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#1 Danoglide63

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Posted 22 August 2019 - 08:40 AM

Hello everybody,

 

Last June I became the proud owner of a Celestron AVX EQ mount. The first night I used it I couldn't get it to work right doing the two star alignment. Over and over it was way off! Then suddenly I realized June isn't the 7th month it's the sixth. MYBAD! I don't make that mistake anymore. On my back porch I stretched a string from North to South, placed the correct leg on the string and straddled equally the other two legs. Set the OTA at 34 degrees and wait until Arcturus is visible and then Antares. Then I do 4 star calibration ending with Vega and then I Polar align the mount off Vega since Polaris isn't visible because of the tree.  I marked the location of the legs to save time setting up and it works great every time. Somehow when I go off camping everything turns to poop! I carefully pull my string, straddle the line, etc. set the location on the hand control, time, etc. but when it tries to go to Arcturus it's way off! I usually take advantage of Jupiter being visible and loosen the clutches and manually slew over and double check the finderscope alignment first so that's not the problem. So I start eyeballing Arcturus's location until I get it in view and do the first alignment. Same thing happens with the second star Antares but I keep at it until it's centered. By now there's so many star's when I go to the 4 star calibration I'm guessing I'm right and do the polar alignment. I'm not...if I enter anything in the hand control it's nowhere close! This has happened the last three times I've gone somewhere but never happens here at home. I triple check everything!

 

Can I just go ahead and do the Polar alignment on Jupiter? The hand control allows me to enter Jupiter as a choice. I don't want to blow $300+  on something that will do everything for me.

 

Thanks,

Dano



#2 mbechtel

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Posted 22 August 2019 - 08:56 AM

When you go camping, you should be able to look thru the hole in the RA axis to sight Polaris. That will help. Also, in addition to the time, you should change the location in the hand control to the local longitude and latitude.


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#3 SeaBee1

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Posted 22 August 2019 - 09:23 AM

Dano, it sounds to me like you are doing the right things for your camping alignment. You have set your time and location and have done a passable initial polar alignment with your string (assuming you have it lined up N to S as accurately as possible...). The AVX mount assumes a starting point of basic N to S alignment. If the initial pointing to N isn't close, the first slew to your chosen alignment star will be off, but should self correct as you add calibration stars. This builds the sky map in the hand controller and should put you on target when you complete the alignment process, regardless if the mount is accurately pointing N. If you are south of the equator, then a south polar alignment is necessary, but the steps should be the same.

 

One thing I did to simplify my setup - I bought the GPS device for my AVX. No matter where I set the mount up at, the location and time are accurate.

 

As you have already discovered, being off by one month on your time entry can mess things up. Some other things that can mess things up:

 

Inaccurate location entry

Inaccurate time or DST entry if you cross time zones... and remember, some states do not follow the DST change...

Choosing a star you think is the correct one from a field full of stars in the finder and it isn't the correct star

 

Apart from that, I don't know what else could be causing the mount to be off. Others may chime in with additional things to check...

 

Good hunting!

 

CB


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#4 trapdoor2

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Posted 22 August 2019 - 10:10 AM

The only thing I can think of is that you haven't mentioned levelling your tripod before putting the AVX on the tripod. I have a small 'bullseye' level that I put in my EP case for that. If you're off level, that first alignment star can be off considerably.

 

When I'm out at our Dark Site, I will often add a setup point by aligning my "home" marks and then manually (not with the controller) centering Polaris in the scope (ALT/AZ with the screw knobs). No, Polaris isn't exactly celestial north, but it is close enough. If you're using a compass to set up your tripod, be aware of the compass deviation for wherever you are...some places can be really whacko.

 

I bought a polar alignment scope for it. I'm at 34 and change (alt) and cannot contort myself to be able to see thru the RA axis. Waste of money for me.

 

I also have found that using the alignment stars 'suggested' by the handset tends to get me a better alignment. That works great out at our Dark Site where we have low horizons, 360. At home I have to use what I can see and I get less accurate pointing, even after doing a PA. I've never gone past 2 calibration stars (2 alignment, 2 calibration). 


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#5 Danoglide63

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Posted 22 August 2019 - 10:43 AM

Sorry I forgot to mention leveling, I do level the tripod two ways with a 6" level before I attach the mount. Last night I changed the location from home to one location I thought may be the closest but changed it after checking a map. Then I looked on my iphone compass for the degrees N and degrees W and entered my location that way. I had a street light blinding me when I looked East and had troubling finding Polaris in the sky, I could see the Big Dipper plainly and the two stars in the cup pointing at Polaris but couldn't see it that good. I've tried using my old magnetic compass and two different app's and come up with 3 different readings. If tonight is clear I'll get my mess cleaned up and keep hunting. Bad idea to Polar align off of Jupiter?

