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AVX users that move around

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#1 Danoglide63

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Posted 22 August 2019 - 06:15 PM

Hello everybody,

 

I bought my AVX mount in June and have got the star alignment, calibration stars and Polar alignment on the mount without seeing Polaris down pat. I pulled a string N-S with a compass, set one leg on the S mark and split the distance equally between the other two legs. Leveled up two ways using a 6" level before setting the mount in place. Everything works fine here but when I go camping and set up in a new location as near perfect as I can but things go all to snot. I first check the finderscope on Jupiter to make sure it's matching the telescope and then when Arcturus shows up I start the two star alignment. Only...Arcturus is nowhere in the finderscope. After I eyeball it's location and center it up I go to the second star, Antares.....ruh roh, Antares is nowhere close to being in the finderscope so I eyeball it and get centered. By now it's getting dark and I try to do 4 star calibration and I'm not sure at all I'm on the right star, there's so many unlike at home where's there's not so many. I usually go to Vega last and also Polar align there. This has happened three times now, 377 miles from home, 400 miles from home and last night only 80 miles from home. I do change the location on the hand control, double check the time and date. I even looked on my phone's compass where the degrees N and W are shown and tried that. Every object including Jupiter and Saturn are nowhere near in view.

 

I got to looking in the instruction manual and on page 30 I came across how to "Update your star alignment" and "Undo Sync" from the bright star I did the Polar align on any star. This sounds like the cure for my problems but has anybody had the same problem as me and did this solution work for you? If not what did you do to fix the problem? I don't want to blow $300+ bucks on another gizmo to align itself for me.

 

Thanks,

Dano



#2 rajilina

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Posted 22 August 2019 - 07:21 PM

Did you change the latitude adjustment knob on the mount to account for your 80-400 mile difference in location before you start to polar align? Not on the hand control, but via the knob on the mount itself. I rough-adjust the mount in altitude and azimuth via the knobs on the mount after I get the mount balanced and before I start the star align/calibration process.

 

I should edit to add that I’ve found SkySafari very helpful for locating alignment stars in unfamiliar skies.


Edited by rajilina, 22 August 2019 - 07:25 PM.

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#3 SkipW

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Posted 22 August 2019 - 07:31 PM

If you goof up and center the wrong calibration star, everything will be off. Surely you can identify three or four stars to calibrate on. Vega, Deneb, and Altair - the Summer Triangle - are obvious choices currently in the east early in the evening.

 

If you're not sure you can identify the cal star, don't use it.

 

My experience has been that the pointing gets better and better as I add more cal stars when the alignment process has gone correctly. Typically if the fourth one doesn't land in the eyepiece straightaway, I find that the alignment is not good, which means something has gone wrong and it's time to start over. Often the third cal star will be in the eyepiece FOV when it stops slewing, or very close. The alignment stars and first and second cal stars are almost never in the eyepiece when it stops slewing. I use a red-dot finder, so I don't know quantitatively how far off they are, but just driving them to the dot and then centering them in the eyepeice usually works fine. Using a crosshair eyepiece helps make centering the stars quicker and more reliable.

 

Also, skip the polar align step you mentioned at the end. There's no need to routinely do that for visual observing. Just using the alignment stars and three or four cal stars, GoTos will work fine if you did it correctly, even if you get some drift while tracking due to polar misalignment. Only after verifying that your GoTos are accurate do the any star polar alignment, and then only if you really want to.

 

Are you using the AVX's real-time clock, or re-entering the time and date from scratch each time? Does the time zone and DST setting match the time you're entering?

 

Depending on where you are, magnetic north can be quite far off true north, varying from near zero along a line from Lousiana to Wisconsin, up to 16 or so degrees in opposite directions in the far NE and NW of the 48 states. Are you accounting for that? Are you readjusting the polar axis for change in latitude if it's a degree (~60 miles) or more? Have you tried sighting Polaris through the hollow polar axis to get a rough polar alignment, or check a compass-based and latitude-scale one? 


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#4 scopewizard

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Posted 22 August 2019 - 08:02 PM

If all fails and your scope point way off, reset the paddle to default. I had an AVX. I did this procedure, align the index ra and dec, lock them. Try to point the scope within 5 degrees from the pole. First time after a reset, do the 2 stars alignment followed by 4 calibration stars. The next time you setup, same procedure except for calibration stars. The system will only hold 10 calibration stars before it star erasing the oldest one. Alignment stars are for positions while calibration are for refining the movement in some areas of the sky. Hope it help.


