Going good before going downhill!

[Fay]

I set up late but everything went well, M51 in sights, perfect sky only problem was, every image drifted, guiding was completely off. Never had it before. It got to 11pm & I looked into everything to correct it, to no avail. I was doing 300 secs exposures & could see that the guide star was moving slightly off the centre all the time. My GPUSB, has a red light, which I am  sure goes to green when making a correction. I am sure that apart from when it was turned on, the green light never came on, although corrections were being made.

I looked  at one of the images & M51 had drifted up to the top of the frame & yet the guide star was still in the same place, strange, I thought , am I on a hot pixel? When I moved the mount the star did move.
Checked for sticky keys on handset. 

I was trying to think what I did different, to when I went out about 2 months ago!!!!

PHD 1.8 used to have 1.6
I aligned on two stars in Ursa Major, never done that before, always have a big distance between alignment stars.
Had message when PHD calibrating " star not moving enough" was this because of the above, everything happening near the pole & in the same area?
PHD started doing backlash corrections, when calibrating - never had that before.


Help!

[JohnP]

So did it finish the calibration OK or not...? What guide camera was you using...? Sounds like your polar alignment was way off if m51 was moving across whole frame in a 300secs sub unless PHD was forcing it to move...

John

[Fay]

Yes it finished the calibration after about 4 tries. I was using DMK, forgot to mention that, my polar alignment looked ok I rechecked it. Could the camera affect it?

[Mike]

I had exactly the same issues one night. Spent a frustrating hour trying to figure out what was wrong with my settings, re-polar aligning, etc. before I suddenly realised I had forgotten to connect the guide cable fromt eh camera to the mount. DOH!!! 

[Fay]

I know what you mean, Mike, half the time it is something silly, but it was connected. 

[JohnP]

Fay - I would suggest going back to what you know works as a starting point. Have you got your LX webcam back - if so try that & just make sure all works & then switch to using DMK... at least this way you can eliminate your GPUSB box & PHD. If you have issues with the DMK it must be to do with the way it is setup etc. in S/W.

Thks, John.

[Fay]

John, yes, that was in my plan, to switch camera's. Perhaps I have something that should be setup in the DMK folder. I will have a go tonight, if it is ok.

What program does Chris guide with?

[JohnP]

I think he still uses K3 - but he doesn't use the DMK for guiding (I don't think) - I think he uses his QHY5 or whatever it is called....? I might be wrong though.

John

[Fay]

John, regarding Chris's UBA post, he used the dmk for guiding. I have sent a post to the Stark yahoo group forum, to ask if I may need a special plug-in for the DMK, just in case, probably not.

[Fay]

Could be an answer. Just noticed that my RA agressiveness was on zero. Default is 100!!
I think yours is 100 John?

[JohnP]

correct - Aggressiveness 100 - Hysteresis 10... Looks like you have found the problem....

[Fay]

Don't know how that got changed I have never looked at it, just left it on default. Must always wear glasses!!!!!!

[Mike]

Yep. If it's on zero then there will be no movement on that axis. Problem solved !!

[Fay]

Well, that was the proble. All is now well, thank God, did M51 last night, not that good as I only had time to get 9x300secs. I am just glad that guiding was ok & the mount isn't toasted!!!!!!!!!!!!!!!!

Will post when it's ready but don't expect too much. Grateful for small mercy's at the moment