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Syncing OTA to Go To Mount

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#1 Dmagyar

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Posted 10 September 2019 - 04:44 PM

So new scope/mount figured Go To was best for me...TBD...

 

Anyway received a newly purchased scope with no documentation, which I later received via email (thanks to Kent at ES).   But nonetheless didn't glean that the go to mount has parking for the scope, as you finish for the night, turned it off, (didn't park scope) removed the OTA and went indoors, and off to bed.   

  

The next (second night of ownership) mount the OTA to the mount and dutifully align the arrows on the mount...Now when trying to slew/move to some new star, the computer thinks the OTA is pointing where it would have been had I not done what I did, (see first night). 

 

The good news is that the handheld controller seems to have a RA and Dec reading for where it thinks it's at.  I'm thinking that if I copy the read outs, (to the RA and Dec circle) that's where it was originally and hopefully dovetailing with the computer again.  Any thoughts, (I already know I screwed up) remember I'm new to this...

 

Will be attempting to align with some of the few stars listed tonight barring anything unforeseen, which may fix it anyways...

 

Dan



#2 Alex McConahay

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Posted 10 September 2019 - 04:55 PM

What is the brand/model of the mount?

 

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#3 macdonjh

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Posted 10 September 2019 - 05:00 PM

+1, which mount is it.  Almost every controller I know forgets where it is unless you "park" it before turning it off.  Gemini won't but if you turn the mount controller off, remove the OTA, replace the OTA then start the controller again the chances the mount hasn't moved during all that are pretty small, so it won't point where you think it should.



#4 Dmagyar

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Posted 10 September 2019 - 05:00 PM

It's an Explore Scientific 152mm Mak, with EXOS-2 GoTo German Equatorial mount, I think made by Bresser.



#5 Dmagyar

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Posted 10 September 2019 - 05:03 PM

Reason I think that it's off is that when directed to a star I know to be above the horizon, it says it's below the horizon...Last night trying to align with one star alignment, the stars it directed me to where are below the horizon via my Red Shift star viewer program on my phone.   



#6 jeffreym

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Posted 10 September 2019 - 05:27 PM

Generally, once you shut off the power, you will have to realign the setup.  When you turn the power back on, the computer presumes the setup is in the "home position" and requires you to reset or confirm location, date, and time of day type information (it may be defaulting to the location, date, and time when you powered it down).

 

Just do a new alignment each time you set up.  The more stars you use the better the alignment will be.

 

Good luck,

Jeff 


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#7 Dmagyar

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Posted 10 September 2019 - 06:14 PM

So I'm not getting my point across, I moved the scope after it was shut down, by hand, then with the clock drives, then shut it down prior to "parking"

I get that I'll have to re-align each time I start the scope drives up afterwards. The drives have something that tells the computer where it's pointing, that has to come from somewhere as the scope it's self doesn't have any sensors to note it's location.  That therefore has to come from where the drive motors are in relation to where the scope "should" be pointing.  That's the only reason I can come up with where now when the scope says it's pointing to Spica, and it isn't...Those are apart from where the alignment arrows are.



#8 OldManSky

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Posted 10 September 2019 - 06:42 PM

So I'm not getting my point across, I moved the scope after it was shut down, by hand, then with the clock drives, then shut it down prior to "parking"

I get that I'll have to re-align each time I start the scope drives up afterwards. The drives have something that tells the computer where it's pointing, that has to come from somewhere as the scope it's self doesn't have any sensors to note it's location.  That therefore has to come from where the drive motors are in relation to where the scope "should" be pointing.  That's the only reason I can come up with where now when the scope says it's pointing to Spica, and it isn't...Those are apart from where the alignment arrows are.

Your particular mount doesn't have anything in the drives that tells the computer where it's pointing.  It has simply assumed (wrongly!) that you started up at the same place you shut down.  It knows where it was when you shut down, and it knows how much time has passed -- that's all it knows.

 

Although that situation will be a bit inconvenient when doing a star alignment now, it's not fatal or a problem.  Pick an alignment star, and it will try to GOTO it.  It won't be in the right place.  That's OK, use your finder, and move the mount (using the motor controls on the hand controller, don't loosen the clutches and move it manually) to the star.  Once you do that, the mount will now know where it really is, and you'll be good to go.

 

You'll have to do a star alignment every time you start up no matter what, it's just that if you shut down in a known position (like "home" or "park"), and you start up again in that same position, the mount will be *closer* to the first alignment star.  It might even get it in the FOV (or it might not, depending on your mount's accuracy).  As soon as you move the scope to it and "sync," though, you'll be good to go.  That's the case whether you shut down/started up at "park" or not.

 

Don't worry, you didn't break anything.  It's all good.  Just align and enjoy.


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#9 Alex McConahay

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Posted 10 September 2019 - 06:45 PM

I am not familiar with the mount you are using. 

 

But, in general, I would:

 

Do a manual polar align (using polar scope or whatever).

 

Shut the scope off.

 

Release the clutches so both axes swing freely.

 

Move the scope to the "Home Position." I do not know about your scope, but this is usually with the scope pointing north, and the counterweight down.

 

Tighten the clutches.

 

Now turn on the scope. 

 

Go through your initial celestial alignment procedure. Usually this involves telling it to go to the first alignment star, centering it with the handpaddle, and then pressing "Enter." (or Align or something.) 

 

Then send it to a second star and do the same. 

 

This is usually enough to get an alignment working. 

 

What I have described here is very generic, and more modern scopes may have their own celestial alignment routines. Please follow the one in your scope. 

 

It is not uncommon to have to do this initial celestial alignment every setup (and shutting the scope down, moving it, and so forth, is a new setup). It is even somewhat common in the case of scopes set up night after night in the same place (not as common, but it can happen). It usually only takes re-aligning on one star.

