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Stupid questions on the Celestron Advanced GT mount

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#1 DanMiller

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Posted 02 December 2022 - 10:43 AM

i kind of feel stupid asking this, but with clear nights being crap shoot which I was never good at.  Might as well look stupid.

 

Previously this summer, I purchased a used Advanced GT mount. I have it set up, have reset the hand set which is the origional handset I beleive. I have finally just received what I think I need to attach my camera to the mount.  No questions about that.

 

You must unnderstand, that my previous experience with any type of mount was the Star Adventurer 2i Pro which is out of action till I feell like taking the time to try and fix.  But, everything I did with this mount was pretty much manually done.  Wit that said, here goes.

 

 

After I do the star alignment, which I should be able to do with I will enter into the mount my target then use the handset to fine tune the framing from there.  Do I turn on the tracking at that point? Or after I have completly framed the target.   I am assuming that I should start tracking after I have done the three star alignment, but I would rather be sure.

 

also, I have read here you can set boundries that you can set on these type of mounts so that it will stop tracking after it reaches a certange degree setting(meridian point?).  Nowhere do I see that in the manual.  Shoot, I don't even see in the instructions on how to do a meridian flip.  Which I have never done before.

 

My plan is to use M31 to start with, just because it is an easier target and is easy to verify I have framed in test images.

 

Any general help like this would be most helpful.



#2 wrvond

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Posted 02 December 2022 - 11:59 AM

Do the most accurate polar alignment you possibly can.

Do the most accurate two or three star alignment you possibly can.

In theory, the more stars you align on, the more accurate the GoTo and tracking.

Perform GoTo function. Your target should be dead center.

Tracking starts automatically once the scope has stopped on the target.

 

If you don't have a Next Star + hand control, I suggest you get one and update the HC and MC drivers. 

In the back of your manual is a command tree that lists all the menu items and the path to get to each. Limits are set in the mount settings menu IIRC.

 

You might want to investigate obtaining a small guide scope, you'll find the tracking much more accurate than anything the CG-5 can do on it's own.



#3 vtornado

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Posted 02 December 2022 - 12:09 PM

I am a beginner too, and my Andromeda is  not so good.

I am using a 130mm f/5 newt, .5x focal reducer and 178MM camera.  I am stacking

15 second frames, which is about all I can get without trailing.

 

The core is beautiful, but the rest of it is lost in light pollution.  I'm in Bortle 8.  I know I can get it better, but it is going to take more work, not just turn the camera on and go.

 

M43 (orion neb) you can use filtering   M43 is rising, so it is awhile before you have to worry about any meridian flip.

 

I know you have to learn these eventually, but there is enough to learn just with M43.


Edited by vtornado, 02 December 2022 - 01:12 PM.


#4 DanMiller

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Posted 02 December 2022 - 12:30 PM

Do the most accurate polar alignment you possibly can.

Do the most accurate two or three star alignment you possibly can.

In theory, the more stars you align on, the more accurate the GoTo and tracking.

Perform GoTo function. Your target should be dead center.

Tracking starts automatically once the scope has stopped on the target.

 

If you don't have a Next Star + hand control, I suggest you get one and update the HC and MC drivers. 

In the back of your manual is a command tree that lists all the menu items and the path to get to each. Limits are set in the mount settings menu IIRC.

 

You might want to investigate obtaining a small guide scope, you'll find the tracking much more accurate than anything the CG-5 can do on it's own.

I have a guide scope on my dslr camera.  Have used it before for guiding.



#5 TelescopeGreg

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Posted 02 December 2022 - 01:05 PM

The sequence is to do a polar alignment first - it's a mechanical alignment of the mount to the Earth's axis using the Azimuth and Elevation knobs on the mount.  Pointing it at Polaris will get you in the ballpark.  Does your AVX have a Polar Alignment Scope inserted into the RA axis?  It's an option that makes polar alignment a lot easier, but there are other methods.  Don't fiddle with the mechanical adjustments once they're done.

