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Nextar 8, lat / long question, auto align question

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#1 thyslip

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Posted 29 December 2012 - 09:49 PM

Just upgraded to a "used" Nexstar 8 from a friend. I have a couple questions about auto align.

1. When I enter the lat / long (I'm at 35N, 78W) do I enter the (-) for the long 78W? Or since I have enter W or E, do I leave it positive?

2. The manual says to point scope north horizon to start auto align, does the angle matter very much?

3. I'm not very good with the star pointer, any advice?

thanks for the help, can't wait to try this out, been using a Celestron Astromaster 114 EQ for a couple years and have enjoyed it. This was a steal at $350 with tripod, so decided to upgrade.

Happy New Year,
Tom

#2 Dave Ponder

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Posted 29 December 2012 - 11:08 PM

Tom, let me ask you about question 3 first...what are you having trouble with specifically?

#3 Tel

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Posted 30 December 2012 - 05:13 AM

Hi Tom,

A very warm welcome to CN and to this forum ! :bow::bow:

As Dave says, we need to know what specific issue(s) you have with the star finder, (red dot finder), before definitive advice can be given, but as far as your other two questions are concerned I'll attempt to answer them.

Before starting though, I would recommend that you acquire a copy, (if it's still in print) of Michael W Swanson's 2004/2005 book, entitled "The Nexstar User's Guide" published by Springer Verlag London Ltd. and that you also visit Mike's excellently informative Nexstar website if you haven't already done so.

www.nexstarsite.com/

Also, you may have already come across this CN review of the Nexstar 8 but which if not, might be of some interest to you.

http://www.cloudynig...hp?item_id=1527

But to your questions:

1) What better than if I quote from Mike's book on entering Latitude and Longitude co-ordinates for the Nexstar 8.

Quote:

"If your version of Nexstar asks for + or -for latitude, + is north latitude. It is not generally worth the trouble to enter accuracy beyond minutes of longitude and latitude so if your 'scope prompts for seconds,( a third pair of numbers for longitude/latitude), round to the nearest minute and enter 00 for seconds.

Note that on the original Nexstar 5 and 8, storing your longitude and latitude in adjacent "stored locations" will corrupt the entries. This results in the Auto Alignment procedure missing the two alignment stars. To prevent this problem, only store longitude amd latitude in locations, 0,4,8 or 1,5,9."

Unquote.

I note from the above that he doesn't mention the use of + or - for longitude entries. Puzzling: but if this IS required, (and I'm not that familiar with the Nexstar 8 hand controller version having myself the later Nexstar 8i), then I believe negative (i.e. -) is used for western longitude entries.

2) Tube alignment with north prior to using the Auto Alignment.

(I make the assumption that you set up your 'scope by first levellling it and pointing it due North having established this by viewing Polaris in your eyepiece).(?)

With this in mind, again, I paraphrase Mike's comments:

Quote:

"The older Nexstar models are sensitive to very small differences in the position of the optical tube when the alignment procedure starts. For the Nexstar 8, it is critical to start the alignment with the optical axis and the azimuth axis perpendicular.

The optical axis is basically the centreline of the optical tube. The azimuth axis comes straight up from the centre of the mount.

Auto Alignment, Two Star Alignment and Quick Alignment all require that you point the telescope north and "level" but actually what is needed is to set the optical and azimuth axes perpendicular.

There are two ways to insure you start perpendicular. The first is to set up the tripod, without the mount and 'scope, and accurately level the top of the tripod. Then mount the 'scope and accurately level that. The more accurate you are at this two step levelling, the better the "GoTo" performance you will receive.

However, a simpler and faster method also proves to be more accurate.

Set up the tripod and level it precisely, rotating the bubble level around the head of the tripod to insure accuracy. Then mount the 'scope on the tripod and carefully level it, using the "Up" and "Down" buttons on the hand controller to make adjustments. Use a rate or 4 or lower to make small movements.

When level, place a piece of tape, (masking tape is recommended), on both sides of the joint where the fork arm meets the optical tube holder. Then use a short ruler and mark a straight line across both pieces of tape.

From this point on, you will not even need to remove the 'scope from the tripod, just roughly level the tripod. Note that the more accurately you level the tripod, the closer the 'scope will be when initially pointing at the two alignment stars. When therefore the hand controller prompts for "north and level", aim the 'scope towards the north and line up the index marks on the tube and fork arm".

Unquote.

Hoping this helps,

Best regards,
Tel

#4 thyslip

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Posted 30 December 2012 - 08:16 AM

Tel and Dave thanks so much for the responses. I'm so glad I found CN, great site with tons of great info. I will check out sites you recommend and also pick up a copy of the book.