 

By the way, in general, you should not be moving the axes on a mount without loosening the clutches. Most can schmooze right through it. But some suffer excessive strain or wear on the gearing when that happens. 

 

Alex


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#10 Dmagyar

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Posted 10 September 2019 - 06:56 PM

I am not familiar with the mount you are using. 

 

But, in general, I would:

 

Do a manual polar align (using polar scope or whatever).

 

Shut the scope off.

 

Release the clutches so both axes swing freely.

 

Move the scope to the "Home Position." I do not know about your scope, but this is usually with the scope pointing north, and the counterweight down.

 

Tighten the clutches.

 

Now turn on the scope. 

 

Go through your initial celestial alignment procedure. Usually this involves telling it to go to the first alignment star, centering it with the handpaddle, and then pressing "Enter." (or Align or something.) 

 

Then send it to a second star and do the same. 

 

This is usually enough to get an alignment working. 

 

What I have described here is very generic, and more modern scopes may have their own celestial alignment routines. Please follow the one in your scope. 

 

It is not uncommon to have to do this initial celestial alignment every setup (and shutting the scope down, moving it, and so forth, is a new setup). It is even somewhat common in the case of scopes set up night after night in the same place (not as common, but it can happen). It usually only takes re-aligning on one star.

 

By the way, in general, you should not be moving the axes on a mount without loosening the clutches. Most can schmooze right through it. But some suffer excessive strain or wear on the gearing when that happens. 

 

Alex

That's about what I'll be doing tonight, thanks to all.  Dan  



#11 Dmagyar

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Posted 10 September 2019 - 09:09 PM

So a somewhat associated question; with a vixen style mount, the OTA rings on my scope have on one side a stainless plate, which seems to allow the screws for attachment a place to bite, but not leave too many marks, as the other side of the dovetail rail attached to the rings is painted.  When this scope showed up, the rings assembly had the stainless rail side opposite of the aforementioned north, "parked" alignment.  The rings don't have any way of being oriented other than this one side seeming to go towards the screws for the vixen mount...So that's what seems right and what I'll do, swap the ring-handle assembly, pictures to follow to help illuminate part of my initial problem...

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Edited by Dmagyar, 10 September 2019 - 09:37 PM.


#12 Alex McConahay

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Posted 10 September 2019 - 09:48 PM

If you loosen the clutches, can you swing the dec axis all the way around? If so, you can have what was on one side (the gouging screw)  move to the other (the stainless steel side)....

 

(Funny, I just spent an hour drilling and tapping a piece of aluminum shaped like a Vixen Dovetail so that I can move one of my telescopes from my Celestron mount to my Super Polaris without changing the dovetail......Felt good to be back in ATM for a while.) 

 

Alex



#13 Dmagyar

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Posted 11 September 2019 - 10:52 AM

If you loosen the clutches, can you swing the dec axis all the way around? If so, you can have what was on one side (the gouging screw)  move to the other (the stainless steel side)....

 

(Funny, I just spent an hour drilling and tapping a piece of aluminum shaped like a Vixen Dovetail so that I can move one of my telescopes from my Celestron mount to my Super Polaris without changing the dovetail......Felt good to be back in ATM for a while.) 

 

Alex

Alex, your absolutely correct, but what is the purpose of the alignment arrows for, as when in that dec, the arrows on the body of the drive  are not in conjunction, but opposition, to borrow use of a term I read recently....



#14 Alex McConahay

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Posted 11 September 2019 - 11:49 AM

Alex, your absolutely correct, but what is the purpose of the alignment arrows for, as when in that dec, the arrows on the body of the drive  are not in conjunction, but opposition, to borrow use of a term I read recently....

 

 

I dunno!!!!

 

Alex



#15 SeaBee1

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Posted 12 September 2019 - 08:24 AM

I am not sure about the alignment routine your mount follows, but for my AVX, when I power up, it doesn't care where the mount was last pointed... after date/time/location entry, it always tells me to index/align the tic marks and with the mount/scope pointed north, the mount assumes a (rough) polar alignment to start with. This is done with clutches released, and then locked once on the tic marks. The first alignment star slew is rarely spot on center, but never far away.

 

HOWEVER, there is an option to choose "Use Last Alignment", but I think the mount assumes it is "Parked" for this to be successful. I leave mine in "observatory" status (mount stays put on the patio, scope mounted and covered, and I always "park" it), so I tried it once, but it was after MANY days idle, and it did not work as intended.

 

For all practical purposes, a mount doesn't care or need to know where it was last, it only needs to know where it is to start with when powered up. Mine has index tic marks on both axis to ensure the mount knows the starting point. Of course, yours may be different.

 

CB



#16 Dmagyar

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Posted 14 September 2019 - 10:29 AM

After going over what my initial steps were setting up the scope, I had to conclude one very big mistake I did, entered the time in the 12 hour format, completely missing there was no am, pm...I am a beginner, but learning...No wonder the go to was so far off.  Duhhh


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#17 Alex McConahay

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Posted 14 September 2019 - 11:35 AM

And all my good explanations were way off base!!!!

 

Alex



#18 sg6

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Posted 14 September 2019 - 11:52 AM

Park is more applicable to having the scope on a fixed pier in an observatory where the scope is not moved. So the alignment corrections determined one night are the same for the next. Suppose that means if "Parked" the corrections determined are either written to somewhere to be available the next time (NV Ram) or are not cleared out. Wonder which. Guess that Park has a small buffer of data that is accessed the next power up.

 

If the mount/scope is moved then you need to do a new alignment to determine the new corrections that need to be determined and applied. In effect you do the alignment each night.

 

In a way Park causes the assumption that you can align one night and use the previous data the next - reasonable if the scope has not moved at all otherwise misleading.




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