NavList:

Dear Lance,

Thanks for your reply which clarifies a number of points.

Hence, the source you used for both Hs and Hc is Software.based.

From your data :

- The Software which supplies you with Hc values is accurate to better than 0.1'.

- The Software which supplies you with Hs values seems to be much less accurate than 0.1' for the Moon, here it is about +/-0.5', a Software performance which, if confirmed, may need improvement.

As regards the theodolite I am using now and then, that's a rather old one - built in the 1960's - i.e. shortly before the introduction of electronics. Good sturdy mechanical and optical pieces especially designed for Celestial Observations - hence with a superior and very reliable - so far - heights measuring system.

A good Friend of mine installed a firm basement / support for it directly over the rocks just nearby. I never use it by windy or rainy weather and never directly at Sunlight. The levelling also takes some time, and is mainly based on various bubble settings with subsequent aiming at known points nearby within 2 NM as benchmarks.

I have installed a Time registering system accurate to +:- 0.1s of UT1. I generally take 5 observations in a row and average them. Through about 1,000 Sun observations over a 6 month period, I have been able to pinpoint my theodolite position to +/- 30 m, i.e. within 1" .

No problem therefore to obtain "intercepts" consistently better than 6" with a few series of 5 observations in a row, generally spanning over less than 3 minutes of time.

Kermit