I will try what you recommend for auto align, maybe the +/- is for the latitude, it asks for it after entering the lat and right before you enter the long, so I assumed it was long from my work with old GPS units. IT was confussing however because you have to enter N and W, so I thought the +/- was answering the question twice, like a double negative. :)

As far as the pointer, I've never really used one, the pointer on the 114 was terrible, so I just winged it and started with low mag, found the object and worked in. So, I'm really not sure how to use it properly? I've read, keep both eyes open and I 'm not sure if it is better to look through the pointer from a little behind it, or up close,etc.

My friend did give me a Telrad reflect sight in the box, so was considering mounting that, but thought I would start with the pointer and worring about installing the Telrad in the future, since I don't know how to use one. LOL.

Thanks again,
Tom

#5 jturie

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Posted 30 December 2012 - 09:53 AM

It's possible that your finder is not aligned with the main scope. Easiest to do that during the day. Center a far-off object (telephone pole, chimney a few doors down) in the eyepiece. Now look thru the finder. If it's not pointing at the same place, use the two adjustment wheels on the finder to nudge the dot until it's pointing at the same spot. In my new 6SE, it was so out of whack that I could not adjust enough to get the finder in alignment. Believe me, that is a headache when you are trying to set up the goto.

If you end up having the same problem, other folks here on CN told me to loosen the mounting screws and try to jiggle the finder or to shim the finder with something like small pieces of playing cards. Haven't tried it yet, but I will.

You must have an older firmware version--I have the new handset, and I just enter in Lat/Lon and toggle between N/S and E/W on the subsequent screens. My firmware was already defaulted to US, so it was smart enough to display N lat and W lon. You should be able to update your firmware.

#6 Tel

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Posted 30 December 2012 - 10:54 AM

Hi Jack, (Hi Tom),

I'm afraid you'll find that neither the Celestron 8 nor Nexstar 8i original hand controller firmware is upgradable.

The Nexstar 8i, however, will support the most recent of hand controller firmware so long as the hand controller itself has been replaced for a modern, 8SE version 4+ type, but unfortunately, this does not apply to the original N8's hand controller.

Best regards,
Tel

#7 Bob Griffiths

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Posted 30 December 2012 - 12:21 PM

Are "we" all on the same page as to what scope the Original poster actually has...

Is it a NS8 with version 1.xx an done port in the base or it is an n NS8i running version 2.xx and with 2 ports in the base of the scope...

Which one are "we" really talking about...

Its windy and cold, snow is on the ground,and I'm Grouchy this morning..

Bob G

#8 Tel

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Posted 30 December 2012 - 01:11 PM

Could be either Bob. (?) For certain it ain't an 8SE and therefore, with it being either of the other two, the HCs, whether version 1 or 2, are not upgradable.

It sounds though, as if Tom is correct in his description in that he's got a Nexstar 8 rather than a Nexstar 8i; there being no mention of any index marks which we have on our NS8is but which never appeared on the NS8.

Anyway: cheer up my dear friend: you might have the cold and snow but that's fleeting: Spring is on the way ! :waytogo:

We, on the other hand, have been paddling around here in so much water since about June with still no end in sight !

(Even my depression is submerged in the stuff nowadays) ! :4

Happy New Year to you and Mary and may the cold and snow soon pass !

From one :4 :gramps: to another :4 :gramps:

Best regards,
Tel

#9 thyslip

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Posted 30 December 2012 - 01:25 PM

Hi all. I believe it is an original 8.

I have the original box and it says Nexstar 8, # 11011.

There is also a sticker that says, Celestron Nexstar 8, product # 2171, and item no: *428605. Not sure if this means anything, but thought it might help identify which version it actually is.

Also, the HC does have the comm port on the bottom, if that means anything.

Tel is correct, there are no index marks and the tube is bolted to the arm.

BTW, took your advice and aligned the star pointer with the scope on a pole, worked well. Also, I mounted the Telrad while I was at it, I figured 2 is better than 1.

Thanks again
Tom

#10 Tel

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Posted 30 December 2012 - 01:37 PM

Hi Tom,

One other confirming feature, as Bob points out, is that with the Nexstar 8 there are no "Aux" or "Auto Guide" ports on top of the mount's battery container which ARE present on all later models.

Best regards,
Tel

#11 thyslip

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Posted 30 December 2012 - 02:11 PM

Thanks Tel, that is correct, there are no ports on top of the battery container. Pretty confident it is an "8"

#12 Tel

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Posted 30 December 2012 - 03:07 PM

Hi Tom,

Yes, that's an "8" !

Good luck with your alignments etc. but if you do happen to have any other problems, there are plenty of folks here to lend a helping hand ! :waytogo:

Best regards,
Tel

#13 thyslip

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Posted 30 December 2012 - 04:05 PM

Thanks again, looks clear tonight, so I will be out in the cold!

#14 Tel

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Posted 30 December 2012 - 06:50 PM

Hi Tom,

Good luck and don't forget to keep us posted as to the outcome tonight. :waytogo:

Best regards,
Tel

#15 thyslip

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Posted 30 December 2012 - 10:50 PM

still a little frozen, but had a good session. I still didn't get the auto align to work correct, it slews to a star, but I don't see a star, or there are numerous stars in the view. So I'm not sure which is the correct star to align on. Any way, will get it at some point.

