Collimation for fun
Much more time has gone into the Torus telescope project this summer.
The latest results from last night show a good night coarse collimation. The plan was daytime coarse, nighttime coarse, nighttime fine collimation runs.
Daytime coarse collimation was done attempted many times until we thought it was a good as it was going to get.
The next step was a night time star collimation.
The scope was pointed up on its end (to eliminate the push bolts from the equation), at Altair, defoccused to fill 1/2 the field of view and imaged with the ASI120MC camera with 0.5x focal reducer.
The Vtruss hangers were loosened, the push bolts loosened and this first image was taken, as a starting point.
The end goal is to get the dark centre centered and symmetrical. Here you can see it over near the 9 oclock position.
Very tiny (1/6 turn) adjustments were made on one pull bolt at a time and recorded and imaged. In the end, as good as I could tell visually, the end result was one pull bolt 2/6 turn counter and another pull bolt 3/6 turn clockwise from the daytime coarse collimation (I recorded the session in audio and have to transcribe the notes to be sure those are the final adjustments).
Where it looked pretty much centred by eye. But possibly still not good enough.
After that, the push bolts were moved into contact and then tightened 1/4 turn each in turn. The image did wander a bit and lost some of its centering. Then the Vtruss bolts were tightened hard. The image did wander again but came back to its starting point when done.
The next attempt we will overlay a transparency target and try to actually measure as we go. Looking at this some more, it now appears to me to be a little to the 7:30 oclock position.
The air currents were tremendous, and it appears to have some dust in the optical system, most likely the camera. It will be cleaned later today.
The scope was outside before sunset and given 40 minutes to cool down. There was some dew as well and I wonder about heating the secondary mirror… it looked a little foggy at times. Even this little amount of tweaking to the collimation broke the pointing again and that will have to be redone in the end.
Another dead mouse to add to the tally. We now have 4 traps on the pier.. a little hazardous to the astronomer as well!
Lastly, I shot an imaging run of Mars… at 2 or 3 ms per image! but at an equivalent of f5, Mars was little more than a bright red star with no surface features.
The nights are good.. warm low temps means the telescope does not have as far to cool to ambient. No mosquitos for the first time in months is also very good. However the moths are out in force, flying towards all of the lights inside the observatory 🙁