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skyguy55
super member
Reged: 09/23/07
Posts: 162
Loc: Vancouver B.C. Canada
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Hi There,
I have a new (to me) CGE which is replacing my EQ6 PRO. The Hand Control has been updated to the newest version. After leveling the mount and using the polar scope to get close to alignment, I turn the power on and I start the two star alignment. Center two different stars on the same side of the meridian and then sync on four different stars on the other side of the meridian. So far, the GOTOs have always been on my CCD chip after this procedure. When I go to the Polar Align feature in the H/C, it asks to sync to a specific star after centering. After pressing 'Enter' the H/C calculates where that star should be after the 'Sky Model' that was just created. Now, the Allen keys are used to adjust the Az/Alt on the mount. Is there any way to get your alignment back after moving the mount or do you have to power down the mount and start the alignment process all over again?
On a side note, what's the best way to use that Polar scope?
Thanks for any help/ideas.
Gregg
--------------------
WO FLT 110mm
Equinox 80mm
Celestron CGE
DSI-C, DSI PRO, DSI II
Canon 350D
and lots of other 'stuff'
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Randy Roy
sage
Reged: 10/07/05
Posts: 423
Loc: Tennessee
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Hmm. I do not lose my goto alignment after performing the All Star alignment. I also use a polar alignment scope. I find it helpful in getting a reasonably close initial alignment (usually 10 arcmin or less). I do a 2+3 alignment, All Star and then my gotos, like yourself are generally centered on the chip or very near the FOV. If I synch on a nearby star, they are virtually always centered on the chip.
I suppose it is possible that if your initial polar alignment is way off, then your goto alignment could be affected, but since I use the PAS, I have never had a terrible initial alignment. I would check the polar scope after the All Star alignment and make sure the PAS is close to correct.
I've quickly grown to love the All Star polar alignment. I may never drift align again.
Randy
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skyguy55
super member
Reged: 09/23/07
Posts: 162
Loc: Vancouver B.C. Canada
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Hi Randy,
Hmmm, I have only set the mount up a few times and twice, after I did the Polar align, the star was still on the CCD chip so moving the mount was minimal. The other two times the star fell off the chip and had to remove the CCD camera and replace with an eyepiece to find out where the alignment star had gotten to. At that point I realized there could be a problem with the GOTOs. I see how critical getting that initial alignment with the PAS is now.
Is there an documentation on how to set up the PAS?
It sure is a great mount. I'm going to try NexRemote on the weekend.
Thanks Randy, very much appreciated.
Gregg
--------------------
WO FLT 110mm
Equinox 80mm
Celestron CGE
DSI-C, DSI PRO, DSI II
Canon 350D
and lots of other 'stuff'
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Arbacia
scholastic sledgehammer
Reged: 04/18/07
Posts: 788
Loc: Madrid, Spain
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I am not using Polar finder, I just trust in the polar alignment routine. Polar should be near the AR axis, but I got alignments beyond 10º (which is a lot!)
If you have the last firmware, after polar alignment it is not necesary to reset the mount and align again and the thing should be aligned. As far as I know there is no routine to go back.
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LightBridge 12", 70´s C8, C11. CGE. ETX125
Set of Takahashi LE EPs; Ethos; DMK 31AF03.AS
CN image gallery
http://www.astrohenares.org
http://www.asociacionhubble.org
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rmollise
Postmaster
Reged: 07/06/07
Posts: 5279
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Quote:
Hi There,
I have a new (to me) CGE which is replacing my EQ6 PRO. The Hand Control has been updated to the newest version. After leveling the mount and using the polar scope to get close to alignment, I turn the power on and I start the two star alignment. Center two different stars on the same side of the meridian and then sync on four different stars on the other side of the meridian. So far, the GOTOs have always been on my CCD chip after this procedure. When I go to the Polar Align feature in the H/C, it asks to sync to a specific star after centering. After pressing 'Enter' the H/C calculates where that star should be after the 'Sky Model' that was just created. Now, the Allen keys are used to adjust the Az/Alt on the mount. Is there any way to get your alignment back after moving the mount or do you have to power down the mount and start the alignment process all over again?