 

Once you have the polar alignment you should do a Star alignment.  This is a software calibration step that tells the NexStar controller where things are in the sky, so that the GoTo functions properly.  The hand controller has a built-in database of stars that it likes to use for this (the 1-star and 2-star alignments), or you can use "Quick Align" and pick your own stars.  It depends on how familiar you are with the sky and what you can see.  The built-in alignment process kept asking for stars I couldn't see, so I always used Quick Align.  I would pick a pair of stars that I could identify, one on either side of the Meridian, to align on.  Go to them, use the arrow keys to center the star in the eyepiece (a reticle eyepiece is extremely handy for this), then press Align and Ok a few times.  For added accuracy you can add a pair of Calibration stars; same process but after pushing Align use the scroll up/down keys (6 & 9) to choose Calibration instead of Alignment.

 

For both Polar and Star alignments, the more precise you can do them the better.  This is a hobby where really small errors make a really big difference.


Edited by TelescopeGreg, 02 December 2022 - 01:06 PM.

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#6 MaxUll

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Posted 03 December 2022 - 02:04 PM

I've had an advanced GT that I started doing astrophotography with. The mount works but can give you some troubles compared to more modern mounts.

First of, the mount should start tracking right after you finished the initial set up, location/time/etc. If not there's an option for this in the hand controller (under "scope set up" if I remember correctly).
Before that you should have roughly pointed it correctly to the north/south.
A common and proved teqnique to get good go-to is to first do a 2+4 star alignment. Then follow up with the ASPA, "all star polar alignment", you can find this option in the hand controller as long as it isn't too old (first edition old I believe).
After the polar alignment you should power the mount off and re-do the same steps as above one more time. This often corrects the most of the pointing error and gives you a better polar alignment.

With the ASPA you don't need any polarscope but use your telescope instead, much like sharpcap/Nina does.

A few other things to remember. Always finish your corrections with the up and right arrow key, this meshes the gears the right way. Always use a stable power supply, I recommend at least 12v/2-3A, this mount goes hay wire if under supplyed. Lastly, balancing your counterweight "east heavy" (always make sure the heavier side is to the east of the Ra-axis) will improve the tracking alot.

The mount does not have a meridian flip option. As it passes some 15° past the meridian it will go to a grinding halt (factory set limits). A new go-to command will how ever slew the mount to the correct side of the pier. As will it if the meridian has been passed but the limits not reached.

You should be able to find a manual for the mount with a quick Google search if you don't have a paper version. I do recommend you to read it, mostly to learn how to navigate the menues and options in the hand controller because those can be a maze in the beginning.

I hope this can help, the advanced GT may be old but it's a workhorse :)
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#7 DanMiller

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Posted 03 December 2022 - 03:52 PM

I've had an advanced GT that I started doing astrophotography with. The mount works but can give you some troubles compared to more modern mounts.

First of, the mount should start tracking right after you finished the initial set up, location/time/etc. If not there's an option for this in the hand controller (under "scope set up" if I remember correctly).
Before that you should have roughly pointed it correctly to the north/south.
A common and proved teqnique to get good go-to is to first do a 2+4 star alignment. Then follow up with the ASPA, "all star polar alignment", you can find this option in the hand controller as long as it isn't too old (first edition old I believe).
After the polar alignment you should power the mount off and re-do the same steps as above one more time. This often corrects the most of the pointing error and gives you a better polar alignment.

With the ASPA you don't need any polarscope but use your telescope instead, much like sharpcap/Nina does.

A few other things to remember. Always finish your corrections with the up and right arrow key, this meshes the gears the right way. Always use a stable power supply, I recommend at least 12v/2-3A, this mount goes hay wire if under supplyed. Lastly, balancing your counterweight "east heavy" (always make sure the heavier side is to the east of the Ra-axis) will improve the tracking alot.

The mount does not have a meridian flip option. As it passes some 15° past the meridian it will go to a grinding halt (factory set limits). A new go-to command will how ever slew the mount to the correct side of the pier. As will it if the meridian has been passed but the limits not reached.

You should be able to find a manual for the mount with a quick Google search if you don't have a paper version. I do recommend you to read it, mostly to learn how to navigate the menues and options in the hand controller because those can be a maze in the beginning.

I hope this can help, the advanced GT may be old but it's a workhorse smile.gif

This was a huge help.  Thank you.




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