NavList:

Marty Lyons,

Rather than worrying about seeing miniscus lines and fluid coloring from a long way off, walk down there to the far reservoir and stick a nice visible piece of bright yellow (or other high-contrast color) tape on the reservoir aligned carefully with the meniscus, or, maybe better, mark the line on a stake driven into the ground next to it. Do the same at the near end. You should be able to mark the two levels within a quarter of an inch, and of course they are reliably and accurately level to less than that after any short-term oscillations settle out.  Once you have those two visible markers, drain the fluid! You're done with it. Then move some considerable distance down the line from either end. You can then sight to the two markers (a low-power scope may help), and that's your level to considerable accuracy. Maybe drive another stake into the ground there.

Anyone have an ocean view from a hilltop? Given a leveled line, sight along it to the sea horizon. It's not aligned with the level line. You have a visible demo of the dip of the horizon. 

You wrote:
"Attached is the data from shots taken today.  Results seem pretty far off from the Anti Spoof numbers. Not sure why. I believe my technique improved as the sights progressed."

Yeah, it sure looks that way! After 21:00, the average of your sight errors is less than a minute of arc, with or without the outlier. That's excellent. Of course the individual sights show a lot of variability, so it's good average accuracy but with a fairly substantial standard deviation of around 4 to 7 minutes of arc, depending on inclusion of the outlier. That sounds very reasonable and suggest you have nailed the index error quite well.

This is all very nice, but of course you're left with that puzzler: what the heck was going on with those earlier sights with much larger errors? Any ideas?? Can you try some Venus sights in evening twilight in the next few days?

Frank Reed