On a side note, what's the best way to use that Polar scope?
Thanks for any help/ideas.
Gregg
If you follow the instructions for AllStar in the manual (the CGEM Manual is the only one with instructions for it at the moment, I beleive), you can get your go-to back without power-down. They recommend you unsync the polar alignment star, and check/replace the two go-to alignment stars.
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Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
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freestar8n
sage
Reged: 10/12/07
Posts: 387
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Quote:
If you follow the instructions for AllStar in the manual (the CGEM Manual is the only one with instructions for it at the moment, I beleive), you can get your go-to back without power-down. They recommend you unsync the polar alignment star, and check/replace the two go-to alignment stars.
Yes - you do not want to shutdown the mount, except perhaps to hibernate if you want - since that takes time and requires re-finding the switches. One of the big wins of AllStar is that you polar align and then go direct to observing.
If you intend to observe far from the alignment star, you probably want to unsync after polar alignment. If you intend to observe near the alignment star, you probably want to leave it sync'd.
If you find that GoTo isn't as accurate as you would like, particularly in some other part of the sky, you can replace alignment stars. You can use different stars for that, and to save time you can use the polar alignment star as one of them, if you didn't already.
But definitely don't power down unless you need to for some other reason.
Frank
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CounterWeight
Carpal Tunnel
Reged: 10/05/08
Posts: 1609
Loc: PDX chronoplast
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I've just always followed the method Rod pointed out in the CGEM manual - and really it's a lot like the old 2 by 4 method. My experience has been that by unsyncing from the align star and re-aligning all my goto's wherever I point are 'on the chip'. This is good as they were centered on chip before I did the upgrade - and as I can see polaris I was thinking I like the original more - especially in terms of the way the re-align workflow after PA works.
I wish C would have included a decision branch at the very beginning where you could choose which one to use depending on if you could see Polaris or not. Either way I am using the wrench which is no change, but I just prefer the original method workflow for realignment as it was a few minutes faster overall.
I dont like the workflow of the 'replace' align and sync feature in the newer software, esp compared to just doing a fresh align - cal, as in the older version where the stars are again suggested and slewed to.
If I had no way to view polaris I think the the all star would be wonderful.
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Clear skies - Jim
 - 
CGE (Constant Get Errors), A-P Mach1?
Onyx 80ED, Tak FS-128, TEC APO160ED
CCD: Orion SSPDSCIv2, SSI3, SSAG
diags, ep's, tubes, filters, Binocs
My CN Image Gallery
Experience is a difficult teacher, it gives the test first, and gives the lesson later
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freestar8n
sage
Reged: 10/12/07
Posts: 387
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Quote:
I wish C would have included a decision branch at the very beginning where you could choose which one to use depending on if you could see Polaris or not. Either way I am using the wrench which is no change, but I just prefer the original method workflow for realignment as it was a few minutes faster overall.
I'm surprised you say this, because the old version REQUIRED you to find the switches again, and then to do a new alignment - as if restarting from scratch. I'd be surprised if the new version isn't faster in most cases - especially if you are aligning on a star in a region you already intend to view, or one that is already an alignment star. The main win is if you don't need to realign after the polar align - that saves time on finding switches, and on doing a second alignment. If you work the polar alignment into the 2-star alignment process, sharing one star in the south, the whole thing is very efficient - if speed and accuracy are concerns.
Frank
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CounterWeight
Carpal Tunnel
Reged: 10/05/08
Posts: 1609
Loc: PDX chronoplast
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Frank,
Don't be surprised. I've used the mount for visual and imaging every possible night since purchase, with several differnt scope setups. So I am not talking hypothetical here. Find switches takes all of 10 seconds, not an issue. Slewing through the menu lists and keys to replace the align stars and cal stars takes far more time, not to mention I still must slew to the star to replace it. The suggested method does say to unsync from the PA star and replace align star. (It is interesting here to see what and how much correction has been made) I always take 2 align and 4 cal stars on each side of the PA, and have found doing so keeps the goto and tracking as good as I can hope without drifting or iterating, all sky sectors and pretty much all night. At any rate, perhaps it ends up a wash, but I feel the workflow to accomplish this is a bit longer and more tedius in the allstar - please, this is just an opinion.
