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Equatorial Mount


GOwenC

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Greetings,

I bought my 15 y/o son the Nat Geo branded NG114mm Newtonian scope with equatorial mount for Christmas. Despite watching some videos and trying to digest some written instructions on how to properly set up the equatorial mounts we just can't seem to get our heads wrapped around it. The instructions all seem to be very obtuse and arcane. As an aging orienteer, I believe I understand the concepts of orientation, azimuth, declination and whatnot clearly enough but somewhere the dynamic nature of the mount in relation to these concepts eludes me. Can anybody here point me to a very clear and concise explanation on how to pull this all together? I'd appreciate it.  Thank you.

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1 hour ago, GOwenC said:

Greetings,

I bought my 15 y/o son the Nat Geo branded NG114mm Newtonian scope with equatorial mount for Christmas. Despite watching some videos and trying to digest some written instructions on how to properly set up the equatorial mounts we just can't seem to get our heads wrapped around it. The instructions all seem to be very obtuse and arcane. As an aging orienteer, I believe I understand the concepts of orientation, azimuth, declination and whatnot clearly enough but somewhere the dynamic nature of the mount in relation to these concepts eludes me. Can anybody here point me to a very clear and concise explanation on how to pull this all together? I'd appreciate it.  Thank you.

Here is a link to a video explaining how to set up your mount correctly, and how to polar align it. There are many such videos on youtube. I hope this helps your son.

 

Brian

 

 

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I feel your pain and can remember struggling to get my head around guiding, fortunately I have two very good friends that helped me patiently and would drop everything to pop round when I was stuck.

 

Had I not had their assistance, then I would have joined an Astronomy club and would/still do read a hell of a hell of magazines/online material.

 

Sadly I skipped the route of visually recognising the locations of areas in the sky, I use platesolving instead, but when time allows, then I will share time with my mates and continue to learn with them.

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Thank you for your replies. 

 

So, I watched the video but my confusion remains the same. I can follow all the instructions with no trouble and end up with a leveled, balanced, polar aligned telescope; and... presumably watch Polaris all the live long night. But as soon as I go to look at something else and I move away from Polaris the polar alignment seemingly has become nothing more than a meaningless exercise. Here is where all of the videos and instructions I've been reading fall short. None of these videos talks about what comes next after polar alignment and how do I actually use the equatorial mount to track objects once I focus in on them. What, for instance, is the necessity of aligning my scope to Polaris if my goal is to view objects in the southern sky? 

Edited by GOwenC
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It sounds to me that you are pointing the telescope at Polaris. You should be pointing the axis of the equatorial mount to Polaris. Not sure what mount yours is but some mounts have a small telescope inside the axis of the mount which look through a hollow tube in the right ascension shaft which the mount pivots about.

 

If you are confused by the terminology have a look at Trevor Jones website article on Polar Alignment here https://astrobackyard.com/polar-alignment/

He makes a good job of it and links to his Youtube video which highlights graphically the RA axis, also known as the polar axis, I mentioned.

 

Edited by TerryMcK
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Can you post a picture of the telescope on its mount and tripod so we can determine whether it is an equatorial mount or alt/az mount?

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7 hours ago, TerryMcK said:

Can you post a picture of the telescope on its mount and tripod so we can determine whether it is an equatorial mount or alt/az mount?

This is the telescope he has. The National Geographic NG114mm Newtonian Telescope w/ Equatorial Mount. I see no polar scope on it, but it does come with a red dot view finder that could be used to lock on to Polaris.

 

Brian

 

 

71tqMlBXzML._SL1148_1800x1800.jpg

Edited by AstronomyUkraine
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Yes no polar scope on that one.

I did find this one as well from a quick scour of the internet hence asking about eq or alt/az

02152015-9C69-4752-8529-35B88B39AFBE.thumb.jpeg.065e0ac1be61f789682f83678fe207ff.jpeg

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Original poster if it is the scope with eq mount that Brian linked to then here is some useful information that may get you on the right track

https://www.skyatnightmagazine.com/advice/equatorial-mounts-an-astronomers-guide/

 

This says “For visual observations, you don’t need to be overly accurate in your polar alignment.

