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(Sorry) Another Q on the CGEM Polar Align sequence

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#1 SanDiegoPaul

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Posted 09 February 2010 - 11:14 AM

Last night I had two hours before clouds came in. WooHOOO! Figured I'd practice the steps in the Polar Alignment. I am SOOOO loving being able to set up in such short order with the GEM!! With the Lx200 and the wedge, there's no way I would have set up last night, knowing it would be foggy & cloudy soon!!

But anyway, on to my question

I started with the GOTO alignment and I used four stars. Then, after taht I got a great Polar Align done (I think) and I proceeded to cancel the Sync on the previous GOTO alignment. When I tried to redo the GOTO alignment, all it would ask me is do I want to replace a star? It doesn't get to a spot where you can just redo the star alignment? WHY?

It asked if I wanted to replace a star. I did, and from then on my GOTO's were horrible. I don't understand why it just won't let you do another star alignment after you complete the Polar Align process.

But I shut it off, and restarted the mount. Doing another 4-star alignment without touching the mount adjustments gave me very good GOTO's for about 5 minutes before cloud cover rolled in.

So there are actually two questions: One, is the steps needed to make that transition when you complete the Polar Alignment and you want to cancel the Sync and do a star alignment. Why is it only asking if I want to replace a star?

Next I want to fine tune my coordinates. When I got first light with the mount, I set it to San Diego from the list of cities and have never changed it. But last night I brought my GPS out to the scope & I wanted to update the mount to exact coordinates. After I entered the date & time into the mount, I pressed UNDO to try getting back to the menu where I could enter coordinates. The only option I got was to cancel. So please, what's the step I am missing here?

Thanks for your help on all this stuff guys! By the time springtime comes and the weather is clear I'll know this mount like an expert and I'll be confident enough to bring the GEM out to the desert with the club. I can't wait to get it set up next to my LX200's pier and be able to image from both scopes at the same time!! :bow:

#2 rmollise

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Posted 09 February 2010 - 11:21 AM

Last night I had two hours before clouds came in. WooHOOO! Figured I'd practice the steps in the Polar Alignment. I am SOOOO loving being able to set up in such short order with the GEM!! With the Lx200 and the wedge, there's no way I would have set up last night, knowing it would be foggy & cloudy soon!!

But anyway, on to my question

I started with the GOTO alignment and I used four stars. Then, after taht I got a great Polar Align done (I think) and I proceeded to cancel the Sync on the previous GOTO alignment. When I tried to redo the GOTO alignment, all it would ask me is do I want to replace a star? It doesn't get to a spot where you can just redo the star alignment? WHY?

It asked if I wanted to replace a star. I did, and from then on my GOTO's were horrible. I don't understand why it just won't let you do another star alignment after you complete the Polar Align process.

But I shut it off, and restarted the mount. Doing another 4-star alignment without touching the mount adjustments gave me very good GOTO's for about 5 minutes before cloud cover rolled in.

So there are actually two questions: One, is the steps needed to make that transition when you complete the Polar Alignment and you want to cancel the Sync and do a star alignment. Why is it only asking if I want to replace a star?

Next I want to fine tune my coordinates. When I got first light with the mount, I set it to San Diego from the list of cities and have never changed it. But last night I brought my GPS out to the scope & I wanted to update the mount to exact coordinates. After I entered the date & time into the mount, I pressed UNDO to try getting back to the menu where I could enter coordinates. The only option I got was to cancel. So please, what's the step I am missing here?

Thanks for your help on all this stuff guys! By the time springtime comes and the weather is clear I'll know this mount like an expert and I'll be confident enough to bring the GEM out to the desert with the club. I can't wait to get it set up next to my LX200's pier and be able to image from both scopes at the same time!! :bow:


You can do another alignment without shutting the scope off if you choose to do that rather than just replace alignment stars. You'll undo out of where you are and just use "Menu" to get to alignments.

Once the telescope is go-to aligned, there's no using GPS again...and no need to. It will do absolutely nothing for you.

#3 SanDiegoPaul

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Posted 09 February 2010 - 11:25 AM

Uncle Rod thanks mucho. I was sure that there had to be another way to align the scope after the Polar was done!

RE: the entry of coordinates: When I go out to our club's dark sky site, I am going to need to change it won't I? Also, next month I'll be in Arizona Sky Village for a couple days.

#4 David Pavlich

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Posted 09 February 2010 - 05:51 PM

Hey Paul...I haven't used the All Star Align, but the old way was to do the 2/4 then polar align. When the polar align was done, the mount would automatically revert back to the 2/4 star alignment routine. So....

You guys that have the All Star Align, does it go through the same routine or does it not go back to the 2/4 and instead offer other options? Paul wants to know. :grin:

David

#5 Fred1

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Posted 09 February 2010 - 06:22 PM

It sounds like that you might be hitting too many buttons. I do a Two Star and then 4 calibration stars. If I want to do a Poalr Alignment then I hit "Align" and scroll to the Polar Align program. Then, I follow the prompts from the HC and all is fine. Just be sure that your last 2 alignment (or calibration stars if you use them) are not too close to the east or west horizons, zenith or celestial pole. There might be other parameters but the HC will tell you. Come to think of it I'm pretty sure that the HC will ask you to replace a star if it's too close to the aforementioned. Be sure you only follow what the HC asks. I'm pretty sure that I get an Align Success message when complete.

I don't use the City Names for coordinates. I get my site coordinates off the web for better accuracy. You can use Google to search. I like the Select From Map function on Heavens Above.
http://heavens-above...ed&alt=0&tz=CET

#6 drksky

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Posted 09 February 2010 - 06:41 PM

RE: the entry of coordinates: When I go out to our club's dark sky site, I am going to need to change it won't I? Also, next month I'll be in Arizona Sky Village for a couple days.


If you don't want to buy the Celestron GPS unit for the mount, I was wondering if one of the hand-held GPS, like a Garmin, would do. I've never used on personally. I know they let you store waypoints, but I don't know if they give you a real-time readout of your location.

#7 SanDiegoPaul

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Posted 09 February 2010 - 07:09 PM

I have a Garmin and those are the coordinates that I will be entering. I need to figure out how though.

#8 drksky

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Posted 09 February 2010 - 08:59 PM

That's what I wasn't sure about. Do the hand-held Garmin's give you a real-time coordinate readout?

#9 neptun2

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Posted 09 February 2010 - 09:58 PM

About Garmin - yes coordinates are updated in real-time. About the latitude and longitude change - here is what i found in cgem manual on page 19:

Updating Your Location - Since you may not need to update your observing location as often as the date and time, it
is not displayed each time you update the date and time. To update your city, press UNDO at any time when updating
your date and time. Continue to press UNDO to change the state, country or to add longitude/latitude coordinates.

#10 Fred1

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Posted 09 February 2010 - 09:59 PM

I have a Garmin and those are the coordinates that I will be entering. I need to figure out how though.


It's pretty simple actually. When you are setting up, scroll to "Custom Site". Then input your coords. They'll be saved until you change them or reestablish the "factory settings."

#11 gatsbyiv

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Posted 10 February 2010 - 12:17 PM

Every time I try to replace an alignment star after polar aligning, it gives me trouble. It lets me replace the first star fine, but causes trouble when I try to replace the second. Maybe I'm missing something (only second night out with the mount), but I just turn it off and back on, then align as normal and everyone is happy.

A recent "dialog" between me and the HC after polar alignment recently was something like:

HC: "Replace Caph?"
Me: <selects Yes>
HC: "Slew to Hamal."
Me: "What? No! I already replaced Hamal."
Me: <presses Undo, then Alignment Stars again>
HC: "Replace Caph?"
Me: <selects Yes>
HC: "Slew to Hamal."
Me: "Grrr..." <Slews to Caph anyway.>
HC: "Slew to Hamal."
Me: <reboots>

What am I missing?

#12 Fred1

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Posted 10 February 2010 - 02:08 PM

I'm not sure what I'M missing here. What alignment stars did you use and what calibration stars did you use when you got the above dialogue?

Also, why are you replacing alignment stars?

When during the course of the evening are you replacing an alignment star?

PS: Also, see page 38 of the CGEM Manual "Updating your Star Alignment." Note that you should slew the telescope to one of the original alignment stars.

#13 freestar8n

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Posted 10 February 2010 - 02:15 PM

The mount should be polar aligned and ready for GoTo's right after the polar alignment procedure. If you do want to refine the alignment, try to avoid shutting down because that will lose accuracy in the previous calibration.

If you want to replace alignment stars, you should go to the new star first, and then use Align/Replace. It should then ask you to make sure you are centered on the desired (current) star.

(There is a trick/subtlety. You don't even have to go to the star first - just go down the list of named stars and stop on the one you want. Then go to the align menu and it will ask to go to the star you just selected in the list. It's the list that determines what star you align and center on - if this makes sense).

Frank

#14 SanDiegoPaul

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Posted 10 February 2010 - 02:45 PM


It's pretty simple actually. When you are setting up, scroll to "Custom Site". Then input your coords. They'll be saved until you change them or reestablish the "factory settings."


Nope the Custom Site menu never appears. That is what I am trying to find.

#15 SanDiegoPaul

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Posted 10 February 2010 - 02:47 PM

Every time I try to replace an alignment star after polar aligning, it gives me trouble. It lets me replace the first star fine, but causes trouble when I try to replace the second. Maybe I'm missing something (only second night out with the mount), but I just turn it off and back on, then align as normal and everyone is happy.

A recent "dialog" between me and the HC after polar alignment recently was something like:

HC: "Replace Caph?"
Me: <selects Yes>
HC: "Slew to Hamal."
Me: "What? No! I already replaced Hamal."
Me: <presses Undo, then Alignment Stars again>
HC: "Replace Caph?"
Me: <selects Yes>
HC: "Slew to Hamal."
Me: "Grrr..." <Slews to Caph anyway.>
HC: "Slew to Hamal."
Me: <reboots>

What am I missing?


That is exactly my problem too. The software may have a LOT of other nice attributes, but this particular area stinks. Once you have done your Polar Align and undone your Sync, it should go right into another All-Star alignment.

I hope a future patch fixes this.

#16 SanDiegoPaul

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Posted 10 February 2010 - 02:48 PM


Also, why are you replacing alignment stars?

When during the course of the evening are you replacing an alignment star?


That is the option it brings us to, after we undo the Sync and want to do another All Star Alignment (after the Polar is done)

#17 freestar8n

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Posted 10 February 2010 - 03:35 PM

I hope a future patch fixes this.



No patch needed. See my explanation above. Go to the star first, then ask to replace it. It is trying to slew to Hamal because that is the last star that was selected in the named star list, and it thinks that's the one you want.

The reason that it is not going to a new alignment directly is that AllStar is designed so that your mount is already polar aligned and ready for GoTo's - WITHOUT a new alignment. But if you WANT to realign, for whatever reason, you can using the normal procedure of going to a star and asking to use it for replacement.

Frank

#18 Fred1

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Posted 10 February 2010 - 07:01 PM



It's pretty simple actually. When you are setting up, scroll to "Custom Site". Then input your coords. They'll be saved until you change them or reestablish the "factory settings."


Nope the Custom Site menu never appears. That is what I am trying to find.


"Custom Site" comes right after "City Database." Don't press ENTER when "City Database" appears, just scroll again and it will be there. Then press ENTER and follow the prompts.

#19 David Pavlich

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Posted 10 February 2010 - 10:34 PM

Question for the new Celestron mount owners: The "old" CGE PA routine was a 2/4 star alignment, then the PA routine. When the PA routine was complete, the CGE would go back to the Switch mode...basically finding home position again. Then you'd do another 2/4 star align and it's off to the races.

So...does the new All Star PA routine eliminate the need to start from the beginning once the PA routine is done? I ask because when you do the PA routine, the mount has changed positions because the Alt and Az posititons have changed.

And another query...would it be easier if once the PA routine was completed, shut the mount off and place everything in the home postition, then do the star alignments?

Thanks! David

#20 freestar8n

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Posted 10 February 2010 - 11:10 PM

A big benefit of AllStar is that it avoids the need to find the switches - which is a process that loses some calibration accuracy. It also compensates for the alt/az motions of the polar alignment.

So - you do align on two stars, then add some calibration stars, then do the polar alignment routine and adjust the mount. Then - you are done and ready to go with good goto accuracy - assuming you did the PA routine correctly.

If for whatever reason you do want to realign on two stars, you can - usually by replacing the two original stars with themselves - but it could be any two decent stars.

No reason to shut the mount down and lose accuracy by re-finding the switches. Just do the PA, then observe. Much faster than having the mount go back home and start all over.

Frank

#21 Fred1

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Posted 11 February 2010 - 12:11 AM

Frank is right. Celestron has come up with a great program for Polar Alignment. Note that the $5000 CGE Pro has no accommodation for a polar axis scope. The Celestron rep at an expo I was at in October told me it was because the PA program is so accurate it negates the polar axis scope altogether. Also, I've read that the CGEM will be the last Celestron mount to have a bore hole for the polar axis scope option.

#22 David Pavlich

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Posted 11 February 2010 - 09:18 AM

Thanks, Frank! I wondered if the mount compensated for the adjusments made when polar aligning.

David

#23 gatsbyiv

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Posted 11 February 2010 - 09:16 PM

Interesting. Thanks, Frank. I was just following the manual instructions, which state to Undo Sync, then replace the alignment stars after Polar Align. But if I don't have to do this, well then, that is that much more time inside (where it is warm)!

Also, I figured out my Caph/Hamal problem described above. I was *manually* slewing over to the next star I wanted to replace. If I ask the mount to do the slewing by selecting the star from the Named Star list, the replacement works fine. Frankly, it's faster for me to manually slew, but it looks like the whole step is unnecessary anyway.

#24 freestar8n

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Posted 11 February 2010 - 11:21 PM

Hi-

I just re-read the cgem manual to see how they describe it. They say:

"After polar alignment it's a good idea to check the pointing accuracy of the telescope to see how much it may have been affected by moving the mount. Since the polar alignment process requires you to "sync" the telescope on a bright star before you begin, it will be necessary to undo the sync before re-aligning."

This is somewhat loaded, but it says you MAY need to re-align, but check the goto accuracy and see if it is needed. Although the mount does move during polar alignment, as long as the mount moves as it should to polar align, the GoTo accuracy should still be ok.

So - I'd just do the polar alignment carefully and then see how good the GoTo is. If it is accurate near the polar alignment star, but it gets worse farther away, try unsyncing. If it is still bad, try replacing 1 or 2 alignment stars.

So - mainly I'd say just to try things and see what is needed for your mount. But make sure the mount is calibrated before you do the All-Star, or the polar alignment won't be as accurate as it could be, and the pointing accuracy immediately after the polar align also won't be as good as it could be.

Frank

#25 David Pavlich

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Posted 12 February 2010 - 09:21 AM

Hi-

This is somewhat loaded, but it says you MAY need to re-align, but check the goto accuracy and see if it is needed. Although the mount does move during polar alignment, as long as the mount moves as it should to polar align, the GoTo accuracy should still be ok.

Frank


This is the part that puzzles me, especially if you're using an SC. With its narrow FOV, even a little bit of movement of the Alt and Az adjustments will move an object out of the FOV. I don't know how the gotos would be accurate unless you were lucky enough to have everything polar aligned before you started the PA routine.

That's why I asked the question earlier. If this is the case, then the mount doesn't compensate for the manual movement in Alt/Az. Or am I missing something?

David






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