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CGEM-DX will not guide in dec

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#1 Stargazer78

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Posted 30 August 2013 - 03:51 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?

#2 T1R2

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Posted 30 August 2013 - 04:05 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.

#3 cn register 5

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Posted 30 August 2013 - 06:22 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

#4 ohata0

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Posted 30 August 2013 - 08:32 AM

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

#5 rmollise

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Posted 30 August 2013 - 08:55 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.

#6 David Pavlich

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Posted 30 August 2013 - 10:20 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

#7 dragonslayer1

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Posted 30 August 2013 - 09:29 PM

Please keep us posted how it works out
Kasey

#8 Stargazer78

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Posted 30 August 2013 - 09:34 PM

Gonna try again tonight. Fingers crossed lol

#9 Peter in Reno

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Posted 30 August 2013 - 09:53 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

#10 A. Viegas

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Posted 30 August 2013 - 10:01 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

#11 Stargazer78

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Posted 30 August 2013 - 11:52 PM

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??,

#12 Alph

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Posted 31 August 2013 - 02:05 AM

At most undo sync.


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

#13 Stargazer78

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Posted 31 August 2013 - 02:49 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.

#14 mskillen

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Posted 31 August 2013 - 04:14 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.


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

#15 rmollise

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Posted 31 August 2013 - 07:58 AM

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. ;)

#16 dragonslayer1

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Posted 31 August 2013 - 08:44 AM

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

#17 orion69

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Posted 31 August 2013 - 08:58 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.


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.

#18 Stargazer78

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Posted 31 August 2013 - 11:18 PM

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.

#19 Stargazer78

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Posted 31 August 2013 - 11:51 PM

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

#20 orlyandico

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Posted 01 September 2013 - 02:23 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.

#21 Stargazer78

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Posted 01 September 2013 - 03:15 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.


So what am I supposed to do? I bought this mount for astrophotography. The manual doesn't tell me how to do a pec training and honestly I have no idea what that is? I am beyond frustrated at this point!

#22 cn register 5

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Posted 01 September 2013 - 03:30 AM

Try guiding. This will cope with the uncorrected PEC and the dec drift if you aren't perfectly polar aligned.

How much Astrophotography have you done before? Are you just starting or are you moving to a longer focal length?

Chris

#23 Stargazer78

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Posted 01 September 2013 - 03:42 AM

Lol. That's my issue I cannot guide at all. That's why I believe I need the beta fix.

#24 A. Viegas

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Posted 01 September 2013 - 07:58 AM

Ok... Have you used PHD before? Check your settings or post them here. Next verify your polar alignment by re-aligning on two different alignment stars and calibration stars and then check your polar alignment display... Then if necessary redo the ASPA on a star close to the meridian and celestial equator... celebrai or rasalthague should do fine...

Now when you are running PhD are you seeing large spikes in the guiding graph? If so then the guiding problem can be more software than hardware... If your guiding graph does not show big deviations and yet the guiding is still poor with oblong stars as short as 60 seconds then you could have a bad CGeM. If It's still under warranty, send it back, if not then try the beta motor control software...

Oh last comment, what FL are you shooting at? If you are imaging at under 1,000mm then it is a real shame and your CGEM could hve a really bad 8/3 and cogging issue...

Al

#25 Stargazer78

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Posted 01 September 2013 - 08:14 AM

setup is a AT8IN 800 mm focal length with a orion 80 mm short tube guide scope using an orion auto guider. I start off doing the 2 alignment stars followed by the 4 calibration stars.after that is done I slew the scope south to nunki. I start up the polar alignment routine. Instead of using a reticle eyepiece I use my autoguider with phd guide. I turn on phd with the bullseye. I follow the routine for pa and place nunki right in the center. I will then observe for any drift. I observe for 15 minutes. Once there is no drift. I then confirm the polar alignment routine. I then check my polar alignment display and it will read 00 00 00 for both AZM and ALT. I then go to my target and fire up phd again. Once im guiding I check the phd graph and I get a saw tooth pattern and at times the graph jumps off the chart.i tried unguided and I cant even get 60 second exposures with out trails. I dont understand how I can see no drift when I polar align but my guiding is terrible! Its not making any sense and I am so frustrated!






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