NavList:

Hello, Alex!

I am really glad to hear from you.

I remember your posts about certification of your own SNO-T very well. And I remember your regular posts about the adventures with your SNO-T. Experience you shared with others was very useful. I read your posts with great interest.

Yes, I agree that Star/Star distances are more problematic then the Sun lunars. Some possible reasons:

1) the images of the stars in the field of view sometimes are dissorted by atmosphere (especially for bright stars). In this case it is impossible to estimate presise contact to the level of 0,1’. In these cases you can rotate the micrometer but visually you don't see any changes in the position of the stars;

2) large brightness contrast between the two stars of different brightness may be one of the factors that makes  accurat contact difficult;

3) The contact between the two stars in the field of view has to be adjusted precisely (contrary while taking lunars we can adjust the contact only roughly and then simply wait for the contact moment);

4) If inverting scope is used at very dark night (without light pollution), it is not possible to see ocular wires as well as the edge of the field of view,  as a result it is much harder to control contact in the center of field of view thus introducing offset errors (this is important for large angles). 

5) Uncomfortable sextant position that makes accurat adjustments of micrometer difficult.

And I definitely support your oppinion that Sun lunars are the best.

Modris