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Equipment Discussions >> Mounts

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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
cge-pro no tripod $500 cheaper/PE numbers
      #5846994 - 05/08/13 01:10 AM

Not sure if this was posted but saw that Celestron is now selling the CGE-Pro without the tripod. It's 500 cheaper.

Celestron CGE-Pro

Celestron is also posting their PE numbers for the CGE-Pro. Guided, unguided, with PEC and without PEC. Some interesting reads.

I also found this interesting:

And of course, the CGE Pro is also fully T-Point compatible (available from Software Bisque) for ultra precise pointing across the entire sky.

Just found it interesting..


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: cge-pro no tripod $500 cheaper/PE numbers new [Re: wolfman_4_ever]
      #5846995 - 05/08/13 01:14 AM

Quote:

The following graphs display R.A. worm gear tracking accuracy of the CGE Pro Equatorial mount in 4 conditions: Figure 1 – Raw unguided tracking that isolates the periodic error; Figure 2 – Tracking with Permanent Periodic Error Correction (PPEC) enabled; Figure 3 – Guided tracking with an autoguider; and Figure 4 – Guided tracking with an autoguider and PPEC enabled. Data was acquired from Celestron’s engineering team using an EdgeHD 800 optical tube and NexImage camera at f/10. This data represents the typical performance of a CGE Pro under average seeing conditions from urban skies in Torrance, CA. Figure 2 has a cubic fit applied to the graph, and Figures 1, 3 and 4 have linear drift removed (to better show repeatable error). All Figures show 22 minutes of tracking, which covers 4 full rotations of the CGE Pro R.A. worm gear.


Figure 1. This graph displays the R.A. worm gear tracking accuracy for a typical CGE Pro equatorial mount. The graph shows 4 periods of the worm gear which yields about +/-7 arc seconds of periodic error. The minimal periodic error is both very predictable and gradual, allowing short unguided images to be taken, or much longer exposures with extremely accurate tracking when used with an autoguider.


Figure 2. With the CGE Pro’s Permanent Periodic Error Correction (PPEC) enabled, most of the periodic error is eliminated, leaving behind lesser tracking errors caused by atmospheric turbulence, wind, and opto-mechanical flexure. PPEC brings the CGE Pro’s R.A. tracking accuracy to about +/-2 arc seconds, allowing even longer unguided exposures (for uses like Hyperstar imaging).


Figure 3. Autoguiding with the CGE Pro provides consistent tracking accuracy to within +/-2 arc seconds under average seeing conditions. Autoguiding provides an easy way to sustain long-exposure astro-images without excessive tracking error or drift.


Figure 4. With autoguiding and PPEC enabled, we can take full advantage of the CGE Pro’s stability and tracking accuracy. Even under average seeing conditions, PPEC + autoguiding easily yields tracking accuracy of less than +/-2 arc seconds. Note that tracking errors of the mount have dropped so far below the noise floor set by the seeing conditions that they cannot be quantitatively distinguished from zero. This combination will provide the best tracking accuracy, resulting in sharp, round stars in your astro-images.


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Whichwayisnorth
Pooh-Bah
*****

Reged: 07/04/11

Loc: Southern California
Re: cge-pro no tripod $500 cheaper/PE numbers new [Re: wolfman_4_ever]
      #5847505 - 05/08/13 10:37 AM

What I find interesting about this data is that Celestron for a while there was advertising the PE as closer to 3. Now they've increased it to 5. I guess they were having trouble being consistent. Furthermore, as the specs now claim +/-5, I notice that the graph shows 7. All of this was of course done with an 8" OTA which weighs nothing at all compared to the 90lb instrument capacity that the mount advertises. I have an 8" Edge. I don't think I'd even need a counter weight on the CGEPRO. Put an 11 or 14" on there and re-run those tests. I'd be very interested in the differences.

Edited by Whichwayisnorth (05/08/13 10:39 AM)


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: cge-pro no tripod $500 cheaper/PE numbers new [Re: Whichwayisnorth]
      #5847675 - 05/08/13 12:30 PM

That +6/-7 is assuming the very tips of the peaks. But there's seeing noise there. If they low-pass filtered the data a bit to get rid of the spikes, I think it would meet the +5/-5.

Also (admittedly I only noticed this on my Mach1) the PE doesn't change whether it's carried 10lb or 40lb. So perhaps the CGE Pro behaves the same?


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: cge-pro no tripod $500 cheaper/PE numbers new [Re: orlyandico]
      #5848567 - 05/08/13 07:46 PM

Weight wouldn't change the PE unless the balance was way off..

Let me rephrase.. weight shouldn't change the PE.


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