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old_eyes

Final step in aligning a CG5-GT?

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Last night I was out testing my newly acquired second-hand Atik 16ic, and so tried to carefully polar-align the CG5-GT.

For the first time I actually felt it worked the way it was supposed to. I roughly lined up the tripod looking at Polaris through the scope with both axes set to their index marks. Then used the polarscope to refine. Then powered up the mount and did a two star align.

Next I used the polar-align routine to adjust the ALT-AZ on the mount. When I hve tried previously, I was so far away from polar alignment that there wasn't enough travel in azimuth to get it properly aligned. This time I was able to bring the target star smoothly into the centre of the eyepiece. Great! Very happy!

However, by moving the mount I have disrupted the sky alignment, so the go-to would be off. If I went back to the two star-alignment it only offered me the chance of replacing the original calibration stars, when what I think I want to do is a fresh alignment with a now properly polar-aligned scope.

The polar alignment was probably best I have ever got, as targets in the sensor FOV barely moved over 10 minutes at f=1500mm. The pointing was just a bit off, which made acquiring a target for the CCD a bit tricky. I had to use an eyepiece to centre after the go-to, and then put the camera on and re-focus.

This must be a problem that others have solved, and I can't see the blindingly obvious. What's the best way to get good go-to alignment after using the Celestron polar align process?

old_eyes

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Well, 1st things 1st, Don't ask me about drift alignment, never used it or tried it. Just make sure the mount is flat & the bubble is centred in the bubble level indicator. Make sure everything is balanced. When using alignment with Goto, I tend to do a 3 star alignment, my 1st star is usually to the south at the moment - Zosma, I always try to find stars that are quite high in the sky especially in the southern direction, 2nd is Capella & 3rd is Dubhe. If you want to align with more then 3 stars, you might want invest in something called EQMOD (but im not sure if it would work on a CG5-GT), this allows your mount to be controlled by a Star Chart Software eg. TheSky6, StarryNight, thus giving you the flexibilty of a 4 or 5 star alignment for accuracy, plus not bothering to enter your co-ordinates, time & date everytime you use it. But due to the weather not had the chance to try mine out yet... HTH

Cheers

Nadeem.

Edited by Deneb

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Well, 1st things 1st, Don't ask me about drift alignment, never used it or tried it. Just make sure the mount is flat & the bubble is centred in the bubble level indicator. Make sure everything is balanced. When using alignment with Goto, I tend to do a 3 star alignment, my 1st star is usually to the south at the moment - Zosma, I always try to find stars that are quite high in the sky especially in the southern direction, 2nd is Capella & 3rd is Dubhe. If you want to align with more then 3 stars, you might want invest in something called EQMOD (but im not sure if it would work on a CG5-GT), this allows your mount to be controlled by a Star Chart Software eg. TheSky6, StarryNight, thus giving you the flexibilty of a 4 or 5 star alignment for accuracy, plus not bothering to enter your co-ordinates, time & date everytime you use it. But due to the weather not had the chance to try mine out yet... HTH

Cheers

Nadeem.

Nadeem - thanks for the advice. I am definitely trying to avoid drift alignment for the moment as I am setting up and knocking down my rig each session. Like the idea of using EQMOD or some equivalent and am looking into it. That would make life easier.

On the selection of stars I used Capella and Dubhe, and I 've forgotten the third.

However, in the meantime, just trying to understand what to do after using the Celestron polar-align facility to get the go-to accurate. I suppose I could turn the mount off and on and then re-do the initial alignment. That would give me a fresh alignment without affecting the polar-alignment.

Are you using a CG5? I think this partiuclar polar-align process is specific to that mount.

old_eyes

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I used to have a CG5 mount, the electronics between the EQ5,CG5 & EQ6 are the same really.

Nadeem...

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I have never done the full polar aligment on myc CG5 that you have old_eyes - but by my recollection the manual does say that you have to do a full sky alignment again after the polar align routine.

Strictly speaking I think that replacing the two alignment stars ought to work but I would be inclined to think that the whole schbang is the way to go as implied by the manual.

At the moment I am strictly visual so it isnt really necessary for me to do anything other than plonk the thing down roughly facing north and more or less level, though I do sight Polaris through the boresight and get the bubble in the circle which is usually easy enough (I have marks on the tripod extenders to get the length right for my usual obs position). I usually always take all four calibration stars too (it helps me learn and remember the sky lol)

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I used to have a CG5 mount, the electronics between the EQ5,CG5 & EQ6 are the same really.

Nadeem...

I'll check out EQMOD then. It looks a much simpler way to go.

old_eyes

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I have never done the full polar aligment on myc CG5 that you have old_eyes - but by my recollection the manual does say that you have to do a full sky alignment again after the polar align routine.

Strictly speaking I think that replacing the two alignment stars ought to work but I would be inclined to think that the whole schbang is the way to go as implied by the manual.

That's what I read, but I couldn't seem to force it to do a fresh sky alignment. Next time I'll try replacing all the alignment stars and seeing if that helps.

