Davis Mark 3 (which is basically a copy of a lifeboat
sextant). $50 from
For a rough determination; you are facing due south, or due north when the
elevation of a celestial body stops increasing with time. The elevation is
highest when the body is on the observer's local meridian. There are
exceptions, for instance when observing a body below Polaris, then the body
Hi:
The basic way to find your location anywhere in the world is to use a photo
sensor.
This is the method used on tagged fish. The light level is logged and time stamped probably using a watch crystal.
When the fish is caught the logger data is read out.
Have Fun,
Brooke Clarke
http://www
Is the USNO almana/ephemeris still published in hard copy every year? That
had moon timing, etc.
-John
===
-John
>
>> But how do you untangle longitude and time? How do you know that you are
>> looking exactly south (or north)?
>
> If I understand what you are aski
> But how do you untangle longitude and time? How do you know that you are
> looking exactly south (or north)?
If I understand what you are asking, it's the same problem as navigating a
ship without a clock.
Classic navigation with a sextant needs a clock and sightings on 3 objects in
the sky
e-nuts] establishing your position w/o gps
have you ever tried to measure an angular distance using a hand held
instrument while standing on the deck of a moving boat in the open
ocean? try it and you will see why they wanted a clock. You
really can't measure an arc minute reliably we s
Then, as now, a knot is a unit of speed, not distance! If you counted 7
knots in a standard song, it was still speed.
-John
==
> On Tue, Jan 24, 2012 at 10:31 AM, J. Forster wrote:
>
>> Nope. A knot is a unit of velocity, not didtance.
>>
>> A "knot" is 1 nautical mile per hour
>>
uts-boun...@febo.com] On
> Behalf Of Chris Albertson
> Sent: Tuesday, January 24, 2012 12:48 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] establishing your position w/o gps
>
> If you want to try your hand at position determination in the pre
On Tue, Jan 24, 2012 at 10:31 AM, J. Forster wrote:
> Nope. A knot is a unit of velocity, not didtance.
>
> A "knot" is 1 nautical mile per hour
> A nautical mile is that distance, subtended at the earth's surface at
> the equator, by 1 arc-minute.
>
> If somebody tells you the ship was going "
position.
Doug
From: Bob Camp
To: 'Discussion of precise time and frequency measurement'
Sent: Tuesday, January 24, 2012 10:13 AM
Subject: Re: [time-nuts] establishing your position w/o gps
Hi
If you spend some time on the auction sites you can find some
[snip]
Then you measure
> distance by tossing a big chunk of lumber overboard with a measured
> rope tied to it. The captains hated doing math by hand so they
> calibrated the rope by tieing knots at intervals so the natural unit
> was one arc minute at the equator and called it a "knot".
Nope.
reason for establishing
> the Royal Observatory.
>
> John WA4WDL
>
> --
> From: "Chris Albertson"
> Sent: Tuesday, January 24, 2012 11:36 AM
>
> To: "Discussion of precise time and frequency measurement"
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] establishing your position w/o gps
If you want to try your hand at position determination in the pre
radio nav days you can buy a "studen sextent" It's a low cost plastic
instrument sells for about $6
hn WA4WDL
--
From: "Chris Albertson"
Sent: Tuesday, January 24, 2012 11:36 AM
To: "Discussion of precise time and frequency measurement"
Subject: Re: [time-nuts] establishing your position w/o gps
On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali wrote:
On Tue, 24 Jan 201
If you want to try your hand at position determination in the pre
radio nav days you can buy a "studen sextent" It's a low cost plastic
instrument sells for about $60. Better ones start at $200 with $500
to $800 for a good one. But it required much pratice and training to
outgrow the plastic in
On Tue, 24 Jan 2012 11:05:58 -0600
"Lee Mushel" wrote:
> If you're looking for a really interesting topic to read about, the
> development of an accurate ship-board clock is really fascinating! And it
> wasn't done overnight!
If you have a few references on books to read, you shouldn't keep
I think James Burke discussed these clocks in one of his documentary
series. Besides not using a pendulum, they were temperature
compensated by using materials with opposite temperature coefficients
of expansion and then gimbaled for use on a rolling and pitching ship.
Oddly enough, the phase loc
inating! And it
> wasn't done overnight!
>
> Lee K9WRU
> - Original Message - From: "Chris Albertson" <
> albertson.ch...@gmail.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com>
> Sent: Tue
and frequency measurement"
Sent: Tuesday, January 24, 2012 10:36 AM
Subject: Re: [time-nuts] establishing your position w/o gps
On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali wrote:
On Tue, 24 Jan 2012 11:04:08 +
"Poul-Henning Kamp" wrote:
In message <20120124115848.
Maybe the Longitude Act was issued also because of the disaster occured in
1707 due to a navigation error: the Royal Navy fleet lost 4 of its 15 ships.
On Tue, Jan 24, 2012 at 5:50 PM, Azelio Boriani wrote:
> Yes, the first real push was the Longitude Act (1714) and the Harrison's
> clocks.
>
>
>
Yes, the first real push was the Longitude Act (1714) and the Harrison's
clocks.
On Tue, Jan 24, 2012 at 5:36 PM, Chris Albertson
wrote:
> On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali wrote:
> > On Tue, 24 Jan 2012 11:04:08 +
> > "Poul-Henning Kamp" wrote:
> >
> >> In message <20120124115
On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali wrote:
> On Tue, 24 Jan 2012 11:04:08 +
> "Poul-Henning Kamp" wrote:
>
>> In message <20120124115848.312d60bd4fccce4f3e71c...@kinali.ch>, Attila
>> Kinali w
>> rites:
>>
>> >All this talk about telling the time using stars or the sun made me won
In message <20120124121642.4a8ad1def54bc32cca928...@kinali.ch>, Attila Kinali w
rites:
>On Tue, 24 Jan 2012 11:04:08 +
>But how do you untangle longitude and time? How do you know that you
>are looking exactly south (or north)?
North/South can be done by timing (widely spaced in inclination)
On Tue, 24 Jan 2012 11:04:08 +
"Poul-Henning Kamp" wrote:
> In message <20120124115848.312d60bd4fccce4f3e71c...@kinali.ch>, Attila Kinali
> w
> rites:
>
> >All this talk about telling the time using stars or the sun made me wonder
> >how did people tell what position their telescopes had ba
In message <20120124115848.312d60bd4fccce4f3e71c...@kinali.ch>, Attila Kinali w
rites:
>All this talk about telling the time using stars or the sun made me wonder
>how did people tell what position their telescopes had back in the days
>before GPS?
Back then the stars were the coordinate system a
Moin,
All this talk about telling the time using stars or the sun made me wonder
how did people tell what position their telescopes had back in the days
before GPS? I know that most countries established a coordinate system
in the last 100-200 years. But astronomy has been around much longer and
h
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