silly question about goto

[burningbarricade]

Hi there,

I have a http://www.firstlightoptics.com/proddetail.php?prod=skywatcher_skymax_102_az_goto

and the other night had it set up in the garden and tried to align the goto for the very first time.

I understand what I'm meant to be doing but I keep loosing stars in the eyepiece before I can get it set up. Basically I get the star in the finderscope and then center it in the 25mm eyepiece (isn't that the least magnification one?) then switch to the more powerful eyepiece and try and center it in that. Then if I managed to get it in that I'd try the barlow lens but i've not gotten that far as yet.

Things seem to drift out of the eyepiece so quickly at higher mags that I'm not getting a precise alignment. After my best attempt to align it I instructed the scope to look at the moon. It went in the general direction of the moon but hardly what you'd call even close.

Is there something I'm missing or is it a case of practice makes perfect?

thanks

[blinky]

Have you done a basic polar alignment? ALso you dont need to use a high powe eyepiece. I use arund a 10-15mm and try and get it in the center. I would say though that if stars are drifting that quickly then you may need to revisit your polar aligment.

[burningbarricade]

I wasn't aware that I had to have it polar aligned, I thought I just had to punch in my location co-ordinates, the time, date etc then align it to 2 stars.

Off I go to find out what polar alignment is (well that sounds obvious actually) and how it's done Obviously I've skipped over that part in the manual somehow. D'oh!

[blinky]

No no, sorry looks like you dont need to polar align that scope/mount. Not sure whats wrong, I am sure others will be along soon with the answer.

[Texy]

Perhaps as this scope has a alt-az mount rather than equitorial mount, it does not require polar alignment?

Texy

(taking a small step into returning to the hobby!)

[James]

Using the 25mm eyepiece will be more or less sufficient if you are careful to centre it properly. Defocus the star until it fills lots of the field of view and the resultant blob will be easier to centre.

Ideally though you should use the 10mm. I wouldn't worry about the barlow as well as that. If you can centre a star using the 10mm that will be more than enough.

James

[daz]

I would've thought at the very least it needs to point North and level at first set up?

In fact, looking at the handset and mount, I'm sure this should be the case.

[jgs001]

On the Celestron NexStar, which looks to be identical, there is no requirement to get it pointing north in any way. Make sure it's as level as you can get it though, I use a proper spirit level to do this, also what are you using to power it ? I don't know if that'll take AA batteries like the NexStar, but they can't deliver the necessary grunt. The tracking motors don't kick in until the mount is aligned, therefore I suspect that the long focal length of the scope is causing the effect that the rotation of the sky is fast enough to drift the star out of the FOV before you've got the alignment sorted. I've seen this effect on my C80ED on the NexStar, and that's less than half the focal length, if I wasn't fast enough with a 5mm Ortho.

[daz]

So, how does the computer know where it is if it is not set at North John?

My son has an older model, and my memory is shot!!!

[Helen]

Do I remember reading somewhere that this scope doesn't start tracking until the alignment is complete? That could explain why stars move quickly in high mag 5mm = 260x). I'd just use the 25mm to start with, but centre carefully, and then see how accurate the goto is. You might also want to check that you input the date in the right format...we've all done it wrong at some point

http://stargazerslounge.com/index.php/topic,35242.0.html might help

Helen

[daz]

Ah OK.

Understand now. The alignment routine tells the computer where it is.

OK, I'll shut and go back to sleep

[jgs001]

So, how does the computer know where it is if it is not set at North John?

My son has an older model, and my memory is shot!!!

Daz, on my NexStar, you provide, it the Date, Time, Long and Lat, and at least one reference star, from that it works it all out. My normal process, once levelled as carefully as possible, as the Long and Lat are already set, is to set the current date and time, pick one star I know (Betelguese for instance), align that with the 5mm Ortho defocused. The computer does the rest. Goto it pretty accurate to the point, that in most cases, the target is in the FOV using my 17mm Hyperion, and normally towards the middle.

[jgs001]

Sorry Daz, you beat me to it .

[SilverFox]

Hi all. I just managed to gt enough sky to get my nextar 6se out and aligned. Managed to get there in the end, but just wanted to say thanks for the tip about defocussing the star to aid centering, well worthwhile reading this thread! Will try it next time...

[scotastro]

Been away a couple of days so first oppotunity to read the post.

I have the 130mm reflector version which uses the same mount. There is no need to point the scope north, but it is important that the scope is level, use the spirit level built into the tripod and adjust the leg height if needed.

Make sure you have the day input into the handset in USA format ie mm/dd/yy and put in the time GMT.

As James said the 25mm eyepiece is good enough for doing a star alignment. The motor drive is only activated once you have aligned the scope so push the enter button as soon as you have the star centred.

You can realign the scope at anytime when observing if the scope seems to be inaccurate, but I found it was pretty good right across the sky.

Mike