A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2020 Apr 15, 09:15 -0700
I use the older Soviet-era СНО-М which I inspect for perpendicularity/side/index error(s) before every session. It is indeed in good condition, I rarely have to touch those settings. If the IE is in the ±0,2' range - I do not zero it out completely. Very rarely I find it (the IE) just outside that range. I never proceed to taking sights before I do the IE measurement with the Sun's width and the readings also give the correct value for the Sun's SD (taken from the NA).
The Venus-Sun session we discuss was made with the 7x Keplerian scope. I doubt I could reach that level of accuracy of the sights with a 3x Galilean scope, more so - with a peep-hole (0x scope) accessory. With the latter - I'd never saw Venus in the daylight.
Regarding the raw data: I thought it would be completely impolite to publish that. I though it would require anyone potentially interested to apply the watch error correction, etc. Besides, just recently we had a topic of the Error vs Correction, and I'm not sure we (the list members) have all agreed on that. As of me - I use a formula which returns a signed value I always (algebraically) add to HS's. So, this must be a "correction" but in my logs I write it under the "IE" name, this will definitely confuse someone. Probably I should just change my habit. By the way, if my watch was fast by 40 seconds, what is the supposed way to mention that? I write that the "WE" (the Watch Error) is "-0h00m40s", the negative value - the same as with the index error.
Did you get my privately-sent e-mail?