Jump to content


Photo

HC polar align and goto align

  • Please log in to reply
8 replies to this topic

#1 philming

philming

    Lift Off

  • -----
  • Posts: 18
  • Joined: 18 Apr 2011
  • Loc: France

Posted 21 April 2011 - 03:14 AM

Hi all !
Simple question. If I want to do a polar align via my HC on my CG5-GT, i'm supposed to have done a 2 star align beforehand. Then I can access the polar align routine. Since I'm then fiddling with the mount's position physically, not just via the HC, I suppose i must do the 2 star align AGAIN after the polar align ?
Is this right ?

Thanx for your help !

#2 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15470
  • Joined: 06 Jul 2007

Posted 21 April 2011 - 04:53 AM

Hi all !
Simple question. If I want to do a polar align via my HC on my CG5-GT, i'm supposed to have done a 2 star align beforehand. Then I can access the polar align routine. Since I'm then fiddling with the mount's position physically, not just via the HC, I suppose i must do the 2 star align AGAIN after the polar align ?
Is this right ?

Thanx for your help !


That is correct. Although I've been _told_ the new AllStar align takes the movements you make in polar aligning into account.

#3 philming

philming

    Lift Off

  • -----
  • Posts: 18
  • Joined: 18 Apr 2011
  • Loc: France

Posted 21 April 2011 - 06:04 AM

Thanx for you're input. Have you been able to verify this ?

#4 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4525
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 21 April 2011 - 10:18 AM

Doing an alignment after doing an 'All Star' polar alignment is not necessary. I have used 'All Star' on my CG-5 and CGEM and even after physically moving the mount a long way the accuracy of the align is not effected. You can 'Undo sync' and realign the mount to your alignment stars, but I've found that for visual this is not required.

Stan

#5 DaveJ

DaveJ

    Surveyor 1

  • *****
  • Posts: 1698
  • Joined: 07 Jan 2005
  • Loc: NE Ohio

Posted 21 April 2011 - 11:19 AM

Thanx for you're input. Have you been able to verify this ?


Actually, you do NOT need to do another alignment following the AllStar Polar Alignment routine assuming you've done a 2-star PLUS 3 or 4 calibration star alignment followed by the AllStar PA routine. Even moving the mount physically in ALT and AZ during the ASPA is compensated for by the HC firmware. I do this regularly with my CGE (same exact firmware as you have in the CG5) Granted, it seems like magic, but it works - the firmware is aware of the model of the sky that the 2+3(or 4) builds, how much the PA routine moved the mount and in what direction, and can compensate accordingly. Of course, it does no harm to shut down and re-align but it really isn't necessary. I've tried it both ways and the final model wasn't any better with the total re-align than with the no-realign method. YMMV.

#6 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27324
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 21 April 2011 - 09:30 PM

I would recommend that you go beyond the 2 star align and do at least 2 stars on each side of the meridian, preferably 2+4 then the PA routine. Your pointing model will be much better.

David

#7 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15470
  • Joined: 06 Jul 2007

Posted 22 April 2011 - 06:00 AM

Thanx for you're input. Have you been able to verify this ?


No...I'll admit...I'm still using the old Polaris Polar Align rountine in the pre AllStar build. But...one of these days I will switch over to the new stuff. :lol:

#8 nganga

nganga

    Vostok 1

  • -----
  • Posts: 116
  • Joined: 16 Mar 2008

Posted 24 April 2011 - 07:44 PM

Hi all !
Simple question. If I want to do a polar align via my HC on my CG5-GT, i'm supposed to have done a 2 star align beforehand. Then I can access the polar align routine. Since I'm then fiddling with the mount's position physically, not just via the HC, I suppose i must do the 2 star align AGAIN after the polar align ?
Is this right ?

Thanx for your help !


It's recommended, but not strictly required. After I do a 2+3 then ASPA, the gotos are very good. Sometimes the goto is so good that the red dot hides the next star that you slew to. I have been able to get 4 minute guided subs with a 500mm refractor with this. Haven't tried imaging with any longer focal length.

Clem

#9 philming

philming

    Lift Off

  • -----
  • Posts: 18
  • Joined: 18 Apr 2011
  • Loc: France

Posted 02 May 2011 - 08:59 AM

Done the test, sorry it doesnt work. I started with a polar align (physical, through the PA scope), then made a perfect alignment with 2 + maximum sync stars, with reticulated EP, so I know I was sharp on the stars. I've done the HC polar alignment right after, then slewed to a big recognisable star. and it was off. Should have been right on :-/






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics