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Ode to the CG-5GT

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#26 Starhawk

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Posted 22 April 2009 - 12:28 AM

Rod,

The scope has GPS, so I have been using the data directly. After alignment, I have gone into the Polaris alignment, and the distance to Polaris is huge- where I have put the tripod down with the wedge roughly in alignment, I will be moving it all the way to one end of its range to get Polaris centered. And at this point, realigning isn't the issue- there is massive drift. If I take images, stars swirl in the frame showing the scope is way off in polar alignment. So, starting over from scratch, the mount will be very, very far from where a drift alignment indicates north is. I have found one shortcut to get close after the Nexstar polar alignement anomaly- when the mount starts with the tube lined up with the marker pointed at the meridian, the first guess it makes at a star is a fair approximation of a true polar alignment, so manually moving back from the polar misalignment can be done by centering without using the motors. From there, a conventional polar drift alignment works.

If there is something I am doing wrong, I don't know what it is. Other than this behavior, the mount seems to function perfectly. I'm getting ready for some observing on top of Mt. Lemmon, so I'll try this again this weekend and see if there is some way to do this where it works. If you've seen one of these do it, then I'll try again. I'll write back if I can figure out what the problem is.

-Rich


OK, I'll bite- what's so special about All Star Polar Alignment? I'm still a bit annoyed by the disasterous Nexstar polar alignment where it was supposed to get an alignment on Polaris, but in fact resulted in being several degrees from true alignment, but y'all seem to think this is as good as a drift alignment. Can someone please describe what happens?

-Rich


The advantage is that you can use any star (away from the horizon) to perform the polar alignment, not just Polaris.

If the original polar alignment utility is producing alignments "several degrees" off, then I gotta say "prob'ly pilot error," as I've used it for years with good success:

1. Remember, once you start the polar align procedure, you do NOT move the scope in declination or RA. You center Polaris using _only_ the mount altitude and azimuth adjusters. IOW, follow the on-screen prompts.

2. Naturally lat/lon, date, time-zone, DST must all be correct in the HC.

3. Remember to redo the go-to alignment following the polar alignment procedure. Early mounts needed to have their power cycled following polar alignment.



#27 Qkslvr

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Posted 22 April 2009 - 02:00 PM

I've found the All Star Polar align not as good as a drift alignment. But my goto's and waking up from hibernation are great, I can wake it up, go to an alignment star, and find it in the liveview box most times!

#28 rmollise

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Posted 22 April 2009 - 05:06 PM

I've found the All Star Polar align not as good as a drift alignment. But my goto's and waking up from hibernation are great, I can wake it up, go to an alignment star, and find it in the liveview box most times!


I don't think anyone would claim it is as good as a drift alignment, and it is much quicker. It's also more than useable for the kind of imaging most folks are doing: stacking multiple 5 minute or less subframes.

#29 rmollise

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Posted 22 April 2009 - 05:08 PM

Rod,

The scope has GPS, so I have been using the data directly. After alignment, I have gone into the Polaris alignment,


Not sure what you are doin' bro. Before you do anythin' else, you sight Polaris through the hollow RA axis, then proceed to go-to alignment and then polar alignment. If the mount is pointing somewhere other than close to north when the go-to stops after you start the polar alignment, you have go-to problems.

Which version of the firmware do you have loaded? I do seem to recall there was a Polaris problem with one of the early ones. If you don't have a fairly recent load, upgrade. If you don't have an upgradeable HC, there is always NexRemote.

#30 Starhawk

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Posted 22 April 2009 - 11:46 PM

I did some more reading. As it turns out, I have been using an old controller, and it's one which screws up the alignment. Apparently I am in luck, and I can get a new HC directly from Starizona, which is just across town. So, I can get this funky new alignment method, which if it works reasonably well, will at least get in the immediate vicinity for a drift alignment.

Thanks for your help, though. Looks like I am getting a spare HC for use in case of emergency.

-Rich

Rod,

The scope has GPS, so I have been using the data directly. After alignment, I have gone into the Polaris alignment,


Not sure what you are doin' bro. Before you do anythin' else, you sight Polaris through the hollow RA axis, then proceed to go-to alignment and then polar alignment. If the mount is pointing somewhere other than close to north when the go-to stops after you start the polar alignment, you have go-to problems.

Which version of the firmware do you have loaded? I do seem to recall there was a Polaris problem with one of the early ones. If you don't have a fairly recent load, upgrade. If you don't have an upgradeable HC, there is always NexRemote.



#31 Jim Romanski

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Posted 07 May 2009 - 09:49 AM

Thanks Mark

And Thanks Rod for the links. I went to the Celestron website and got the file but I was at a loss for how to connect my hand controller to a serial connector. I know I have some old serial cables hanging around but the connector at the bottom of the hand controller is a phone connector. Now I see what I have to get.


You'll need to buy or make a serial cable for the Celestron. Go on back to Mike Swanson's Nexstarsite.com for instructions if "build" sounds good.

;)

I bought the actual Celestron cable off of Amazon (though sold by Adorama) for $17. It's called the Celestron Nexstar RS 232 PC Interface Cable part #93920. You can use it to update the controller and to control your scope with some software.

I updated my hand controller and the motor drive software last night. Thank's Uncle Rod for the info. It worked like a charm.

Of course it's been cloudy and rainy for so long that I'm still waiting to test it out.






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