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Equipment Discussions >> Mounts

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Stargazer78
professor emeritus
*****

Reged: 03/05/13

Loc: Susanville California
CGEM-DX will not guide in dec
      #6053815 - 08/30/13 04:51 AM

Tonight was my first actual test of my new DX. I was having issues with my polar alignment routine though. I did the normal 2 star alignment plus 4 calibration stars. I then did the ASPA routine. Instead of an eye piece I used my orion auto guider and PHD. Adjusted both azimuth and elevation until my star was centered in the bullseye. turned off the mount and started up again with the same setup. Found my target and fired up PHD. Once it was guiding I checked the graph and my RA was perfect. My DEC climbed off the chart. What did I do wrong?

Edited by Stargazer78 (09/01/13 12:40 AM)


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T1R2
Pooh-Bah


Reged: 06/11/13

Loc: NeverWhere
Re: Polar Alignment new [Re: Stargazer78]
      #6053832 - 08/30/13 05:05 AM

I think because you turned off the mount, once your aligned go ahead and take a *tour*, I would think if you turn it off you will have to start all over again, I don't have the same mount as you but its similar(CGE) you might have to re-enter your location if it is turned off, unless it remembers it. It was odd that you would have to turn off your mount to start to use it, or use the hibernate function. Make sure your real time clock is on.

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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Polar Alignment new [Re: T1R2]
      #6053900 - 08/30/13 07:22 AM

You need to redo the 2+n alignment after turning the power off.

But if you do ASPA you do NOT need to realign!

At most undo sync.

The ASPA alignment rotates the align model by the amount of the polar align error so as long as you do a good job of centring the PA star in both the Sync and polar align phases gotos should still be OK.

At least try it.

Chris


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ohata0
member


Reged: 03/10/09

Loc: Hawaii, USA
Re: Polar Alignment new [Re: cn register 5]
      #6054050 - 08/30/13 09:32 AM

ah, i keep forgetting that aspa syncs the star. i should try undoing the sync.

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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Polar Alignment new [Re: ohata0]
      #6054081 - 08/30/13 09:55 AM

No turning on or off or redoing the go-to alignment will help his problem. If I read his post correctly, he was showing lots of declination drift while PHD was guiding. That means a problem with polar alignment. Be sure to use a star to the south, one not too high. 30-degrees or so, for ASPA.

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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Polar Alignment new [Re: rmollise]
      #6054213 - 08/30/13 11:20 AM

And if you have the time, do two iterations of the PA routine. It will refine your PA and you'll be happy!

David


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dragonslayer1
scholastic sledgehammer


Reged: 02/25/12

Loc: SLC, UT
Re: Polar Alignment new [Re: David Pavlich]
      #6055233 - 08/30/13 10:29 PM

Please keep us posted how it works out
Kasey


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Stargazer78
professor emeritus
*****

Reged: 03/05/13

Loc: Susanville California
Re: Polar Alignment new [Re: dragonslayer1]
      #6055241 - 08/30/13 10:34 PM

Gonna try again tonight. Fingers crossed lol

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Peter in Reno
Postmaster
*****

Reged: 07/15/08

Loc: Reno, NV
Re: Polar Alignment new [Re: Stargazer78]
      #6055268 - 08/30/13 10:53 PM

I never understand the need to power down the mount after any kind of calibration or polar alignment. If you need to redo the alignment, simply slew to a star, press "ALIGN" button and follow the on screen instructions. It's a lot faster and just as accurate than to power down the mount. It's absolutely unnecessary to power down the mount to redo or check the alignment.

Peter


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A. Viegas
scholastic sledgehammer
*****

Reged: 03/05/12

Loc: New York City/ CT
Re: Polar Alignment new [Re: Stargazer78]
      #6055276 - 08/30/13 11:01 PM

Pick a star close to the Meridian and near the celestial equator... Try Some of the stars in Ophiucus... Like Cebalrai, Altair or Rasalhague as your polar alignment stars in the early evening

Al


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Stargazer78
professor emeritus
*****

Reged: 03/05/13

Loc: Susanville California
Re: Polar Alignment new [Re: A. Viegas]
      #6055393 - 08/31/13 12:52 AM

I used Nunki. Still having the same issue. Guiding great in RA DEC is off the chart. Using default brain settings and my mount says im perfectly aligned??,

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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: Polar Alignment new [Re: cn register 5]
      #6055471 - 08/31/13 03:05 AM

Quote:

At most undo sync.



No need for it and it is easy to verify it.


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Stargazer78
professor emeritus
*****

Reged: 03/05/13

Loc: Susanville California
Re: Polar Alignment new [Re: Alph]
      #6055496 - 08/31/13 03:49 AM

Ok I think I have found a solution. My goggle fu was great tonight! Sine of these mounts were having issues guiding in dec. Example would be my phd guide graph. After searching several old threads frim different sources I stumbled in a topic that celestron was making a firmware solution for this exact problem. Then I thought, hey its after midnight might as well try and see if there was a update and..... yep. I updated my firmware and re did a rough polar alignment through my polar scope. Re dud the alignment and fired up phd. At this point I just wanted to see how the graph was doing. Even though my alignment was off they both tracked decent. They were not running on the center line but I could tell just from the graph that it was improving. If I would of done a proper polar align I'm sure this solved my issue. If someone else has had this issue please chime in and tell me what you did to fix this. Im about 95 percent sure tomorrow night will be good.

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mskillen
member
*****

Reged: 06/07/13

Loc: Maryland
Re: Polar Alignment new [Re: rmollise]
      #6055538 - 08/31/13 05:14 AM

Quote:

No turning on or off or redoing the go-to alignment will help his problem. If I read his post correctly, he was showing lots of declination drift while PHD was guiding. That means a problem with polar alignment. Be sure to use a star to the south, one not too high. 30-degrees or so, for ASPA.




This I didn't know thanks for this info, I guess the reason for this is these stars are further from the celestial pole?
I was just picking a star and going for it before I will try this out and see if it helps me.

Mark


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Polar Alignment new [Re: Peter in Reno]
      #6055669 - 08/31/13 08:58 AM

Quote:

I never understand the need to power down the mount after any kind of calibration or polar alignment. If you need to redo the alignment, simply slew to a star, press "ALIGN" button and follow the on screen instructions. It's a lot faster and just as accurate than to power down the mount. It's absolutely unnecessary to power down the mount to redo or check the alignment.

Peter




The reason for this is that early on, in the days when the polar alignment routine used a single star, Polaris, Celestron did advise you to turn the mount off after the alignment and do a new go-to alignment. That's no longer the case, but it's what people remember. Also, it's not really much harder than hitting the Align button.


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dragonslayer1
scholastic sledgehammer


Reged: 02/25/12

Loc: SLC, UT
Re: Polar Alignment new [Re: rmollise]
      #6055727 - 08/31/13 09:44 AM

Am glad for you Stargazer, I hope the upgrade fixed everything and all is well; again, keep us posted,
Kasey


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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: Polar Alignment new [Re: Stargazer78]
      #6055739 - 08/31/13 09:58 AM

Quote:

Ok I think I have found a solution. My goggle fu was great tonight! Sine of these mounts were having issues guiding in dec. Example would be my phd guide graph. After searching several old threads frim different sources I stumbled in a topic that celestron was making a firmware solution for this exact problem. Then I thought, hey its after midnight might as well try and see if there was a update and..... yep. I updated my firmware and re did a rough polar alignment through my polar scope. Re dud the alignment and fired up phd. At this point I just wanted to see how the graph was doing. Even though my alignment was off they both tracked decent. They were not running on the center line but I could tell just from the graph that it was improving. If I would of done a proper polar align I'm sure this solved my issue. If someone else has had this issue please chime in and tell me what you did to fix this. Im about 95 percent sure tomorrow night will be good.




How is your balance, especially in DEC? If you want decent guiding DEC balance must be spot on and RA little (and I mean little) east heavier.

Edited by orion69 (08/31/13 09:59 AM)


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Stargazer78
professor emeritus
*****

Reged: 03/05/13

Loc: Susanville California
Re: Polar Alignment new [Re: orion69]
      #6056916 - 09/01/13 12:18 AM

Scratching my head at this one. No change in behavior. My phd graph is all over the place. I drifted on nunki for 15 minutes and it stayed centered. My polar align display reads...
AZM:-00 00'01
ALT:-00 00'00
It has to be this coging issue I keep reading about. Any one out there who just purchased this mount have this issue? Im using default settings on the hand control and phd.


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Stargazer78
professor emeritus
*****

Reged: 03/05/13

Loc: Susanville California
Re: Polar Alignment new [Re: Stargazer78]
      #6056956 - 09/01/13 12:51 AM

Cannot get 60s subs even with out guiding!!! This cannot be right????

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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Polar Alignment new [Re: Stargazer78]
      #6057050 - 09/01/13 03:23 AM

You must be using the AT8IN?

If so.. then yes 60 seconds unguided is out of reach.

If you're absolutely sure your polar alignment is dead-on (i.e. no drift in DEC if you turn off DEC guiding in PHD) then you're hitting the large periodic error of the CGEM and CGEM DX.

Try doing a PEC training. This still won't help a lot of your 8/3 error is too large.


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