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Clear skies - Jim
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CGE (Constant Get Errors), A-P Mach1?
Onyx 80ED, Tak FS-128, TEC APO160ED
CCD: Orion SSPDSCIv2, SSI3, SSAG
diags, ep's, tubes, filters, Binocs
My CN Image Gallery
Experience is a difficult teacher, it gives the test first, and gives the lesson later
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freestar8n
sage
Reged: 10/12/07
Posts: 387
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Hi-
Well - I guess we have opposite tolerances for switches and menus. True, I don't like bouncing around the menus, but I really don't like waiting for the switches. Plus, a key change is, there is a loss of calibration accuracy after re-finding the switches - which is avoided with Allstar.
Anyway - I think there is a misunderstanding of the manual with regard to what is needed after AllStar. It says to check the accuracy after alignment. If it is adequate for your needs - you are done. It does say to do an unsync - but only if you need to replace alignment stars (because in that case you have to). You may be fine leaving it sync'd - especially if you observe near the alignment star. And you may find that far away from that star, you are better off unsyncing even without adding alignment stars. These are things you can do, or not do, depending on how you find the accuracy behaves.
But - if you want maximum accuracy and you don't mind doing 2+4, align, 2+4 - and if you don't like menus - the best thing might be to do the allstar align and then just turn off the mount, then turn it back on. That will force a re-find of the switches, but that is ok if you then do a 2+4. Having the mount do a fresh alignment will make menu navigation easier since it prompts you for align and cal stars. I wouldn't recommend this in general - but it sounds like it might be a good compromise given your preferences.
Frank
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Bowmoreman
Post Laureate
Reged: 09/11/06
Posts: 4117
Loc: Bolton, MA
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Its really mostly about what USE you are going to use the aligned mount for... if it is for AP, then I strongly suggest just doing: 2+4, PAS, 2+4, PAS, 2+4... and then you are DONE - should be close enough for 5-10 minute subs in my direct experience.
I just don't find redoing the alignment on the CGE all that "taxing"... and the quickness of getting a VERY close Polar alignment is frankly quite impressive to me...
So, never did it any other way... Now it's all moot, since I've replaced it with the MI-250 (which has a similar alignment protocol).
clear enough skies
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Dave
Imaging: MI-250+ADM/SBS/Optec Libra: C11Hyperstar,TMB80SS
Visual: XT10i RTP
EP: 31T5,22T4,17T4,12T4,13Ethos,10XW,8Ethos;2x Powermate,Paracorr, 1.6X Antares, Hyperion8-24Zoom
Cameras: Mallincam Color Hyper Plus, QHY8
Guider: SBIG STV eFinder
Key Add-ons: Gerbings Heated clothes, WilderSkiesObservatory(BYO#90), Speco 9"Monitor
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freestar8n
sage
Reged: 10/12/07
Posts: 387
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Quote:
Its really mostly about what USE you are going to use the aligned mount for... if it is for AP, then I strongly suggest just doing: 2+4, PAS, 2+4, PAS, 2+4... and then you are DONE - should be close enough for 5-10 minute subs in my direct experience.
I just don't find redoing the alignment on the CGE all that "taxing"... and the quickness of getting a VERY close Polar alignment is frankly quite impressive to me...
Wow - 18 star alignments and two polar aligns. Certainly if you don't mind it - there is no downside to using all those stars. But in practice, I don't think the cal stars are so needed again if the switches weren't re-found. So I think 2+4 is needed for the first PAS, and the second PAS may be desirable, but your accuracy may not be a lot different from:
Turn on, find switches, 2+4, PAS, unsync, 2+0, [Check polar alignment values. If bad, then PAS again] go direct to target, sync on target.
