This is a pretty neat exercise for the newer users, builds a bit of confidence in using the Locus system.
Set a couple points and observe the azimuth on a sunny day with a solar observation. Then set up a pair of Locus receivers and process the data. Just seed the processing with the "nav" position, solve in geodetic with Lat and Lon.
Then down load the program "Inverse" from the NGS website. Input your points in Lat/Lon and check it against the solar observation.

Dave,

We just inverse the SPC's and apply the theta supplied from the processor. Still amazing to see the solar obs. compare so close. I accidentally hit a line at 00°00'02" one day. Guess I should have considered the LaPlace correction and cleaned it up. lol

J.D.

Having done sunshots for the past 16 years and now having the locus we have been checking into prior jobs and are always hitting within 20" I love it..

Steve

I shoot very careful solars, and check the locus within 5 seconds every time.

But that is after the laplace correction.

If you live in a mountainous area, know that your laplace correction can be up to 30 seconds arc. The Laplace correction is available on the NGS website for your area, and for most sites is less than 3".

This is one of the magical benefits of GPS, that you have a good basis of bearings even without a tie to published control.

Seism

I'm sure if I would occupy the same points from the sunshot I would do "better than 20 sec" but normally I check into a couple of pins from a previously adjusted job

Steve

I know I shouldnt get better than 10 to 15 seconds on solars, but there is something about me and solars, I always have checked within 5 seconds on a solar from a previous solar, GPS, or other dependable control. Go figure.

Thats with Std Deviation over 3 reverse 3 direct under 5 sec. Maybe my math fools me a little, but it never fails.

By the way watch for "drift" in a solar solution. After having shot several hundred solars over the years, I look for a steadily increasing or decreasing azimuth result as the best indicator of a blunder in method or computation.

A note for you astronomy buffs out there.

I stopped fooling with Ephemeris tables a few years ago and use an astronomy program called "Redshift" to get positions for Sun & polaris (and any other daylight planet or nightime star as well). I keep checking the results against the ephemerides to within expectable margin of error (a lot better actually).

Should be good for several more years, if we dont get an unexpected gravitational body jerking things around.

Anybody else using this software?

Seism

I would like info on this software.

J.D.

Info is available at www.hyperdrive.com/redshift2

This software provides declination and right ascension (also altitude), which can make it difficult to use if you are accustomed to using Greenwich hour angles, as are supplied by Sokkia handbooks. You can convert.

The cost is $10, so what the heck.

Seism

I always did 4 direct and 4 reverse
and like you say .. all done in less than 5 minutes. I bought a AstroRom for the 41 years ago and hve used that since.. but
I have not done one sunshot since my purchase of the locus system.... I use to put them on every job.. times are changing