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CG5-AGST general alignment frustration

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#1 A. Viegas

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Posted 06 October 2012 - 02:56 PM

So on Friday I moved the C8 on the CG5-AGST from its usual spot out in the front to a much worse sky but arguably safer spot in the fenced in backyard. So from 8pm through midnight last night I experienced Polar Alignment Hell. Backyard spot has a hill blocking Polaris, so no Chainsaw solution here... Nevermind I thought... with ASPA I figured no big deal. Got it pointed north as per trusty Iphone compass and proceeded to start the alignment process. Talk about way way off target, first slew to alignment star Vega -- like 30 degrees off target. First run through on Polar alignment after 4 calibration stars was 20 degrees off! Yuck! So picked up tripod, rejiggered it, made sure level, checked scope setup to make sure I was still in North America and tried again... and again and again... Finally, after literally 3 hrs of incrementally getting my polar alignment error down to just a couple of degrees and using the AL+AZ knobs to adjust I got it good and center. Re-did the alignment and polar was almost perfect. Whew... Figured I'd slew to M57... way off target. hmmm.. As I had aligned on Vega, slewed to Vega... holy smokes, it was 5 degrees away!... Talk about frustration...

Never had this problem in the front yard...

Anyone else ever experience this nutty behavior with their CG5-AGST? I am running the latest firmware... If I can't get it to work better tonight, I am just going to move it to an even worse part of the yard where at least I get a glimpse of Polaris... Ugh! :bawling:

Al

#2 RTLR 12

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Posted 06 October 2012 - 03:26 PM

Al,

Your 2 star + 4 star alignment has nothing to do with polar alignment. If you don't have the RA axis close to the polar axis, you're going to have to move the mount. Compass apps in cell phones prove to be unreliable. Get a real compass or find some other means of more accurately pointing the mount to the north before you start your alignments. Once you have started your alignment you can not move or re-level the mount. You can move the mount in AZM when doing your ASPA, but try to keep your movement to a minimum. Do not re-level the mount and do not release the clutches.

Stan

#3 A. Viegas

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Posted 06 October 2012 - 03:30 PM

Thanks Stan. I sort of figured I was moving it way way too much... Looks like I am going to have to move it to a spot I can see Polaris...

#4 Stew57

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Posted 06 October 2012 - 03:34 PM

What some have done is when you slew to the first alignment star, moove the mount to center the star. Turn the mount off and start again. You should be closer to polar aligned. Make sure to redo alignment after ASPA or you goto can be off if you had to move the mount much.

#5 A. Viegas

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Posted 06 October 2012 - 05:42 PM

Cool idea, thanks Mark. I will try that tonight

#6 JS999R

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Posted 06 October 2012 - 06:59 PM

I would restart everything as if its a brand new mount. Instead of military time use civilian time, am and pm. For longitude and latitude use the city database instead of punching in your latitude and longitude. Since you can't see Polaris I would use the measuring tool (protractor?) and place in on the saddle to achieve the correct latitude and not depend on the mount's latitude scale, which are known to be inaccurate. I would use a compass to ascertain longitude and adjust for same with the azimuth knobs on the front of the mount.

I had a hellava time aligning my mount after I bought it and it wasn't until I started over and made a couple changes like those above. Another thing to be aware of and I'm sure you are is balance, I believe thats important too.

#7 oldstargazer

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Posted 06 October 2012 - 10:27 PM

You probably had a very good polar alignment when you had it out front. As I have posted here before if you have the mount precisely aligned and then place it down where it is way off you are far better just doing factory reset so it doesn't have any clue what it has used before because that will throw it off and make you go crazy. Believe I have been through exactly what you describe and it always occured when I sat the mount down way off from where it had been on the last go round. I now have marks on the ground where it goes so it is always very close and only requires very small adjustments for polar alignment.
I also got to where I would get started on alignment at dusk so it is way easier to find the stars it is looking for incase it was off because that way only the bright ones that it wants you to use are visible.
I don't have to do that anymore since I have been sitting this thing down long enough now that I can sit it down even in bright daylight and have it pointed almost directly at polaris just based on the surroundings. With practice it will get that way for you.
I would go where you can see polaris and get your bearings so you can pretty much tell where it should be even though you can't see it. I say that because depending on what part of the country you live in magnetic north might not be really north when compared to polaris.
Good luck and again that behavior is normal when the mount it placed on the ground way off in comparison to when it was last precisely aligned.

#8 YetAnotherHobby

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Posted 07 October 2012 - 04:29 PM

While I do not have direct experience with the CG5 AST, I do have a CGEM that was doing pretty much what you are experiencing - initial goto to the first alignment star wasn't even in the same galaxy, never mind a 40mm eyepiece. Even after two alignment stars and a calibration star, the second calibration star was also way off. What seemed to work was to perform a factory reset of the mount. The benefit of that is that it forces you to re-enter everything time and location related. I found that even information that LOOKED GOOD on the HC had to be re-entered...as if the internal calculations were working off some other value than the one displayed. This sort of "reboot" worked, although it was a pain to have to re-enter all that data each time I used the mount.
A couple of months ago I downloaded the HC and MC update tools from Celestron and upgraded the firmware on my mount. I no longer need to perform the factory reset, so it seems they have exorcised that particular bug.

HTH

Geoff

#9 bogg

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Posted 08 October 2012 - 09:05 AM

I have had the same response from my CG5 being 30 degrees off on alignment stars. Later choosing an alignment star to use in an area of the sky, if I slewed back to it, it would be out by a few degrees. My HC is older and not flashable, so I have had to work with it. I found that after resetting to factory defaults and only using standard time all year round I have not had glitches often. Actually for the last month when the skys agree I have woke up my scope from hybernation and input new time and date slewed to an object and amazing it is within a 25 mm eyepiece. :jump: :jump:

#10 Raginar

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Posted 08 October 2012 - 11:11 AM

My 30-degrees off was fixed when I re-did the motor calibration. Once you're aligned, you do it, and it will program the mount for the weight of the scope and the final slew to target.

Good luck!

Chris

#11 George N

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Posted 08 October 2012 - 08:51 PM

My 30-degrees off was fixed when I re-did the motor calibration. Once you're aligned, you do it, and it will program the mount for the weight of the scope and the final slew to target.

Good luck!

Chris


"motor calibration"???? Where is that in the menu??

#12 A. Viegas

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Posted 08 October 2012 - 09:08 PM

I think you can do an RA index calibration, AFTER you have done a ASPA and then re-do a full alignment process with2+4... that resets the HC and it should make future alignment closer to spot on for first two stars.

Al

#13 Stew57

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Posted 08 October 2012 - 10:32 PM

When doing an alignment the mount assumes a perfect polar aligning and index mark alignment. the more these are off the more the first stars will be off. This assumes all location/time data is correct also of course.






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