Monthly Archives: January 2011


The newly fabricated dome friction drive wheel didn’t work well, perhaps due to the -20C temperature. The motor control circuitry kept blowing the 10 amp fuse. Even the hand crank couldn’t move the dome properly.



  1. Began mapping the dome for areas of possible interference between the Newtonian mirror and obstructions in the dome, but stopped due to time constraints.
  2. Checked the Cassegrain focal plane position and found it to be too far out; the eyepieces needed to be retracted 1 or more cm from the focuser tube and even then, the best focus was near the outer end of travel. Moved the convex secondary out a couple of millimetres and the best focus now seems to be near the midpoint of the focuser travel.
  3. Checked the collimation of the convex secondary with my laser collimator and it was good.
  4. Checked the collimation of the main mirror by looking at a bright star and found (by the out-of-focus test) that it was off. The back nuts were adjusted to make the image true.
  5. Checked the slewing, both in RA and Dec. The scope ‘gallops’ a bit in Dec (downward) — we’ll adjust the balance when we can.
  6. Aligned all the finder scopes.
  7. Repeatedly moved the flip secondary mirror Cass-Newt-Cass. The star remained within the centre 1/3 of the field.
  8. Got my ST-9XE CCD camera working on the dome computer and took images using the bottom port of the four shooter. (This was without the telecompressor lens.)
  9. Analysis of the acquired CCD data showed an fwhm (full-width at half maximum) of 4.43″, a reasonable figure considering how unsteady the atmosphere was at the time, and comparable with data captured in 1999, 2000, and 2001.

Bob, Gil, Glen