This is more what I do for my images when I set up fresh. I need an accurate polar alignment, but the goto accuracy after the last allstar is adequate to find the object on the chip and then I sync locally.
As long as the switches aren't re-found, the calibration based on the first 2+4 should still be pretty good, so you can do 2+0.
The 2+0 allows me to check the estimated polar align error. If it looks good, I will start imaging. Otherwise, I do PAS again.
Frank
CGE images
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David Pavlich
Postmaster
Reged: 05/18/05
Posts: 9649
Loc: Mandeville, LA USA 30.22 X 90....
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As a former CGE owner, I have a question or two about the new PA routine. If you do an electronic alignment using the HC to center the stars and add to your pointing model then do a PA routine where the star is centered by mechanically adjusting the mount, how does the electronic side know how much you've moved the mount in order to retain the original pointing model?
It seems to me that it is no different than if you did an electronic align and somehow moved one of the tripod legs or allowed the mount to slip on either the RA or Dec clutch.
In other words, after moving the mount mechanically, I'm having a difficult time understanding how the original pointing model could work. The mount configuration has changed AFTER the electronic align was completed. Help?
David
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Proud Member; PAS NOLA,
"If we knew what we were doing, it wouldn't be called research..."
A. Einstein
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skyguy55
super member
Reged: 09/23/07
Posts: 162
Loc: Vancouver B.C. Canada
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Quote:
As a former CGE owner, I have a question or two about the new PA routine. If you do an electronic alignment using the HC to center the stars and add to your pointing model then do a PA routine where the star is centered by mechanically adjusting the mount, how does the electronic side know how much you've moved the mount in order to retain the original pointing model?
It seems to me that it is no different than if you did an electronic align and somehow moved one of the tripod legs or allowed the mount to slip on either the RA or Dec clutch.
In other words, after moving the mount mechanically, I'm having a difficult time understanding how the original pointing model could work. The mount configuration has changed AFTER the electronic align was completed. Help?
David
Hi David,
I'm with you on this one. I don't understand how a "Sky Model" can be created and then move the mount and expect to have the same accuracy as the mount had before you moved everything. I have only been able to set up the CGE a few times but I did find it odd to go through the 2 and 4 star alignment and then physically adjust the mount and expect to retain my pointing accuracy. I can see that if you can get very close to alignment by initially using the Polar scope, the 2 and 4 star alignment will go very quickly so then the final Polar adjustments should be very small. I would think that powering down the mount and redoing the 2 and 4 star alignment again should put all stars on your CCD chip and then just centering as a final adjustment.(?) That shouldn't take too much time to redo the alignment should it?
I guess I will have to try both ways and see what happens. I did find the manual for the CGE PRO (Thanks Rod) and have made notes on the procedure.
Thanks again everyone.
Gregg
--------------------
WO FLT 110mm
Equinox 80mm
Celestron CGE
DSI-C, DSI PRO, DSI II
Canon 350D
and lots of other 'stuff'
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David Pavlich
Postmaster
Reged: 05/18/05
Posts: 9649
Loc: Mandeville, LA USA 30.22 X 90....
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Quote:
Quote:
As a former CGE owner, I have a question or two about the new PA routine. If you do an electronic alignment using the HC to center the stars and add to your pointing model then do a PA routine where the star is centered by mechanically adjusting the mount, how does the electronic side know how much you've moved the mount in order to retain the original pointing model?
It seems to me that it is no different than if you did an electronic align and somehow moved one of the tripod legs or allowed the mount to slip on either the RA or Dec clutch.
In other words, after moving the mount mechanically, I'm having a difficult time understanding how the original pointing model could work. The mount configuration has changed AFTER the electronic align was completed. Help?
