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Hi guys! id really appreciate some help on a problem i've been having, i've got a little celestron nexstar 114slt and i can't seem to get the goto working for love or money!

I've been intrested in astronomy for about two years and have a basic understanding, can find bout 20 m objects and the easy planets with a dob but when i try to set the goto up it doesent play ball.

my normal routine is:

Get the scope level,

Pick two star align

enter in the time, date, longitude and lattitude, daylight savings etc(i'm 99% sure these are all right)

and align to two stars (i normaly pick deneb first and vega second) and get them in the center of the eye peice.

the handset says alignment sucsess,

however if i tell the goto to point at vega(which iv'e used as my second star) when i already have it in the eye piece, after having set up the goto it slews up and to the left, then slews straight back to vega, bang on in the center of the eyepeice,

Fantastic!, i think.

however, when i then tell it to point back at deneb (the first star i 've aligned to) it slews about an inch to below where deneb is!!

had a friend who is really in to imaging and knows quite alot try to set it up and exactly the same thing happens to him!!

He said about updating the software on the goto ( it must be 2 -3 yrs old at least, second hand scope)

any ideas or help would be fantastic, at the moment i dont bother using the goto ,and just use maps from cartes du ceil to try to find objects myself, but i'd really like to get it working properly!!!

other than this it's a nice little scope!!!

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I've just got the Nexstar 127 SLT and I don't have to enter the location each time as it's already saved for the last setup.

I also have an option to choose three stars, which is the default setup and (I would assume) more accurate.

Do you have this on yours or just the two star setup option?

I've only had it a week or so and only had one clear night to play with it but it aligned first time using the three star option. I did notice that, using the 25mm eyepiece, some of the objects were right on the left hand edge of the viewable area.

I need more clear skys to practice as it may well be me. :rolleyes:

Edited by Budgie

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I dont really know as i dont have a goto,but from what i understand maybe your alignment stars are a little to close to-gether,maybe one in the East and another in the West.As i say this is just an observation,and maybe someone can really help.

regards.

Mick.

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It could be, Mick, the instructions say to use stars that are as far apart as possible.

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I can't say I've ever had that problem with my NexStar SLT. It's at least 18 months old. Do you have the SkyAlign option on the handset ? You pick three bright objects, anyones you like including planets, and the mount works it out from there. Try that if you have it. When you centre in the ep, what ep are you using ? I also found it easier to align with the scope a little out of focus, so you get a fuzzy ball instead of a pinpoint star

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I found (the Synscan) GoTo to be a total frustration - in much the same way? For me anyway, problems similar to the above, were solved by improving the rigidity (reducing the extension) of the tripod, setting up on an area of hard standing etc. That way the scope doesn't wobble or "dig into" soft ground - Even in the "sun-baked" UK. Maybe not the answer, but worth eliminating as one possible source of error though... :rolleyes:

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I've always had problems going to deneb with my 114slt, I've tried to use it like you to measure the success of the alignment, but the scope it seems to want to point below the horizon - I suspect there may be another star called deneb that it's aiming for.

It works fine for me for all other objects that I've chosen - it's just deneb that doesnt work.

Does it work if you choose other objects to goto?

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What eyepiece are you using? You need a high power to align (a crosshair helps as well), but don't expect the goto to then work at that high power (on a Nexstar SLT mount). I can usually get objects within the 25mm supplied eyepiece on my 102SLT (660mm FL) using a crosshair 20mm eyepiece barlowed to 10mm.

NigelM

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Thanks for the ideas, i've used the three bright object alignment before and still no luck, when i'm aligning i use a 25mm eyepeice, i'll have a crack at putting the scope on my patio (normaly take it in to a feild behind my house because i can see 360 degrees there!) so it has a solid surface, and have another go at using some of the other alignment options again.

the odd thing was, my friend has an eq6 for imaging, we set them up side by side (in the feild) and used the exact same data, time and stars etc, his was absolutly fine!

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I would suggest, in case you are not doing it, to set the mount/tripod up so that the base plate of the goto is level, then point the scope due north, and level the scope tube. Then do the alignment.

The Meades start with this arrangement and I suspect that it helps. It is effectively a virtual star but I would suspect that the biggest advantage is that this is a datum position.

Someone in the Cambridge area had similar problems and found that this helped. Mind you I think they also were so pee'd off that they levelled+North then did a 3 star alignment, but as I recall it rectified the problems.

The SW/Celestrons allow the user to simply place the scope then go finding alignment stars. If the errors that the scope has to allow for are too great it will I guess cause problems and Level+North also appears a decent start point. Good start point if n0n-astro people are around in that you can point out polaris and say that you use this as a basic alignment/setup.

If the SW?Celestrons use their 2 star alignment then what is the first aligned to? As best I can tell nothing so the scope has only the difference between the first and second to get its errors calculated and not sure how feasible this is.

I do wonder if this isn't a bit like the huge magnifications advertised, in that you can do a 2 star alignment (If you are lucky+fortuate).

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I never use two star on my Nexstar I just use SKyalign and go for three bright objects and normally all is well.

Skywatcher eq mounts do have a start point which is the scope in a park position and with the mount polar aligned.

I would suspect either the scope isnt level OR there is some kind of software screw up so a reload may fix it. I had a similar issue with the Nexstar after last years SSP where it got so cold the scope just failed. Afterwards it could never find anything and would miss every target by miles - a software reload cured it. Your problem might also be caused by the alignment stars being too close together OR some other reason - the Celestron manual does say they should be far apart and also some other condition but I cant remember what.

Edited by Astro_Baby

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Deneb and Vega are definitely too close together. I've been using Vega and Arcturus with good results. The results for the EQ mount could have been more accurate as it is implicitly aligned on Polaris too.

Apparently the NexStar never uses more than two stars for alignment. The Third star in SkyAlign is only to help identify the bright objects you selected. After identifying the objects, NexStar then uses the best two objects to establish an alignment. At least, that's what I've read somewhere.

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No one seems to have mentioned it yet so I will, appologies if it has been mentioned ans I have missed it, how are you powering the mount? You NEED a really good powwer supply for use with goto scopes.

Try using a car battery or a mains adaptor, dont use AA's, they seldom are a great success.

HTH,

Gary

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Yep, you can head & see the difference when you plug the mains adaptor in.

Mine was OK at first on fresh AA's but that doesn't last long and it really starts to slow down.

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Using a GoTo mount i found it hard to get aligned at first but agree with comments above. I 2 star align on my scope and use Stars as far apart as possible. It's also possible to Polaris and then any main star as far as it's a far away in either direction. Think the worst i've had mine out was by -0.94 degrees think that was due to me not setting daylight savings though.

Try using a car battery or a mains adaptor, dont use AA's, they seldom are a great success.

Quick note on the Quote above. I use Rechargable AA's for my mount. Tend to work just fine and can still give hours of usage without the extra bulk or weight of a Car Battery especially while out in the middle of a field. :)

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