It’s just a case of adjusting the altitude setting so it’s the same as your local latitude and pointing the polar axis north so it’s lined up on Polaris.”

 

So read that as pointing in the direction of Polaris rather than getting it spot on which will be difficult with that mount.

Edited by TerryMcK
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Hi @GOwenC, it took me quite a while to get my head around polar alignment when I started first, with a similar scope & mount (Celestron AM135EQ). It sounds like you have probably successfully set your latitude, levelled your mount and balanced your scope, as they're relatively straightforward operations.

 

Polar alignment is an unusual concept, and what confused me at first is that it is completely different to 'scope alignment' or 'star alignment'. As Terry says above, 

1 minute ago, TerryMcK said:

For visual observations, you don’t need to be overly accurate in your polar alignment.

The benefit of proper PA is that when you're tracking an object for a prolonged period (whether it's in the northern or southern sky) you only have to adjust the Right Ascension axis using the slow-mo controls, and the Dec axis should stay bang on target. Having said that, with the mount that you have, it will be very hard to get good PA so I wouldn't stress about it too much. It just means that you may also have to adjust the Dec axis as you follow an object.

 

Again as Terry says, it may be that you're moving your scope during Polar Alignment. Don't! You move the mount during  polar alignment, not the scope. You could actually in theory do PA with no scope attached. The scope is there only so that you can see if your mount is pointing close to Polaris or not. Set your scope in the home position (on top, pointing north) so that it is as aligned as much you can make it with the Right Ascension axis. You'll need to do this by eye as your mount doesn't have any attachments to help you. Now, looking through the scope, if Polaris isn't centered* properly, move the mount until it is. Again, don't move the scope! You may need to adjust the latitude north or south, or actually pick the mount up and turn it slightly east or west. It's also not a bad idea to check that it's still level when you're done.

 

 *When I say 'centered', it's actually the North Celestial Pole that should be centered, but your mount manual probably has a little diagram that shows where the NCP is in relation to Polaris, and there are phone apps that will help such as PolarFinder. 

 

Once Polaris/NCP are centered in the scope, you can assume that your mount is polar aligned. Now you can leave the mount as it is and start using your telescope.

 

Now that your mount is polar aligned, you can observe any particular target by opening the RA and Dec axis clutches and rotating the scope to point at/close to the target. Tighten the clutches again, and use the slow-mo controls to fine-tune your aim. Now you can observe the target, but you'll notice very shortly that it starts to drift out of view. The smaller the eyepiece you are using, the faster it will drift - for example, with a 5mm eyepiece, you might only get 20 seconds of good viewing before the target is hitting the edge of the field of view and you must adjust your slow-mo controls again. This is where good polar alignment helps - you should only have to adjust the RA axis. I found in practice that I needed to nudge both RA and Dec. It can get a bit stressful, especially if you're trying to locate a target to show to a guest - sometimes by the time they've managed to find the eyepiece and look through it, the target has already drifted out of view!!! 

 

Hope this helps. The video posted above is actually quite good if you take it one step at a time.

 

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Hi guys, thanks so much for the replies. I'll have to take the next few days to absorb it all but I wanted to post my thanks real quick lest I become to delinquent. It is indeed the telescope that Brian posted above that my son and I are trying to figure out. I have some other questions and frustrations based on a quick read through of your responses but I am going to hold off on them because I've no doubt that a more thorough read through, as well as following the links provided, will likely answer some or all of them.

 

Thanks again.

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32 minutes ago, GOwenC said:

Hi guys, thanks so much for the replies. I'll have to take the next few days to absorb it all but I wanted to post my thanks real quick lest I become to delinquent. It is indeed the telescope that Brian posted above that my son and I are trying to figure out. I have some other questions and frustrations based on a quick read through of your responses but I am going to hold off on them because I've no doubt that a more thorough read through, as well as following the links provided, will likely answer some or all of them.

 

Thanks again.

The main thing is to find your right latitude. If you are in the UK it will be around 50° or so. Set that on the mount. Take the mount outside, and point it North, use a compass or an app to find North. Once the mount is set up, you can attach the scope. Make a mark on the ground when you find North, then you can place the mount in the same place everytime. That is your basic starting point.

 

Brian

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