NavList:

Dear Modris,

I did something similar with my SNO-T long ago. But my goal was not to determine the instrument correction, just to practice Lunars and see how accurately I can do them. I made several hundred observations (some of them were posted here) and they are consistent with the certificate that Freiberger made for me, and showing no error more than 0.2'.

The Russian article that you attached to your previous post is from the book of Krasovskii, who was one of the top specialists in the matter in Soviet Union (I have the whole book). He wrote it shortly after the appearance of SNO-T, and explains that the reason for development of this new sextant was the insufficient quality of SNO-M (he discusses the statistics of instrumental errors of SNO-M).

Your results show that careful determination of corrections permit to obtain very good results with a sextant having large instrumental errors. But another interesting question:
How stable is the error curve that you determined? Did you notice any changes in your correction curve with time?

Alex.