Hi Everyone, For those of you have never done this,you do not know what you are missing. I think every surveyor needs to do this ,if it is just for the fun or experience of doing it,a lot of old Deeds, even today have yesterday bearings,magnetic bearings or Declinations where once used not to long ago, a surveyor should be on guard, when taking Bearing from plats or old Deeds, Astronomic azimuth were and are used in some cases for Geodetic surveys on today's Monuments.A direction determined from Sun or Star observations results in an astronomic azimuth which usually differs slightly from geodetic azimuth. Simply stated, astronomic azimuth is base on the direction of the vertical and axis of rotation of the Earth. Geodetic azimuth is based on a mathematical approximation of the Earth shape The term Azimuth is define as a clockwise angle from astronomic North.This method at one time was widely use to help improve the line of Directions that were being recorded on modern surveys. Modern surveyor no longer used magnetic bearings that had Declinations applied for their surveys, so before GPS this was the only way to determine North.and be more accurate than a Compass of yesterday surveys. In fact they are real accurate to say a lease.To do this you had to plan it all out. Lat. and Long had to be known and you had to have a real accurate time piece. The HP 41 CX has one of the most accurate clocks that is made in a calculator even today. I may have used it more than any other to do this. That includes the HP 48 GX and TDS Recon.But this is something to experience , if you have never done it. Looking at the Sun move (the Sun does not move) puts you in prospective with how fast we are moving thru space and more how fast we are turning. But this all had to be planed. If you had a filter you could take a Sun Shot, If not a Star Shot, but this means it had to be done at night.( Many Thanks to Ron Dry,Polaris shots Day Time) This was even more work to prepare for it, Both has to be done at certain times of the day or night.Your angle on the horizon can be to less and also to great, There are no midday Shots and the same for looking at Polaris , Also Clouds could stop you from taking one, also the Seasons ,in Winter you have less time in the day more at night . You have to take 6 sightings as fast as you can do them, This may seem hard but you get good at doing it. But your work for property had to include it,to be completed. Cell Towers when they came in all had to have this done for their alignment to North. GPS.replaced this method, but it is still required in some surveying. Like i mention you can find geodetic monuments that includes astronomic azimuth in their Data, When you look at them notice the different in this Azimuth and the Geodetic Azimuth. So i will give you 2 links to download a Sokkia Celestrial Observation Hand Book on Ephemeris, this download is for educational purposes only from the three Authors who are all Professors, this book has programs for HP 41CX,HP 42s and the HP 48GX,
Later in replys i will feature the 41cx and 48gx programs with instructions and go over the notes. This was also one of the last books i used, You had to have this book to do it Plus knowing how to set your clock that you were using, then you would need a stopwatch with it or the calculators clocks, I have a large stack of these books, one for every year. So see how the Hour Angle Method HAM, was done.
Below i have attached two txt. files ,one is the 48 program and the other is the instructions to it.
"Thanks to Ron Dry for his input on Polaris During the Day"