Location from star???

Is it possible to find one's GPS position (or just simply
longitude/lattitude) using a camera? (i.e. camera affixed to earth via
tripod, take 3 photos of North Star 24 hours apart, then use rulers and
some simple math/geometry)?

Westcoast Sheri wrote:
Is it possible to find one's GPS position (or just simply
longitude/lattitude) using a camera? (i.e. camera affixed to earth via
tripod, take 3 photos of North Star 24 hours apart, then use rulers and
some simple math/geometry)?


Your question really is can one find one's geodetic location (latitude
and longitude) by means other than GPS receivers, and the answer is, of
course, yes. A sextant and actuate time enables celestial navigation to
approaching roughly 5 seconds of arc (500 feet).

IIRC the US Nave developed a camera viewing the sky to determine latitude
and longitude. Certainly GPS is a much more accurate--and includes the
dissemination of accurate time.

Sam Wormley wrote:
Westcoast Sheri wrote:

Is it possible to find one's GPS position (or just simply
longitude/lattitude) using a camera? (i.e. camera affixed to earth via
tripod, take 3 photos of North Star 24 hours apart, then use rulers and
some simple math/geometry)?


Your question really is can one find one's geodetic location (latitude
and longitude) by means other than GPS receivers, and the answer is, of
course, yes. A sextant and actuate time enables celestial navigation to
approaching roughly 5 seconds of arc (500 feet).

One can determine one's geodetic location with topographic maps to an
accuracy of better than 40 feet, depending on map accuracy and availability.


IIRC the US Nave developed a camera viewing the sky to determine latitude
and longitude. Certainly GPS is a much more accurate--and includes the
dissemination of accurate time.

Sure. It's called celestial navigation. Exactly what did you have in
mind?

Latitude is easy. Longitude, no matter how you do it, requires a time
reference. The easiest way is probably to measure the time of local
noon, convert that to mean time with the equation of time, then turn
the time in to longitude.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte

You also need to know the time in Greenwich.

Mark

laura halliday wrote:
Sure. It's called celestial navigation. Exactly what did you have in
mind?

Latitude is easy. Longitude, no matter how you do it, requires a
time reference ...

Not always. There is a little-used method know as "lunars" that does _mot_
require a knowledge of local time or GMT.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/

This excellent book by Dava Sobel is available in many/most libraries
http://www.stokenewington.net/readin...oks/sobel.html

"Armond Perretta" wrote:

laura halliday wrote:
Sure. It's called celestial navigation. Exactly what did you have in
mind?

Latitude is easy. Longitude, no matter how you do it, requires a
time reference ...

Not always. There is a little-used method know as "lunars" that does _mot_
require a knowledge of local time or GMT.

But there is an implicit time reference in the lunars method in the
form of an ephemeris. The method works by using the Moon's position
to determine the time.

David Brodeur

In other words:

Short answer: no.

Long answer: that depends...

Since the original poster has never returned, one must assume they
weren't all that interested anyway.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte

That never stopped anyone on SAA before...

laura halliday wrote:

Since the original poster has never returned, one must assume they
weren't all that interested anyway.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte