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CGEM alignment anomaly

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#1 Lane

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Posted 17 July 2009 - 02:38 AM

Been using my CGEM for several months now without any problems at all. Wednesday night however, something strange happened. I set the mount up as usual and started the alignment process. Picked the 1st star and pressed enter. Normally if I have the mount level and aimed pretty close to polaris then after pressing enter the scope will put the first alignment star in a 40mm eyepiece. Then I just center it and go to the next alignment star. This night, the first star selected was Arcturus but the scope pointed somewhere near the tail of scorpius, which is a long way from Arcturus. So I used the arrow buttons to move it all the way back over to Arcturus and went the next alignment star, Mizar in the big dipper. This time when I pressed enter it pointed due east and below the horizon. So I used the arrow buttons again and put it on Mizar. Same problem with the first calibration star. I picked Antares in Scorpius and it pointed to Cassiopea. Again I moved it and centered Antares. Then it calibrated for a few seconds as usual and said alignment successful. I then tested the GOTO operation by selecting object M13. It put it dead center of the eyepiece. So the alignment worked but the routine that finds the initial stars went seriously haywire. Later in the evening I bumped into the scope and needed to turn it off and realign everything. This time it worked perfect and put every alignment star in the eyepiece requiring only a little movement to get them centered. I am really curious about what could have caused this since I did not change anything except the time and date as usual during the setup. Has anyone else had this happen to them?

#2 Luigi

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Posted 17 July 2009 - 06:06 AM

I don't have a CGEM but assuming it works like a CG5, did you have the startup RA and Dec alignment ticks lined up when you initialized the mount?

#3 Lane

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Posted 17 July 2009 - 12:15 PM

Yep - nothing I haven't done dozens of times before. I guess it is no big deal since it aligned properly in the end, but I am still really curious to know what caused it or if it ever happened to anyone else.

#4 Kolenka

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Posted 17 July 2009 - 02:02 PM

I'd just double check that the date/time was not reset by something. I've had the CGE reset on me without me realizing it and get the exact same behavior.

#5 Lane

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Posted 17 July 2009 - 03:36 PM

On the CGEM you have to enter the date and time when you power up the scope. It does not have an internal battery like my old LX200 did.

And actually I left out part of my story, because when it first went to the wrong location I turned it off and pulled the power cord then tried it again and again and again. I re-input all the site information several times. Nothing worked, so after a frustrating 30 minutes I decided to just center the alignment stars and see what would happen. Happlily it aligned and I did not waste a trip up to the dark site. I was pretty angry at first after driving 1hr and 40 minutes to the dark site to have it mess up like that. But the lack of dew that night and the extra dark sky made up for it. The best viewing night I have had in the last year.

#6 freestar8n

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Posted 17 July 2009 - 05:58 PM

Hi-

I have a cge, and weird things can sometimes happen if an alignment star is near the meridian. That may have been the case with Arcturus this time of year. Anyway - something to be aware of - and to avoid if possible. The mount tries to overshoot the star and come back to correct for backlash - and sometimes it has trouble on a star near the meridian. Not sure that's the issue here, but it might be.

Frank

#7 rmollise

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Posted 17 July 2009 - 07:18 PM

Has anyone else had this happen to them?


Yep, shore have, pard. The fault? Me, not the mount. Invariably, I'll find I've entered time or date incorrectly. Yeah, yeah, I know...I've been sure _I've_ entered it right, too. ;)

BTW, don't spend a lot of time leveling the mount...it's not necessary.

#8 Blixx

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Posted 17 July 2009 - 08:01 PM

With my cgem, I hardly ever get my first star in the field of view. Once I do though, the rest of the stars are in the fov of my 25mm ep every time.
Dan

#9 Hank w

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Posted 17 July 2009 - 08:34 PM

Hi Lane: Above you mentioned that you have to enter the time and date every time you power up your CGEM mount. I have not used my CGEM for several days and just now powered it up. The time was maybe 1 or 2 seconds off and the date was perfect. I can not say I've had to set the time over the last 2 months. I have occasionally received the no response 17 error, possibly due to momentary disconnect when a cable was incorrectly stretched. I could then hit the "rate "and or the "undue" button and continue to observe with no interruption in alignment.
Hank

Hank

#10 Blixx

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Posted 18 July 2009 - 05:23 PM

I must agree with Hank. I have not had to set the date or time on my cgem. I put the date time in the first time I fired it up but that's it.
Dan

#11 Lane

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Posted 19 July 2009 - 02:51 AM

That is very interesting, whenever I turn on my CGEM the date and time are always the date and time from the last time I turned the scope off. There must be a battery inside the hand controller and mine must be dead. I will contact celestron support and see what's up with this.

The anomaly has not repeated itself, it worked later that night and it worked correctly last night too.

#12 Lane

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Posted 19 July 2009 - 03:31 AM

Has anyone else had this happen to them?


Yep, shore have, pard. The fault? Me, not the mount. Invariably, I'll find I've entered time or date incorrectly. Yeah, yeah, I know...I've been sure _I've_ entered it right, too. ;)

BTW, don't spend a lot of time leveling the mount...it's not necessary.


I have done some dumb things in the past, I don't deny that, but this one was definitely not me. This thing was all over the place. I would have thought that after I centered the first alignement star that it would have found the next one, but it missed the second by at least 50 degrees. I could not see any pattern to what it was doing, it just seemed to randomly go to various areas of the sky. But the problem has not repeated itself so I am not going to worry about it.

I am concerned about that clock issue though. That has been an annoying thing since I got the mount. Always having to enter the time and date everytime I power up, I wondered why they did not implement a clock inside the hand controller. It never even crossed my mind that there was a problem. But based on the responses in here it sounds like there is a battery and a clock in there. I just shot a message off the celestron support, hopefully it is just a matter of me replacing a battery and I won't have to send them my hand controller.

I also noticed something else last night, I put in 2 alignment stars and 2 calibration stars. One more calibration star than I usually use. With those 4 stars it stayed on target for my entire viewing session and put every single object within about 10 arc minutes of the center of view. So I was able to leave a 14mm Pentax in the scope during GOTOs and the object was always somewhere in the eyepiece. In fact, half of the objects were dead center of the eyepiece. I did not realize that one extra star would have such a big impact. I think I will try a total of 5 stars during alignment next time and just see if it improves even more.

#13 jrcrilly

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Posted 19 July 2009 - 07:39 AM

That is very interesting, whenever I turn on my CGEM the date and time are always the date and time from the last time I turned the scope off. There must be a battery inside the hand controller and mine must be dead.


I believe that the clock is in the telescope base of the models so equipped. There's an option to turn it on and off; yours may be turned off.

#14 waassaabee

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Posted 19 July 2009 - 08:25 AM

That is very interesting, whenever I turn on my CGEM the date and time are always the date and time from the last time I turned the scope off. There must be a battery inside the hand controller and mine must be dead.


I believe that the clock is in the telescope base of the models so equipped. There's an option to turn it on and off; yours may be turned off.


Lane, Make sure RTC (Real Time Clock) is ON.

#15 donsinger1

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Posted 19 July 2009 - 10:06 AM

With my cgem, I hardly ever get my first star in the field of view. Once I do though, the rest of the stars are in the fov of my 25mm ep every time.
Dan


Same with mine. It is a great value.

#16 Lane

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Posted 19 July 2009 - 06:53 PM

Gary - Thank You so much :bow: :bow: :bow:

My clock is active and working now, I guess this means there is a battery in the mount just like in my old LX200. Must be behind the control panel.

I only read the manual once, probably should have read it more than that because I missed that little explanation on page 29 about the RTC. When I saw RTC after GPS in the Utility menu of my hand cotroller I thought it was part of the GPS settings so I just ignored it and never realized it meant Real Time Clock :foreheadslap:

#17 waassaabee

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Posted 20 July 2009 - 10:02 AM

Hey Lane, your welcome and no problem!! If you are going to be using planetarium software for driving the scope, you can turn RTC=OFF and the mount will read the laptops clock.
I guess I'm a bit anal about product documentation as with the CGEM I had read the manual three or four times before I received the mount. From that I'd made myself somewhat a checklist of things to watch, and test. After a half dozen nights out with the mount I'm very comfortable with it's operation, and consider it the best investment I've made thus far in astro gear.

#18 birdleggs

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Posted 21 July 2009 - 11:16 AM

I had the same problem (alignment stars being way off). It happened a couple of nights in a row. Cycling the power didn't help, and I checked, and re-checked the time/date/location/DST, but everything was correct. I finally did a factory reset, and it cured the problem. By the way, the battery is in the mount, behind the panel.

Mike.

#19 Lane

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Posted 21 July 2009 - 05:26 PM

That is what I was trying to do originally, but could never find the factory reset instructions in the manual.

#20 waassaabee

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Posted 22 July 2009 - 04:18 PM

There are a couple of pages in the manual that graphically layout all of the hand controller menu items. I have these in a page protector for quick reference.

#21 Lane

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Posted 22 July 2009 - 04:40 PM

What is the reset procedure?

#22 waassaabee

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Posted 22 July 2009 - 05:10 PM

Menu>Utilities>Factory Settings>
Ref. Page 29 in the CGEM Manual for details.

#23 Lane

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Posted 22 July 2009 - 06:00 PM

Thanks, if it ever messes up again I will give that a try to see it corrects the issue. So far so good though, no repeat of the issue.

#24 waassaabee

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Posted 22 July 2009 - 07:26 PM

The factory reset is a last ditch effort in my opinion. Even though you can have the settings it wipes out redone in a night, it's still a PITA!!






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