David
Hi David,
I'm with you on this one. I don't understand how a "Sky Model" can be created and then move the mount and expect to have the same accuracy as the mount had before you moved everything. I have only been able to set up the CGE a few times but I did find it odd to go through the 2 and 4 star alignment and then physically adjust the mount and expect to retain my pointing accuracy. I can see that if you can get very close to alignment by initially using the Polar scope, the 2 and 4 star alignment will go very quickly so then the final Polar adjustments should be very small. I would think that powering down the mount and redoing the 2 and 4 star alignment again should put all stars on your CCD chip and then just centering as a final adjustment.(?) That shouldn't take too much time to redo the alignment should it?
I guess I will have to try both ways and see what happens. I did find the manual for the CGE PRO (Thanks Rod) and have made notes on the procedure.
Thanks again everyone.
Gregg
Hey Greg....my experience with the CGE is sans the polar scope. Didn't need it because the PA routine within the CGE was good. So...I would just get the mount close with a compass. Then do the 2 stars on the West then 4 on the East. Then the PA routine. When the PA routine was completed, the mount would automatically go into the startup routine beginning with the switch positions. Then it's 2/4 then image or view.
I did as Dave did, though. I had the CGE in an obs, so I did 2 iterations of the routine and found it was quite close to a drift. It didn't bother me that it took a while because once completed, it was good to go.
As an aside, with my MI250 and Gemini, I do a 3 west, 5 east. Pick a star close to the intersection of the meridian and celestial equator. Center the star with the HC and then invoke what Gemini calls the Polar Axis Correction. When that happens, Gemini slews the mount to where the star should be if the mount is in perfect PA. Center the star mechanically and it's aligned. However, you have to redo the pointing model again. And again, since it's sitting in my obs, I did two iterations. Talk about an accurate pointing model! 
Anyway, this is a great discussion being the mount junkie that I am. 
David
--------------------
Proud Member; PAS NOLA,
"If we knew what we were doing, it wouldn't be called research..."
A. Einstein
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freestar8n
sage
Reged: 10/12/07
Posts: 387
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Quote:
If you do an electronic alignment using the HC to center the stars and add to your pointing model then do a PA routine where the star is centered by mechanically adjusting the mount, how does the electronic side know how much you've moved the mount in order to retain the original pointing model?
The mount only has to assume that the user has done what was requested: move the mount in az and alt to center the star. If that is done well, by those two motions, as requested, then the mount knows what happened and can correct the previous sky model for this change.
In order for this to work accurately, the original sky model has to be good - so a fresh 2+3 or 2+4 has benefit. That way the mount already knows how far the mount is off polar alignment, and how far off the star is. If the mount could move itself mechanically in alt/az, then it could fix the problem on its own. Instead, it asks the user for a hand and assumes the user has done a good job. And since it is all known, it can be modeled.
Frank
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coper4
member
Reged: 03/12/09
Posts: 26
Loc: Walterboro,SC
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In the CGEM book it says to do the alignment procedure and the calibration again after you do the PA procedure. If you look at the CGEM book is is on pages 37 thru 39 I believe
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Celestron CGEM 1100
William Optics dual speed focuser
2" OPT quartz Dielectric Diagonal
Meade 8" Starfinder reflector
Celestron 127MM Powerseeker
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David Pavlich
Postmaster
Reged: 05/18/05
Posts: 9649
Loc: Mandeville, LA USA 30.22 X 90....
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Quote:
Quote:
If you do an electronic alignment using the HC to center the stars and add to your pointing model then do a PA routine where the star is centered by mechanically adjusting the mount, how does the electronic side know how much you've moved the mount in order to retain the original pointing model?
The mount only has to assume that the user has done what was requested: move the mount in az and alt to center the star. If that is done well, by those two motions, as requested, then the mount knows what happened and can correct the previous sky model for this change.
In order for this to work accurately, the original sky model has to be good - so a fresh 2+3 or 2+4 has benefit. That way the mount already knows how far the mount is off polar alignment, and how far off the star is. If the mount could move itself mechanically in alt/az, then it could fix the problem on its own. Instead, it asks the user for a hand and assumes the user has done a good job. And since it is all known, it can be modeled.
