Polar alignment issues

[hornedreaper33]

Hey all, finally had a clear night after two weeks of rain. Set up as per usual and excited to start using my Optolong L-Pro!

Lined up AVX with polar alignment scope. Ran two star alignment (Vega and Altair) and added two calibration stars (Mirphak and Mirach). I did all star polar alignment on Capella and noticed the mount wanted to move a little further than I would have imagined.

Long story short, I was aiming for 180 seconds on M33 and had no chance. Can anyone suggest any tips please?

As I mentioned, we have had a lot of rain and I thought maybe the mount was moving in the damp ground however, it was on three approx 10" square pads that should have mitigated any movement.

Thanks

[PeterCPC]

I don't quite follow. You say that you used a PA scope but then that you did ASPA on Capella. Now, I use another method but I used to use ASPA and never used a polar alignment scope. ASPA cannot just be used on one star so I am either misunderstanding or you have not done ASPA correctly.

Peter

[hornedreaper33]

Hey @PeterCPC, thanks for the reply. I'm just following instructions on the hand controller, sync with a star then the mount slews to where the star would be if your PA was correct and you bring it back to centre with Alt-Az adjustment. Hey presto. 

I've had this be pretty good in the past but the only thing I can think I was doing differently is how I moved to the first go-to alignment star. I usually disengage the RA and Dec clutches and move manually to centre the star in the finder. Engage the clutches and centre on screen with the hand controller. This time I did it all using the hand controller however, this would only affect go-to accuracy right??

Confused. We have a very good night coming up tonight and I hope I can get my PA dialled this time. I would like to use the polar alignment feature on sharp cap but I think my focal length is undesirable for that.

Edited November 20, 2019 by hornedreaper33

[Thalestris24]

8 hours ago, hornedreaper33 said:

Hey @PeterCPC, thanks for the reply. I'm just following instructions on the hand controller, sync with a star then the mount slews to where the star would be if your PA was correct and you bring it back to centre with Alt-Az adjustment. Hey presto. 

I've had this be pretty good in the past but the only thing I can think I was doing differently is how I moved to the first go-to alignment star. I usually disengage the RA and Dec clutches and move manually to centre the star in the finder. Engage the clutches and centre on screen with the hand controller. This time I did it all using the hand controller however, this would only affect go-to accuracy right??

Confused. We have a very good night coming up tonight and I hope I can get my PA dialled this time. I would like to use the polar alignment feature on sharp cap but I think my focal length is undesirable for that.

Hi

See p29/30 of the manual. To polar align using ASPA you have to align on 2 stars plus a third calibration star before selecting another star to do the mechanical alt/az pa adjustments on. I've never done it myself. I think it's best to just use PHD2's drift alignment tool via your autoguide scope, plus platesolving to accurately locate end centre the target instead of doing all that time-consuming star alignment. Some people use SharpCap Pro, or PoleMaster, if you're rich...

Hth

Louise

ps SharpCap Pro uses platesolving and can be done via a finder guider 

Edited November 21, 2019 by Thalestris24

[PeterCPC]

14 hours ago, hornedreaper33 said:

Hey @PeterCPC, thanks for the reply. I'm just following instructions on the hand controller, sync with a star then the mount slews to where the star would be if your PA was correct and you bring it back to centre with Alt-Az adjustment. Hey presto. 

I've had this be pretty good in the past but the only thing I can think I was doing differently is how I moved to the first go-to alignment star. I usually disengage the RA and Dec clutches and move manually to centre the star in the finder. Engage the clutches and centre on screen with the hand controller. This time I did it all using the hand controller however, this would only affect go-to accuracy right??

Confused. We have a very good night coming up tonight and I hope I can get my PA dialled this time. I would like to use the polar alignment feature on sharp cap but I think my focal length is undesirable for that.

If you are going to use ASPA then forget about the polar scope and do NOT disengage the clutches. I have attached my aide memoire as to how I used to use ASPA and I always got a good PA. Polemaster is so much better and can be done in a few minutes.

Peter

Telescope Set Up Checklist.docx

[hornedreaper33]

Thanks for the replies all. 

I don't think the OP was particularly clear. Sorry about that. What has come out of though is two things. I should have been updating my go-to alignment after ASPA, duh! Also I think for my location on that night Capella was a poor choice for PA. Lessons learnt. 

I need a better finder so I can start guiding...

[Thalestris24]

6 hours ago, hornedreaper33 said:

Thanks for the replies all. 

I don't think the OP was particularly clear. Sorry about that. What has come out of though is two things. I should have been updating my go-to alignment after ASPA, duh! Also I think for my location on that night Capella was a poor choice for PA. Lessons learnt. 

I need a better finder so I can start guiding...

You might be better off with an oag on a c8. The avx tends to have a lot of DEC backlash - something to bear in mind.