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.  Each sighting  gives you a circle on the globe, or a line if you
know roughly where you are.  The lines form a triangle.  The size of the
triangle is an indication of the accuracy.  You pick the objects so the
triangle is roughly equilateral.
http://en.wikipedia.org/wiki/Celestial_navigation
You can get time from the moon, so in theory at least, that's an answer to
your question.
http://en.wikipedia.org/wiki/Lunar_distance_%28navigation%29

Years ago, when a friend was learning navigation, he was reading one of the
old classic texts.  There was a good story about the guy off the coast of
England/Ireland who didn't trust his clock, so he did the calculations again
assuming his clock was a bit fast and again with it slow.  That gave him 3
parallel lines for each sighting.  Anybody recognize that story?

Longitude by Dava Sobel is a good read, especially for time-nuts.  There is
also a version with lots of good photographs.

One of the techniques they actually considered before Harrison built good
enough clocks was to derive time from Jupiter's moons.  They knew enough to
correct for the time shift due to speed of light delays as the Earth-Jupiter
distance changed.  (I don't know if they knew if was due to speed of light.)

You can synchronize two clocks if both sites can see the same event in the
sky,  Occultations are often used for this.

With modern technology, radio telescopes are very very good at this.  In
order to do VLBI, you need to know where the telescopes are located.  With a
big collection of data you can do least-squared fit type calculations to
refine the location and clock calibration.

--
These are my opinions, not necessarily my employer's.  I hate spam.

Is the USNO almana/ephemeris still published in hard copy every year? That
had moon timing, etc.

-John

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-John

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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
reaches the lowest elevation when crossing the observer's local meridian,
but reaches its highest elevation twelve sidereal hours later.

John  WA4WDL

On 1/24/12 3:19 PM, J. Forster wrote:

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 sources.  You could also download the pdf (but printing it
would cost you more than the $20)..

Amazon has it, for instance.

http://www.usno.navy.mil/USNO/astronomical-applications/publications/naut-almanac

will find it, but the GPO version is more expensive than the commercial
versions..

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 photograph these stars draw circles around the pole, the
centre of the circle
is the celestial pole and its elevation above the horizon gives the
latitude.
You can also use an almanac and a calendar to determine your latitude
by observing stars
with the theodolite.
You observe the sun at noon to find the local time and set your local
clock. You then
wait for an event like an eclipse of a planets moons to establish the
relationship
between your local time and the time at a known site.
A theodolite has a telescope that can be "plunged" i.e. used upside
down and this
technique is used to get a very accurate level from a striding level.
No pool of mercury
is needed.
The setting up of a theodolite uses sitings  and reversed sitings to
set the vertical level.
The main error is the atmospheric refraction which scatters
individual observations,
so many repeated observations are needed. The local time observations
need to be
repeated for good accuracy.
A sextant is a less accurate instrument that has the main redeeming
feature that when
reading it you superimpose the image of a star or the sun with the
image of the horizon.
Although the image seen may be rolling around, the position of the
sun on the horizon
is rock steady and is adjusted by the thimble for coincidence. The
elevation is then
read off the vernier. A theodolite needs a solid base to work from
and would be useless
on a ship.
cheers,
Neville Michie

On 25/01/2012, at 12:52 PM, Jim Lux wrote:

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.

Not quite so straight forward. You have to have accurate siderial time and
an almanac. Polaris is only near the pole, not at it.

Not so easy. At the celestial equator the stars are moving in Hour Angle
at 15 arc-seconds per second.

-John

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On 26/01/2012, at 2:49 AM, J. Forster wrote:

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 the best measurement from an analogue instrument.

No need for time, you follow the azimuth of the star until it turns
around and then again until it turns back. Half the difference gives you
the azimuth of the pole very accurately. Fit your observations to a
parabola to get a good result.
Works best in Winter when the sun is down for more than 12 hours. A
good technique as refraction errors cancel.

As I said, analogue measurements need some skill and perseverance.
If you added more modern technology you could track your theodolite/
telescope with a clock so you would get a longer period to adjust/
observe
the observations and set your clock.

Neville

Assuming youcan do that w/o bias.

A T-2 ius a 1 ard second instrument, a T-3 is 0.1 arc-second. I've never
seen a T-4 in the flesh.

That means observations over more than 18 hours. It'll take you most of a
year, unless you are above the artic circle.

See above.

In practice, the "seeing" is nowhere near 1 arc-second for 2-3" aperture
'scopes.

And to do that you need a sub-arc second telescope mount. You just can't
mount a camera on a tripod.

That's an understatement. I've done it, both for North lines and to adjust
a 24" telescope.

The "modern technology" just makes the angle readout direct.

-John

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