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#5 ChuckT

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Posted 22 August 2019 - 08:05 PM

Are you changing the latitude adjustment on the mount each time to match your new location?  That should be the first step after you move to a different location.


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#6 Larrythebrewer

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Posted 22 August 2019 - 11:28 PM

+3 on you have to adjust your latitude adjustment on the mount itself

also your avx doesn’t have gps so you have to input your lat. & long. of your new location
into your hc

Larry
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#7 Danoglide63

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Posted 23 August 2019 - 07:05 AM

Thanks everybody for the quick replies, I use sky safari 6 to tell me things. I think I trusted my location to be set auto so when I looked at the elevation of Polaris it was still showing me the degrees back home so yes I was off 2 degrees. Is the angle finder on the mount accurate or is it off? I usually double check with my iphone. I always wind up moving it anyway when I Polar align. Now it's wait for the sky to clear up here and get ready for next month and go somewhere and see if I can get the change of location correct this time.

 

Thanks again,

Dano



#8 WadeH237

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Posted 23 August 2019 - 07:28 AM

Simple solution to getting the right star in the eyepiece:  Forget the finder scope.  Get a Telrad.

 

I've not used a finder scope in decades, even on my dob, when I do star hopping.


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#9 rajilina

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Posted 23 August 2019 - 12:08 PM

Thanks everybody for the quick replies, I use sky safari 6 to tell me things. I think I trusted my location to be set auto so when I looked at the elevation of Polaris it was still showing me the degrees back home so yes I was off 2 degrees. Is the angle finder on the mount accurate or is it off? I usually double check with my iphone. I always wind up moving it anyway when I Polar align. Now it's wait for the sky to clear up here and get ready for next month and go somewhere and see if I can get the change of location correct this time.

 

Thanks again,

Dano

The latitude adjustment isn't perfect, but it will get you in the ballpark. The other thing to remember is to rough align the azimuth as well. You can't just point the tripod north and then slap the mount on it; you have to make sure the mount is also pointing the same direction as the tripod. If you look under the mount between those two azimuth adjustment screws where the post on the tripod is supposed to fit, there is a lot of room there for you to be off, so rough-aligning there will make a difference. Although my phone has been great for latitude and longitude information I don't use it for finding north because in that regard it isn't entirely reliable; I have an old Suunto compass in my tool box and based on my casual observation it seems to do a much better job.

 

I've found I can usually tell how off I am in rough alignment by where the telescope ends up after slewing to the first alignment star. Once in a while it's better to reset the index markers and fix it, then start the calibration again.

 

I don't often use the polar axis hole in the mount because I can't see Polaris from my backyard, which is where most of my observing takes place. I start aligning at dusk, because only the brighter stars are out which makes it easier to find well known ones for calibration. I usually align to Jupiter first because it's the first bright thing I can see, and I check my finderscope against the OTA at the same time to make sure they are in sync. Then I usually go to Vega, which is hard to miss, and then Altair or Arcturus. By the time those are aligned a few more stars have come out and I'll replace the Jupiter alignment with something else to fine tune it, and add another calibration star or two. By the time this is done, my scope is very nicely aligned and it will put everything nearly into the center of my eyepiece on the first try. If you find you are still a bit off, you can update your alignment stars at any time during your observing session by finding one, then replacing a previously aligned star with it via your handset. The more stars you are precisely aligned with, the better your go-to will be.

 

I was out last night and spent a good two hours looking at various DSOs and this same alignment procedure put them in my eyepiece every time. 


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#10 droe

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Posted 24 August 2019 - 09:42 AM

If you're at a dark site with millions of stars, try selecting double stars to do your calibration. They are much easier to identify. Examples would be like Epsilon 1 Lyrae (the famed double-double) or Albireo in Cygnus. After a few of those your calibration should be close enough for everything else.


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#11 WadeH237

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Posted 24 August 2019 - 01:33 PM

If you're at a dark site with millions of stars, try selecting double stars to do your calibration. They are much easier to identify. Examples would be like Epsilon 1 Lyrae (the famed double-double) or Albireo in Cygnus. After a few of those your calibration should be close enough for everything else.

Epsilon Lyrae is not a great alignment star because you'll get both of the wide pair in the eyepiece at the same time.  It will matter which one you center, and you won't be able to easily tell them apart.

 

Albireo is a good choice, as is Mizar.  But if you follow my suggestion of using a Telrad, it all gets much easier than any finder scope.


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#12 StarBurger

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Posted 24 August 2019 - 08:32 PM

Sorry Wade, can't agree about a Telrad.

