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Caveman

Nexstar 8 SE help needed please.... AGAIN!!

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Hi, I said I might be back on here asking for some help again... WELL here I am, HELP ME PLEASE SOMEONE!!!! Have just been out for an hour or so trying to test my new 3 week old telescope (boy it was cold!) before the clouds started to roll in again here in Lowestoft.

This time I tried a 2 star align, first I aligned on Alpheratz in the Square of Pegusus (top left of the square) then on Polaris, the scope told me SUCCESS but when I tried a tour, every object the scope went to was not in the 25mm eyepiece, when I asked it to goto Jupiter it was about 2 degrees out.

Cant think what I am doing wrong, put the date and time in correctly.

This is my second night out with the new scope since buying it 3 weeks ago from FLO, I accept that the problem is very likely my fault.

And it's a very cool scope but if it cant point with any accuracy what's the point?

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I don't know if you did this:

When doing the star alignment use the highest power EP you got and center the star as well as you can. This will make it more accurate.

If you did I'm out of ideas.

ps-> Test the goto on an object you know on the same area of the sky as the stars you used to aligned. I only used my goto a couple of times but it was far more accurate when I asked for objects in the same region as the used stars.

After aligning my control displays "Success!" with an error margin in degrees. According to the manual this value should be under 0.5 for ideal results but I found it hard to get even near that error margin without using a high mag, 240x EP for the job. The instructions in the manual are to repeat the alignment if I get error margin over 0.5, despite the success message.

Edited by pvaz

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Don't have a Celestron but:

Daylight savings: is it off? (would give a nice 15 degree shift)

Lat, Long being the next.

No idea about the Celestron but I think that the Meades can be set for the correct time, given the Lat/Long and still somewhere have the time zone defined as PCT (Pacific Central Time).

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have you put in the correct longtitude and latitude for you location ?

when i star align i center the star in a small mm eyepiece, i find it helps alittle doing this, hope it helps

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I'm not sure if this applies to celestron

but I would not use Polaris as an alignment star unless you have to

Edited by Ibbo !

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Just thinking about this. My Meades need to be pointed North then aligned. Assuming similar for the Celestron's I would have thought that using Polaris as an alignment star was a poor choice.

Also, if similar, the alignment stars for the Meades are usually East and West of a North-South line. Would make sense to get better determination of errors that the scope has to compensate for. You appear to have chosen 2 stars that would be on the North-South line. This would give the scope little chance to determine any slope on the scope in either East or West directions. Would have thought that Capella and Vega would have been a better choice assuming that the start position was North.

All this depends on the two makes using a similar alignment method.

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Hope to get another try later tonight (not holding my breath as it's started to snow):D but thanks to everyone who has responded.

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I have found that apart from on one night my Nexstar runs very relaibly.

I would suggest the following. Blow the hand controller back to 'Factory Settings' - its in one of the menu options.

Now take the scope out and align using SkyAlign - the auto method

Pick three bright stars - make sure they ARE stars and not planets or even passing aircraft.

Make sure the stars are well seperated in a loose triangle - ie one to the east and lowish , one to the west at medium height , one to the south and high up.

Make sure your date and time is set correctly DST at this time of year should be set to ON.

Make sure you lat and lon are correctly set.

Line up the Nexstar using its red dot finder for on one of thge bright stars you picked. When centred in the red dot DONT press ENTER as the manual tells you...... Look in the scopes EP and centre it while in rough alignment NOW press ENTER. The scope will ask for fine alignment. Carry out any fine tuning and press ALIGN.

Basically what your doing is getting the alignment as perfect as possible before doing the fine tune alignment - ideall you dont use the fine tune at all.

Why Not ? Well the Nexstar is my experience can get [removed word] about things thanks to its gears and their backlash. If you can zero in as close as possible at the off rather then getting into the up-a-bit-down-a-bit-left-a-bit etc it seems to help.

Another Tip - always try and approach the target in the same way - ie decide to use UP and LEFT. Then use that for EVERY star alignment.

Using this process may help you. If you still stuck let us know.

I seriously recommend blowing the handsets settings back to Factory though. I am convinced that was the cause of my woes at the SSP where my Nexstar refused to align.

While I was at it this week I also did the software updates for the scope. Might be worth it in case there are any gremlins in the version you may have.

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ps - I know its frutsrating but dont give up - most scopes have their foibles and very little in the world of astro is plug and play. Be patient - work the problems and I am sure you will be rewarded.

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Mine works fine with DST set to on - did it last night and it was fine. perfect alignment. Shrugs - explain that and stay fashionable.

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If the is polar aligned it does not need to know the time only where it is pointing (good alignment stars)

the separation between the stars remains(well from our aspect) remains the same

ie if say you tell it its pointing at Rigel it will know it has to move up in dec about 15deg north and 40mins(about 10 deg) in RA to Betelguese

this remains the same no matter what time it is

hope this is clearer than mud

Steve

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In theory if you get the time wrong it should screw up the first alignment star, i.e. be way off but otherwise it makes little difference after you've aligned it.

I never was fashionable Mel, and I'm not going to start now :D

James

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Just a thought, when using 2-star alignment, are you choosing the stars or letting the system do so? I tend to select my first star from the list, align it, and then let the GOTO select the second one - it's always within fov of my 32mm eyepiece, then go back to higher power to centre it. Mine has never selected Polaris, and I would echo the previous comments of going to the next star offered if it does so.

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I usually align, using the manual 2 star align on Polaris and Vega, never had a problem finding anything else. I usually have to reset the date/time but then align on the two stars above, no probs.:D

si

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I'm new to the Nexstar 8 and GOTO foibles so am learning a lot from others posts. The Nexstar Users Handbook recommends Polaris as a first alignment star. Is there a difference between setting the GOTO if the scope is alt-az or on an equatorial wedge in this respect.

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Yes there is Peter..if using your telescope on an alt/az mount that is what the goto should be set to,,if using an equatorial mount or wedge then set it to equatorial.

When using an alt/az mount the goto has to track the sky in RA and Dec,,If using the equatorial mount or a wedge the goto only needs to track in RA so less room for error..

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You can use polaris if you are setting up in Alt Az mode, but not in equatorial mode.

Helen

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Thanks Dark Knight, I'm familiar with alt-az and equatorial mount differences, it's just that there seems to be variable advice as to the star alignment for GOTO performance. For instance, there seems to be a different requirement for Meade versus Celestron procedures. Helen, in her post, confirms one of the differences.I have a Nextsar 8 SE in Tenerife which doesn't drive until the GOTO preamble is initiated although a one star alignment on Polaris gives a good enough drive for visual use. My 16" LX200 in the UK, when it was mounted alt-az just needed to be reasonably levelled and orietated roughly N-S to acheive the same result.

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The weather looks ok for another try tonight! i'm not giving up and will let you know later how I got on... :D

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If you are using a power pack try to find some way of keeping it insulated and above 0 degrees. They don't like the cold - used to play havoc when trying to align my NS8

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If you are using a power pack try to find some way of keeping it insulated and above 0 degrees. They don't like the cold - used to play havoc when trying to align my NS8

I used my Celestron powertank at -12 C for a 90-minute session without problems.

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