Atlas EQ-G Strange Behavior
Posted 08 February 2013 - 12:12 AM
Tonight as I had used the scope and mount two nights previous and had not moved it, after a polar align check I shot a one-star alignment on Sirius with no problem. On my second Go-To, the scope did not line up on the target, so I returned to Sirius where I got a good alignment. I walked it out star-by-star, but by Rigel it had a good 2 degree error.
I then parked the scope, shut it down, rechecked polar alignment, and attempted to align again. My first alignment star was Sirius, but the scope was pointed in the vicinity of Alnitak. Every attempt to align after that resulted in about a 25 degree error. I shut down the mount and very carefully re-entered all time, date, and location data several times and then tried to align. The 25 degree (+/-) error persisted no matter what I tried. I aligned on Polaris three times, checked every setting, and carefully observed for wire-binding, but found no errors.
Any suggestions would be greatly appreciated.
Posted 08 February 2013 - 12:22 AM
Posted 08 February 2013 - 05:33 AM
Posted 08 February 2013 - 08:51 AM
For several of the stars the scope clearly was pointing at where they would be in an hour or so, but when I tried to use Regulus as the first alignment star, while it was up about 40 degrees on the
meridian, the scope pointed approximately at the horizon, or where Regulus had been over an hour before.
After the initial quite normal one-star alignment where the scope hit Sirius pretty much dead center without adjustment, as I mentioned above, I noted about a 2 degree error in about a 30 degree move. I initially thought I might a have wire bind, but when I input Sirius, moving from the 2 degree error, the scope stopped dead-on centered on that star. AS I noted, this has got to be among the top-ten weirdnesses I have ever encountered.
I actually encountered a similar set of issues long ago when I inadvertently had unbalanced the scope by adding the Teleview 2x. After moving the focus tube out to accommodate, a combination of the out of balance condition and a less than perfectly tightened slip lock resulted in a serious misalignment. But, that problem revealed itself when I moved the mount to a parked position in that the scope was still misaligned at park. In this set of events, the scope parks perfectly.
Posted 08 February 2013 - 09:04 AM
Posted 08 February 2013 - 09:17 AM
Posted 08 February 2013 - 01:38 PM
Posted 08 February 2013 - 02:31 PM
One thing I noticed on our local club's CGEM was that mount was NOT keeping date of last use. For sometime I had to make sure the exact date and time were entered.
Posted 09 February 2013 - 12:12 AM
Tonight I fired up the mount and had the same results as last night, but tonight I just cranked up the rate and aimed it at Sirius anyway. After fine tuning, the paddle claimed that the alignment was acceptable, even though I had motored across about 25 degrees of sky. From there the go-to worked perfectly.
Clouds moved in early, so I parked the scope. The parked position was visually out of line with the tripod leg (which I had used as my guide last night.) Careful examination determined that the lateral adjustment knobs for polar alignment are nearly at their limits, so the weights were well out of line with the north-facing leg of the tripod. My error last night was that I was aligning the weight shaft with the north leg of the tripod, as I normally do.
Embarrassing but very real. Thanks guys for the attempted aid. I got some pretty good exposures of Lower's Nebula tonight.
Posted 09 February 2013 - 04:35 AM