I tried it to see how much more comfortable it was to use over a straight 9 X 50 finder (on recommendations from other Telrad users) .

I was persuaded that it was easier to view since my eye would be further back etc. 

Not so. 

Of course I could only see the same bright stars I could see naked eye and somehow with all the squinting, parallax errors and neck cracking it just diminished the experience.

Let's not ignore forgetting to switch off the LED!

Got a right angled 9 X 50 and gave away the Telrad. Not just gave away; paid the USPS $13 to deliver it to a deserving recipient, although I had some guilt about sending such a piece of junk to anyone! Bye-bye dismal Telrad....

So now I use a right angled finder on both SW 80 mm ED and CR 6 and on my 200 mm DOB, a green laser pointer.

Comfortable viewing, cross hairs, a happy neck and back and views to mag 6.

Of course this is a completely subjective experience and I am aware that there are many content Telrad users out there.



#13 WadeH237

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Posted 25 August 2019 - 10:08 AM

The fact that you can see the same stars that you see naked eye is the whole point of the Telrad!

 

The question at hand here is how to make it easier to align an AVX in the field.  The alignment stars that the AVX uses are all very bright stars that are naked eye in all but the most severe light pollution, so it's very difficult to center the wrong star in the Telrad (assuming that you know how a good handful of stars by name, which you should).

 

Another benefit to the Telrad is that once you align it with your telescope, it almost never loses the alignment, even when you remove and re-attach it to the telescope.  This means that for portable use, you can remove the Telrad for packing and transport, and then re-attach it when you get there - and you don't have to worry about re-aligning it.  Once set, if you center the desired alignment star in the Telrad, it absolutely, positively will be the brightest star in the eyepiece.  Every.  Time.

 

This is an ideal situation for alignment and calibration stars.

 

As for the battery, this is a total non-issue.  You can use the Telrad for alignment and calibration, and then switch it off.  In this use case, the batteries will essentially last as long as their shelf life.  Even if you forget to turn it off, they last a ridiculously long time.  I have literally forgotten to turn it off at one star party, and found it still on at the next star party, one or two new moons later - and it was still on and working.

 

As far as using Telrad for star hopping, I suppose that everyone has different opinions on the experience.  But I can say that, in my experience, you are in a very small minority regarding the utility and experience.  There is a strong chance that your guilt was misplaced, and that the deserving recipient who received it really enjoyed it.

 

I can also say that the single most common problem with getting good results with an AVX is aligning or calibrating on the wrong star. I see it happen all the time, and it's almost always because the user couldn't identify the correct star in a finder scope - a problem which is completely cured by the Telrad.  As for using a green laser pointer, that is a non-starter of an idea for me.  Even though it would give me a good experience, it would ruin the experience for any other astronomers in the area.  I have been observing in my back yard, and seen someone else's laser pointer, clearly being used as a finder.  The thing is, that I live on the edge of a green belt of tall forest that is about a mile across.  The person using the green laser pointer could not have been closer to me than that, and still I could see it.


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#14 bmurphy495

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Posted 26 August 2019 - 05:18 AM

I sometimes get wild stuff out of my AVX. It's usually somthing I miss in the hand controller like Daylight savings time vs. standard time, or I forget to update the location. 

 

I found using a Polar Scope has helped me with my initial setup and made the first alignment stars much closer to where they should be. 

 

B


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#15 corax

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Posted 26 August 2019 - 08:34 AM

I've had a couple recent misadventures in misalignment, which can serve as cautionary tales.

 

I discovered that for the last 40 years I've been misidentifying the stars in Ophiuchus: I've shifted the top triangle to the west, so what always I thought was alpha-Oph (Rasalhague) was actually alpha-Her (Rasalgethi). Telling the mount you're at one when you're really at the other does not do wonders for GOTO accuracy.

 

I got a WiFi unit to do scope control with SkySafari. It is unfortunately REALLY EASY to accidentally hit a star in the background that happens to be close to the awful direction arrow buttons on the SkySafari interface. Once you do that, the mount thinks you're aligning to that star instead of your original target.


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#16 Danoglide63

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Posted 29 August 2019 - 03:13 PM

Thanks again,

Last night was the first time I was able to get set up on my back porch. Like the last three times I had a lot of trouble but I have an app that shows degrees and I looked up the altitude of Polaris (+34degrees 49 minutes) and set the mount as so. Made everything a lot easier! I did the two star alignment 4 star calibration and it got so accurate it started putting stars in the center of the finderscope. Did the polar alignment on Vega and actually saw more DSO's than ever before here.

 

Woooo hoooo!

Dano


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