If you recall I posted a message a week or so ago about goto accuracy problems
with my 8" LX200. Initially I getting about 1-2 degrees of goto accuracy. I
made some minor tweaks to the OTA alignment and was able to get that error down
to about 30 arc-min for large slews. However, I just realized tonight that if
I decrease the maximum slew speed from "8" down to "5" then my pointing errors
decrease to around 5 arc-min for medium slews (< 90 degrees) and around 5-15
arc-min for large slews. Has anyone else experienced this increase in accuracy
at slower slew speeds? It makes sense that this would increase accuracy but
I've never seen this mentioned anywhere. The pointing error that I get at high
slew speeds is almost entirely in RA and almost none exists in DEC. Also the
error is always because the RA drive overshoots the target coming from either
direction. I can live with a max slew speed of 5 but it would be nice to get
the same accuracy at the slew speed of 8. The accuracy seems to get even
better at slew speeds below "5" but anything below 4 or 5 really gets slow for
long slews. However, I can handle the extra time for slewing if it actually
hits the target. Are there any tweaks that can be made to the RA drive to
improve this?

If anyone wishes to try this to improve accuracy just keep in mind that it
always defaults back to a slew speed of 8 at power up (6 for 12"). Also make
sure you make the speed change BEFORE you do the 2 star alignment because it
makes a big difference.

I'm just so excited to be able to finally GOTO and have the object in the
eyepiece!

John

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