Celestron NexStar Evolution 8 - alignment query

[laf87]

Hi

I have just started using the Celestron NexStar Evolution 8 and for using the wifi link to Connect and Align via SkyAlign, the handbook says that to align it just move the scope to the first star using the controls on the screen, click align, then the second star, etc. I had wondered reading this in advance how it knew where the scope was pointing to start with, to know where it was going. And when I came to align it the first time, I used the keys on the screen to move it to Capella (nice and bright) but when it was pointing at Capella on screen, the scope itself was about 15 degrees too low. So it seems the scope doesn't know where it is pointing to start with!

I checked my latitude, longitude and elevation and these all seemed right. Eventually I seemed to fudge it by balancing my iPad on the scope, using the compass to say where I was pointing, centring it (I think), clicking on the star, etc - I don't quite remember everything I pushed to make it work and recognise where it was and what it was pointing at. Once it knew where it was the rest of the align went fine and the GoTo feature was great, as is the viewing through the scope.

So the query is, how does the scope know where it is pointing at when it starts the alignment process? Or should I go to a star manually and then go into the SkyAlign process? 

Thanks very much

Lori-Ann

[laf87]

Sorry, I realised the short version of the query above is: when one is going to start aligning using an ipad and SkyAlign, should the scope be pointing at the horizon and also pointing due north in order for its position to match that of the cross-hairs on the screen? The instructions don't say to do this but otherwise how do the crosshairs know where the actual scope itself is pointing?

Thanks

Lori-Ann

[BeanerSA]

When you plonk it on the ground, it has no idea which way it is facing. Alignment involves you moving the alignment stars into the centre of the eyepiece yourself. This is why it's important to correctly align the finderscope during the day, and then you need to be able to identify the alignment stars yourself. This is why we say that these scopes aren't as easy to use as they initially appear.

EDIT: I might be mistaken on a couple of points so I'm just reading the manual now.

[BeanerSA]

So there is no starting position for the scope, which is good. 

The alignment procedure is on page 10 of the manual, and I was incorrect about needing to know the name of the stars. It just wants you to centre 3 bright stars. Can you see 3 bright stars, preferable some distance away from each other?

[BeanerSA]

I've gone back and re read your first post. I think the issue is just that you need to ignore the stars indicated on the screen until after you've done your alignment. You just use the arrow keys to centre 3 stars, pushing align each time.

Here are the relevant steps.

3. Use the arrows on your screen to move the telescope to any bright star in the sky.

4. Center the object in your StarPointer and tap Enter. Now that the object is centered in the finder, the motor speed will slow down so that you may make gradual adjustments to center it in the eyepiece.

5. Center the star in your eyepiece and tap Align. This aligns your first star.

6. Choose another bright star, in a different part of the sky. Move the telescope to the second star and repeat steps 3-5.

7. Repeat this process for a third star in another part of the sky. Upon completing the third alignment star, your telescope will be aligned. You are now ready to observe!

[ejp1684]

Lori-Ann, forget about looking at where the cross hairs on the screen are while you do the align. The scope doesn't need to know where it's looking initially. It works out its position from its database once you've given it three stars. Here's how I do it.

1. Make sure the tripod is firm and level. I thought the little spirit level on the tripod top wasn't good enough, but actually it is. Just get the bubble in the centre and it will be find.

2. When the scope is switched on and the app connected, I manually get a bright star in the finder and then tighten up the clutches, but you can do this with the buttons on the app if you prefer. (Make sure the finder is already aligned with the scope.)

3. Tap Enter, then use the buttons to centre the star. Tap Align.

4. Repeat for the next two stars. It helps to select three stars which are well separated and not lower than 30 degrees or higher than 70 degrees (read this in another post).

Hope this helps.

Eric.

[ejp1684]

Sorry BeanerSA, you got there before me!

[laf87]

Hi all

Thanks for that - it is good to know I am on the right course for the alignment procedure, which seems easy enough. But when I click on Connect and Align, the crosshairs are pointing to a different place than the scope. So when I move the scope to, say, Capela for the first alignment, the scope is pointing there but the crosshairs are 15 degrees off. So when I click Enter and then Align, has the software aligned with the point 15 degrees off? And then so on for the other three stars? Or does the system self-correct once the three points are aligned?

It just appears that because the cross-hairs and scope are pointing at different places to the scope, that the end alignment will also be 15 degrees out too? But I will try it again tonight (hopefully) and see if it does self-correct.

Thanks very much

Lori-Ann

[BeanerSA]

Or does the system self-correct once the three points are aligned?

I would say that is the case.

[ejp1684]

So when I move the scope to, say, Capela for the first alignment, the scope is pointing there but the crosshairs are 15 degrees off. So when I click Enter and then Align, has the software aligned with the point 15 degrees off?

Not yet. It does all the alignment once all three stars have been set. After you've set the third star and it tells you the alignment was successful, then it will tell you the last star you selected and the cross hairs will be correctly aligned to that star.

Eric.

[laf87]

Thanks very much, guys. That's all really helpful. I hope the high haze will hold off so I can do an alignment test this evening, even if it isn't great for viewing.

[laf87]

Done and test and it, indeed, all seems fine. I should learn to trust technology more! Thanks for all your advice; much appreciated.

[JG777]

Or you can manually align. Point the scope at your chosen star, say for instance Polaris and get it dead centre. Then on the app set the cross hairs onto Polaris press align and the app will ask you if you want to align the scope with Polaris. Hit yes and your done.

(Forgot to add, the above after you have connected the app to the scope)

[ejp1684]

Or you can manually align. Point the scope at your chosen star, say for instance Polaris and get it dead centre. Then on the app set the cross hairs onto Polaris press align and the app will ask you if you want to align the scope with Polaris. Hit yes and your done.

Thanks for posting. Haven't tried that, will give it a go next time.

Eric.

[NosyTrader]

Lori-Ann, forget about looking at where the cross hairs on the screen are while you do the align. The scope doesn't need to know where it's looking initially. It works out its position from its database once you've given it three stars. Here's how I do it.

1. Make sure the tripod is firm and level. I thought the little spirit level on the tripod top wasn't good enough, but actually it is. Just get the bubble in the centre and it will be find.

2. When the scope is switched on and the app connected, I manually get a bright star in the finder and then tighten up the clutches, but you can do this with the buttons on the app if you prefer. (Make sure the finder is already aligned with the scope.)

3. Tap Enter, then use the buttons to centre the star. Tap Align.

4. Repeat for the next two stars. It helps to select three stars which are well separated and not lower than 30 degrees or higher than 70 degrees (read this in another post).

Hope this helps.

Eric.

Point 4 on here I really useful. I wasn't actually aware of this. My alignment is at times off by a few degrees which is pretty annoying, I'm thinking now that I've not been observing the 30/70 rule, which may help me - thanks for posting!