Frank
The only way this could work accurately is if the mount has sensors on it to know exactly how much the mount was moved in RA and Dec. As stated in another post, the manual states that the alignment routine should be done again. This is the only way to get the pointing model corrected after moving the mount, whether in RA, Dec or if someone kicked a tripod leg.
David
--------------------
Proud Member; PAS NOLA,
"If we knew what we were doing, it wouldn't be called research..."
A. Einstein
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CounterWeight
Carpal Tunnel
Reged: 10/05/08
Posts: 1609
Loc: PDX chronoplast
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I also did as David suggested and no polar scope needed. Impressive accuracy! and it holds night to night if mount left to hybernate. I also use rougn north but have my 'home' set so polaris is in center 1/4 of a 12mmplossel ep.
I think it's just a sort of 'aliasing' the rotational vector 'reference' direction and magnitude to NCP based on whatever star - say Spica or whatever. The prev model has you align and cone correct then align on Polaris, then re-align, Polaris relation to NCP wrt time is known so entire sky model just needs small correction wrt the reference. From known to known, you have a satisfactory 'quadrilateral' for parallelogram law for resultant vector.
new version... All same except can be WRT any chosen star. Makes no sense to 'move' NCP so just correct back to NCP via aliasing from chosen vector. Just as interative on the original showed relative diffrence between before and after, same is true of allstar (model correction seen by slewing to a star after sync aligning on star of choice after process completed and slewing to original reference object, deviation vector equal in direction and magintude to mechanical correction made - just as in the original[the CGEM manual makes reference to this]) which obviates undoing sync and re-align to adjust new sky model and compensate across the Celestial sphere...
My thinking is that they had a decent pointing model and rather than re-do from ground up, they just realized that as the CS at large is relatively stationary - one could use any star for the mechanical adjustment to the mount, and reverse interpolate and corrections back to a NCP or SCP model with miniscule deviation based more on encoder/bit resolution than any relative motion. If a vector is used then we have a known direction and magnitude to use as a correction, simple and useful? Wether aimed at Polaris or Spica it is a simple uncaring number to use. Starting with a large pool of 'knowns' and ending with same.
All that said... sometimes with the mount set up as mentioned above if I am just doing visual I do a 'planet' align or simple 1 or 2 star align and I'm ok with relatively small corrections needed depending... but heck - I am very accustomed to sky charts and need a reason to still use them To me that's a part of the enjoyment... the iterative and double 2by4 I only use for imaging and have been good out to 12-15 minutes no problem... that is nice to have if needed. Many times I've just had to accept the mount was pointing at something I couldn't see - have it show up center chip after a 6 minute test exposure.
The same is true of the new model if I follow established routine with the all star but I have noticed a bit more deviation from set-up to set-up. I dont think it's the switches as much as the resultant vector and my level of patience and accuracy doing the align - still whatever the error it can be iterated out in the new routine same as old...
--------------------
Clear skies - Jim
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CGE (Constant Get Errors), A-P Mach1?
Onyx 80ED, Tak FS-128, TEC APO160ED
CCD: Orion SSPDSCIv2, SSI3, SSAG
diags, ep's, tubes, filters, Binocs
My CN Image Gallery
Experience is a difficult teacher, it gives the test first, and gives the lesson later
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Chris Rowland
sage
Reged: 02/28/05
Posts: 336
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I think you are all making this far more difficult than it needs to be.
All I do (with an
ASGT and 80mm Oynx) is put the scope down so it's about right, do a 2+3 align then a polar align following the instructions on the HC. The polar align error before can be several degrees and I sometimes have to move the whole tripod because I run out of adjustment with the azm controls.
I don't do any more aligning and from what I can see the polar align error afterwards is about 5 arc minutes.
This gives me gotos that are fine and for imaging a sequence of 60 sec DSLR images over an hour show no rotation over the whole sequence.
The only thing I take care with is centering the stars through the whole alignment process. I use a 25mm reticle EP.
I don't think I've ever realigned, in fact, having come to this without using the previous version, it never occurred to me to do so.
Chris
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