6 years in the game need help!

[Explorer 190 MN]

I am lost this time. I have elongated stars in RA.. the witch hunt begins... Guide stas with OAG are also elongated but the Howie Glatter laser tells me everything is fine, The telescope drive master encoder tells me RA PE is within 1 arc second peak to peak. The guide graph (Maxim) tells me sub arc second guide error with 5 second intergration times but elongated stars. Pempro tells me over a 20 min period the average RA drift is 0.2 arc seconds out to the east. Balance weight accordingly. Cable trail is minimal tuned using the read out from the telescope drive master. It has a resolution of a 1/8 of a arcsecond at 5 Hz all mounted in a Obs no wind.
 

[Explorer 190 MN]

[Explorer 190 MN]

My signature is wrong dont know how to change it I have taken the AO off

 

[Owmuchonomy]

If you are positive it is in RA then it could be mount backlash.  Whats the focal length?

[ollypenrice]

Firstly, can we eliminate the optics? A short test sub on a nice bright starfield would not give the guiding a chance to cause the problem so if the stellar deformities were still there then it would be the optics. That's an easy test.

The deformation just might have the signature look of backlash in so far as one can tell, though that is not very far. (The larger stars look like two overlapping ones, a smaller one at the top and a larger one at the bottom, both round. This is often what we see in backlash when the mount spends most of its time either on one side or the other of free play. It spends longer on the lower 'big star' side here.

I'm wondering if a 5 second guide interval might be enough to see an oscillation across the free play and back without it having a chance to show up on the trace. Bit of a long shot and thinking aloud because you'd expect some guide hits to be made on the other side of play and show on the trace. But to continue the line of thought, suppose the mount naturally rested on one side of play and the guide pulse sent it to the other, then it might fall back to the rest side within the five seconds and do this consistently. Just a thought.

It couldn't be tilt? I know these RCs have tilt adjustment and I guess you've sorted that with the Glatter? The short test sub would show this up.

Olly

[Daniel-K]

Which howie glatter are you using?

Although mine  was saying its right i still had to tweak mine while using a live image.

Do you have the tilt plate?