 

Thanks everybody!

Dano



#6 Danoglide63

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Posted 22 August 2019 - 11:48 AM

Hmmmm.......could it be that moving to another location requires "Updating your Star Alignment" pg. 30 of the instruction manual?  Undoing the last sync I did at home, redoing the sync at the new location?

 

Sounds good to me,

Dano



#7 SeattleScott

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Posted 22 August 2019 - 01:20 PM

Should just be able to update location. If it is less than 50 miles it won’t really make a difference for visual.
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#8 trapdoor2

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Posted 22 August 2019 - 02:08 PM

My dark site is only 30mi from my house, I've never updated the location between the two. No alignment problems.


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#9 Jon_Doh

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Posted 22 August 2019 - 02:16 PM

If you change locations you need to do a new star alignment to match where you are.  Also, check your handset and determine if it requires you to enter the elevation.  Some do and that might make a difference when you change locales.


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#10 Danoglide63

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Posted 22 August 2019 - 05:53 PM

Last night I was 80 miles from home, the other two times I was 377 and 400 miles from home.  Jon Doh, should I do the "Undo the last sync"?

Thanks,

Dano



#11 SeattleScott

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Posted 22 August 2019 - 06:02 PM

Ok I’m rather confused now. ANYTIME you set the scope up you need to repeat the alignment procedure. The Celestron has the ability to remember the last alignment, which is great when you have it permanently mounted in an observatory. But if you are tearing the scope down, throwing it in your car, then getting it back out and setting it up again, you will need to repeat the alignment procedure. Is that what you mean by repeat last sync or am I misunderstanding?

Scott
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#12 Danoglide63

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Posted 22 August 2019 - 07:27 PM

Ok I’m rather confused now. ANYTIME you set the scope up you need to repeat the alignment procedure. The Celestron has the ability to remember the last alignment, which is great when you have it permanently mounted in an observatory. But if you are tearing the scope down, throwing it in your car, then getting it back out and setting it up again, you will need to repeat the alignment procedure. Is that what you mean by repeat last sync or am I misunderstanding?

Scott

Yes Scott I do the two star alignment, 4 star calibration and PA any bright star every time I set up on my back porch. I did one time "Use the last Alignment" and that worked fine. The "Sync" is the bright star I use since I can't see Polaris. My question is if I don't "unsync" with that star at a new location will the mount thinks it's still on my back porch? Does that make sense?

 

Thanks,

Dano



#13 SeattleScott

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Posted 22 August 2019 - 08:10 PM

You are just doing visual right? Four calibration stars and polar alignment not really required. I usually add one or two calibration stars and just do a rough polar alignment.

Don’t really understand what you mean by syncing on something instead of Polaris, but I never do a polar alignment.

Scott
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#14 Jon_Doh

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Posted 23 August 2019 - 08:31 AM

Last night I was 80 miles from home, the other two times I was 377 and 400 miles from home.  Jon Doh, should I do the "Undo the last sync"?

Thanks,

Dano

Yes, anytime you change locations you need to do a new alignment.  You also need to enter the coordinates for your location and if your unit requires elevation, as some do, input that for your current location.  You can get the gps coordinates from a number of sources on the internet.  Just do a search and input the address.


Edited by Jon_Doh, 23 August 2019 - 08:32 AM.

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#15 Jon_Doh

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Posted 23 August 2019 - 08:34 AM

You are just doing visual right? Four calibration stars and polar alignment not really required. I usually add one or two calibration stars and just do a rough polar alignment.

Don’t really understand what you mean by syncing on something instead of Polaris, but I never do a polar alignment.

Scott

 

Scott,

 

Some hand controllers have a procedure whereby you can sync to a nearby major star if your goto is off quite a bit.  This is supposed to rectify the problem.  I think that's what he's referring to and been doing.


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#16 SeaBee1

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Posted 23 August 2019 - 09:02 AM

Might I suggest the GPS device from Celestron to take all the guesswork out of "Where the heck is my scope located in time and space?" It's not terribly expensive and eliminates the problem to a fine degree.

 

On the issue of "Sync"... this is a NexStar feature that allows you to improve GoTo accuracy during the current session and works best when you are surveying a particular area of the sky, such as looking at all the objects in the constellation Hercules. It has nothing to do with "Syncing to my patio location" and it will be washed out of the HC memory when powered off. It is designed to be effective for the current session only. Therefore, it is not what is causing your poor GoTo's when you go off your home location.

 

I suspect it is a problem with location/time setting, but could be exacerbated by other unrevealed, at this time, setup errors. Which is why I recommend the GPS device... it will eliminate the bane of many setup issues... user data entry error. With that problem solved, the problem may at best be gone, or the solution should become easier to find...

 

Good hunting!

 

CB


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