Sorry for continuing to beat a dead horse, but I'm going to keep on beating it until I wrap my brain around what's going on with my instrument.
My recent Solar endeavor revealed that on at least one session, I had not adjusted the Vertical 0 datum, so I did that before my next session.
I also went through the procedure outlined in the manual to adjust for the Systematic Error of the Instrument.
I set up in the shop about 20' from a wall with a plumb bob suspended on a fine thread (.007" diam.). My initial plan was to sight the thread at or near horizontal, then raise the scope up to 30 degrees, and see if it was on the thread without horizontal adjustment.
After leveling the instrument carefully with the vial, I zeroed the horizontal angle. Then I noticed that just by raising the scope, the horizontal angle changed! It was indeed still on the string, without touching the horizontal screw. Here are the numbers:
Direct:
Up: 359-59-21
Level: 00-00-00
Down: 00-00-17
Reverse:
Up: 180-00-36
Level: 179-59-59
Down: 179-59-21
The constants after the adjustment from some days ago were:
VCo (The "Error of vertical axis (X, Y tilt sensor offset)"): -00-23-24
HCo (Collimation error):-00-00-09, and
Hax (Error of the horizontal axis): -00-00-38
Is what I'm seeing, just the compensation at work?
Now you know why I prefer 100% mechsnical optical analog. And your big D/R split on high vertical angles.
I tried to search and find your original post with no result so I must ask
What instrument are you using?
See, D/R split.
Notice that the 2 horizontal "up" angles average to:
Up D 359-59-21
Up R 180-00-36 ( subtracting 180-00-00)
__________
Average H 359-59-58.5
Level D 000-00-00
Level R 179-59-59 (add 180-00-00)
_____________
Average H 359-59-59.5
Diff: 000-00-01 Not bad. And very much the same as seen in your solar az angles. and 30" at 20 ft is 0.03 inches. Hard to see.
Note up H angles are 36" and 39" from 360å¡ (Average 37.5") and Hax err reported -38"
Coincidence? I think not
A Harris, post: 368893, member: 81 wrote: I tried to search and find your original post with no result so I must ask
What instrument are you using?
Topcon GTS-255
Downs
000-00-17
179-59-21 (add 180å¡)
___________
359-59-49
Not expected. But the 179-59-21 is 39", Hax?
It appears that with this instrument Topcon has added a feature that compensates for instrument not being set up perfectly.
It would appear that you need to set it up on a stable pillar to have any real chance to take out small errors that weak tripods allow.
My Sokkia unit will perform and produce excellent closures.
When there is a need for extreme accuracy, there are two routines to go thru after setting up and leveling instrument, 1 index the leveling and 2 index the culmination. The routines will have you ready to do the absolute best the gun will do.
When the initial error of culmination between direct and indirect observation approaches 1min, the more difficult it is to index the culmination by electronic means and at reaching 1.5min of error it is beyond the limit of the electronic compensation to make any culmination correction.
This should be somewhat of a standard in the industry and that Topcon and Sokkia are now a part of the same company.
Your unit gives a 38sec value of error in the vertical culmination in your limited 30å¡ up and down observation and that is enough to hinder your efforts for solar observations.
Just imagine what it would be at the full range of the scale of direct and indirect observation on the same target.
I would suggest it to take another visit to your Topcon guru and his optical alignment apparatus and for you to become one with your technical manual and instrument.
good luck
A Harris:
Does the averaging of D/R split, in this test, not confirm reasonable 1" performance H angle? (Which appears to be trunnion axis leveling error.)
I also cite his solar az on 2 successive occasions, returning 5" repeatability, at 33å¡ VA both times, with 30" D/R splits both times. And in agreement with the arithmetic above.
The instrument may perform constant horizontal sightings with near constant results as expected and still have vertical error.
Any errors in culmination or vertical axis appear when sighting or attempting to align points that fall on different elevations.
Having 1min of vertical error would not create 1min of horizontal error.
If the readout on the instrument does not match the raw data, then it should all be a digital correction factor.
I would prefer that they match and all the wizardry stay behind the curtain.
Some how a digital compensated TS doesn't sound better than a manual index, long vial T2.
Larry Scott, post: 368922, member: 8766 wrote: A Harris:
Does the averaging of D/R split, in this test, not confirm reasonable 1" performance H angle? (Which appears to be trunnion axis leveling error.)I also cite his solar az on 2 successive occasions, returning 5" repeatability, at 33å¡ VA both times, with 30" D/R splits both times. And in agreement with the arithmetic above.
Hold the phone, guys. This wasn't a carefully devised test. I never got to that. The gun was only turned up and down quickly and I'm not sure how far in each direction (although I did take photos and could look), and I noticed the horizontal numbers moving. That's when I stopped. I'm trying to understand what the instrument (and these corrections) are doing.
Some time ago I think I actually posted a sketch labeling the axes, but I can't find it now.
I'll do this again sometime really carefully, but plot the H vs the V, before further adjustment and see what it looks like.
In the meantime, I will do the VDatum =0, before more Astro (tomorrow am), because that's super easy to do.
