Can I get my position coordinate (B,L) using astronomical survey by ( stares positions survey )?

Question

What I mean is can I get my position cordinate (B,L) using astronomical survey by ( stares postions survey ) instate of using GPS. my friend said :" yes we can... and we will get better result and it is more accurate than GPS...!!!"

Is that true..?!!

If it is true how can we do it,? what inestrument can use to do that.

I hope I am clear.

Answer 1

you can indeed determine your latitude and longitude by observing stars (until recently this was the only option travelers had), but your friend needs to smoke better quality crack if he thinks he can do better than gps.

one simple example: you can determine your longitude by determining the time of local noon, correcting the apparent time to mean time (using the equation of time), then measuring 15 degrees of longitude per hour east or west of greenwich.

i tried this and got a longitude that was within 10 minutes of where i really was (equipment: clock, stick in the ground, planisphere). gps can do better than that.

do a search for "celestial navigation".

Answer 2

A theodolite. Every geodetic surveyor is taught this and how to do it at college as part of the course.

Ancient mariners used a device called a Sextant.

Not sure what you mean by B,L that's not clear.

Answer 3

GPS is generally accurate to about 10 meters or so, for a few minutes of integration (assuming you have a clear view of the sky).

To get more accuracy than that with astronomical survey, you are going to need telescope accuracy of better than 0.5 arc-seconds.   That will require a 25 cm aperture (10 inch) -- a bit on the large (expensive $500) size for amateurs.  Plus a theodolite and some precision clocks.  But I don't know how to find the local vertical / level to that accuracy, without a $1000+ instrument.

Professionals can do surveys to better than 2 cm accuracy, without GPS or LORAN.  But they have lots of special equipment, and even then it takes days or weeks of star sights.