Viewed the moon, tried some filters, it was so much brighter than the 114. So clear, amazing.

picked a couple bright stars, and viewed those. The Telrad worked great for a pointer, star was center view each time.

By then, I was frozen and packed up.

#16 Tel

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Posted 31 December 2012 - 05:02 AM

Hi Tom,

Well, it does seem as if the optics are fulfilling their promise ! They always were first class !

But as to Auto Alignment: assuming that you have your long./lat. now entered correctly plus your time zone followed by the appropriate entries of time and date, there should be no reason why the slewing accuracy should be impaired.

If it is possible, make Polaris you first alignment star.

I have not carried out an Auto Alignment on my Nexstar 8i for years, (having placed the tube permanently on a German equatorial mount in my observatory), but if I recall I used to assure an initial North /South alignment by firstly roughly aligning my 'scope assembly with Polaris. Then, after a quick search using the finder, (Telrad in your case), placing Polaris in the 'scope's eyepiece merely by manovering the tube with the direction buttons of the hand controller.

Once in the eyepiece, I would then drop the tube to the horizontal and, in my case, line up the index marks between mount and tube. (As we discussed previously though, your tube does not possess these so you will have to either use a level or construct marks from a piece of tape). This done, you are ready to make your Auto Alignment.

Remember that if the first Alignment star the hand controller selects for you is not Polaris, you can always change this by pressing the 6 or 9 buttons on your hand controller until Polaris is displayed. By similar token, you may also select an appropriate second star by this means, (after all, what the hand controller might offer you initially, may well be obscured by a tree, building, etc).

When choosing the second star however, try to choose one somewhere between 90 and 120 degrees in either direction from Polaris and at an altitude not exceeding ca.70 degrees nor lower than ca. 30 degrees. (For example, Procyon might be used at this time of year).

Hoping this may help you further but if you ARE aware of all this, then please disregard !

Best wishes for a Happy, (viewing) New Year, :waytogo:
Tel

#17 Tel

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Posted 31 December 2012 - 06:03 AM

By the way Tom, if, for example you use Procyon or any other second alignment star for that matter, don't expect it always to be within the field of view of your eyepiece; particularly if you, (by choice), are using a short focal length/high magnification one. (I personally use a wide field 25mm).

Thus if it's not in the eyepiece, just centre it in your Telrad to put it into the field of view and then work from thereon in.

You won't be able not to recognise the second alignment star: it should be the brightest in whatever region of the sky it sits !

Hoping this helps a little further.

Best regards,
Tel

#18 Midnight Dan

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Posted 31 December 2012 - 09:32 AM

... I was frozen and packed up.


:lol: The best accessory you can get int the winter is warm clothes! Since astronomy is not exactly an athletic pursuit ;), you should dress as if it is 20 degrees colder than it really is. And any breeze is a killer, making it feel MUCH colder.

But if you get the right outfit, winter can be a great time to observe!

-Dan

#19 thyslip

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Posted 31 December 2012 - 09:37 AM

All great advice Tel, thanks again. Happy New Year!

Dan, I might have to dig out my old Army winter gear.

#20 thyslip

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Posted 04 January 2013 - 04:17 PM

Received the Nexstar user guide book and have been reading the nexstarsite.com. One question, is the original HC replaceable? Can I purchase upgraded HC? I read that the newest version 4 HC is not compatible with the original 5/8, but what about the 8i or GPS HC? If I can find one, would it work?

Thanks

#21 cn register 5

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Posted 04 January 2013 - 05:37 PM

Yes, the Version 4 HC is compatible with the 8i and GPC scopes, so is the Nexstar+ HC. You may need to update the motor controller firmware.

Chris

#22 Tel

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Posted 04 January 2013 - 05:57 PM

Hi Chris,

This is indeed true but to my knowledge these versions are incompatible with the Nexstar 8. In similar vein, the Nexstar 8i's HC is also incompatible with this earliest of models. The Nexstar 8's HC is not upgradeable or replaceable with any later version.

Best regards,
Tel

#23 thyslip

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Posted 04 January 2013 - 06:12 PM

unfortunately, that is what I thought. Oh well, I will use this and make the best of it. Then maybe down the road, get a new mount/tripod and keep the scope.

Clouds moved in right at dusk tonight, darn it!

#24 SkipW

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Posted 07 January 2013 - 07:56 PM

Just to go back to the original post, I don't think your questions were answered as clearly as they might (but maybe I missed an obvious answer reading all the posts quickly).

If it wants you to enter E or W in addition to the numeric longitude, then don't use - (minus) for west longitudes (if it's even allowed). 'W' and minus are just two ways to indicate the same thing. Similarly for N and S.






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