I am with you on visual. I use the Nexstar mount for that. Roughly level, line up on three bright stars and you're good to go. Definitely less demanding and a lot quicker :)

old_eyes

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Just kill the power and start again? - The polar alignment is mechanical so it will hold through the power off and when you power up it will be nicely polar aligned and automatically drop into the start up and 2-star alignment procedure no?

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For my CG5 I firstly do 2 star, then polar align.

Tutn off/on & reset to markers.

Then 2 star + 3 calib stars. (Capella, Procyon, Dubhe, Regulus & Phad) The goto works quite well after that, wish i could say the same for my DEC tracking tho.

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For my CG5 I firstly do 2 star, then polar align.

Tutn off/on & reset to markers.

Then 2 star + 3 calib stars. (Capella, Procyon, Dubhe, Regulus & Phad) The goto works quite well after that, wish i could say the same for my DEC tracking tho.

Thanks. That was exactly what I was lookin for. You turn off and on and then do the sky align from scratch. I'll try that.

old_eyes

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Firstly, don't trust the bubble level on the mount. The one on my brand new CG5 GT is miles out, use a seperate level.

The users manual is downloadable from Celestrons site and it does tell you about the polar align routine.

Finally, after doing the 2 star align, add as many calibration stars as you can to improve the pointing accuracy.

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Newer firmware allows to do drift aligment on any star after initial aligment.

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Yeah, i forgot to mention that I had the same idea as yourself with just going back into the menus and changing the alignment stars - but it wont let you for some odd reason. Thats why I power off and go from scratch again, and after your first alignment star is done most other stars that follow are already in (or just in) your EP, so no need to faff about with the finderscope.

The whole thing should take no more than 20min tops.

Oh, and like the man says above - get your own spirit level on the case :)

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Hey old_eyes, after you do the polar alignment routine you can either replace 1, 2 or 3 of the 'alignment' stars or completely power the mount down and carry out the goto alignment again. You dont have to touch the alt or azi screws again unless you move the mount and / or tripod. The instruction manual is a bit vague in this respect but read through it a few times and it'll become clear.

As for EQMOD, as for as I know there isn't a version available for the Celestron mounts, which is a pitty as EQMOD is very good.

HTH,

Gary

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Does the Celestron software allow you to refine your alignment once its done? EQ and Meade software does this, so for imaging you might ask it to go to a star near your target, re-centre on that and then make the short hop to your target. I have done this once or twice when trying to image some infernally faint thing invisible even in 30 second bin 2 exposures.

Olly

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Does the Celestron software allow you to refine your alignment once its done? EQ and Meade software does this, so for imaging you might ask it to go to a star near your target, re-centre on that and then make the short hop to your target. I have done this once or twice when trying to image some infernally faint thing invisible even in 30 second bin 2 exposures.

Olly

Dear Olly,

There is a sync facility on the CG5 that allows you to 'reference' a star close to your target and is supposed to give more accurate results for that area of the sky. Sounds like the same thing you are talking about. Haven't used it yet, as so far my imaging has not yet reached the stage where that kind of accuracy is the limiting factor :).

This is some of the stuff Ihope to learn when I am with you at Les Granges in June :p.

old_eyes

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Dear Olly,

There is a sync facility on the CG5 that allows you to 'reference' a star close to your target and is supposed to give more accurate results for that area of the sky. Sounds like the same thing you are talking about. Haven't used it yet, as so far my imaging has not yet reached the stage where that kind of accuracy is the limiting factor :).

This is some of the stuff Ihope to learn when I am with you at Les Granges in June :p.

old_eyes

Uh-Oh, then you'll find out what an inept old buffer I really am!!

Olly

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Uh-Oh, then you'll find out what an inept old buffer I really am!!

Olly

Bufferishness is relative :)

old_eyes

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Newer firmware allows to do drift aligment on any star after initial aligment.

Is that new firmware for the CG5-GT? I thought I had the latest version. Where is the drift alignment hidden in the menu?

Not that I am ready to go anywhere near drift alignment yet :). Let me get the basics first!

old_eyes

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As for EQMOD, as for as I know there isn't a version available for the Celestron mounts, which is a pitty as EQMOD is very good.

HTH,

Gary

That was my understanding also Gary, but i was interested in case there was one. People speak highly of EQMOD and there are lots of people on SGL with deep skills.

I am told that CG5-GT mounts can be computer operated by a range of software. Do you know which packages support this mount?

old_eyes

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That was my understanding also Gary, but i was interested in case there was one. People speak highly of EQMOD and there are lots of people on SGL with deep skills.

I am told that CG5-GT mounts can be computer operated by a range of software. Do you know which packages support this mount?

old_eyes

Most palnetarium software will control a mount, to a greater or lesser degree. Start off by downloading ASCOM Driver for the Celestron mount. There is 2 parts to this, I will send a link to them later as I am at work just now. Google ASCOM Drivers, it should be apparent what you need and they are free.

Then, if you are looking for a free package then get Stellarium. If yuo want to pay then get Starry Night Pro, thats what I use.

The planetarium will comunicate to the mount through ASCOM.

Let me know if you want the links mate.

Gary

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Let me know if you want the links mate.

Gary

Thanks Gary - I found the links easily enough. All that I need now is the time to learn all this :).

old_eyes

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