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Help with Mount Slewing to Target

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#1 svsalako

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Posted 04 December 2020 - 08:27 AM

Hi --

 

Brand new astro photographer here. I have had a couple of successful sessions with my EQ6R Pro, At72ED2 using NINA and PHD2 for control. Last night, however, I could not get the telescope to point at a target. Here's what I was doing:

 

--powered everything up

--connected camera, guide scope and guiding, mount in NINA

--selected a target using the sky atlas

--hit "select for framing assistant"

--hit slew

 

Here's where things went wrong. The telescope would move, but it pointed in completely the wrong directing. I tried to plate solve, using different exposure lengths, but they all failed.

 

In my previous imagine session, the rig had crashed in the middle of the session because my computer battery died, so when I checked on it the computer was dead, and the mount was just pointing at where the target used to be. So in my session last night, I tried to return to the home position using the park command, but it did not return to the correct home position -- it just went somewhere random.

 

So I guess my question is how do I get the mount re-oriented so that it knows roughly where it is pointing. I think the plate solves are failing because it is so far off the target.

 

All replies and suggestions greatly welcomed! I need to fix this because last night was the first clear sky I've had here in Vermont in almost 2 weeks, and I wasted it.

 

thanks,

 

Grey

 



#2 alphatripleplus

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Posted 04 December 2020 - 08:53 AM

As you are using an EQ6 there may be some useful tips in this topic.



#3 southerndandy

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Posted 04 December 2020 - 09:04 AM

I use NINA and PHD, and a Sirius mount.  You might need to reset your mount's home position if it's not going to the proper position when you tell it to park.  Also, when I start a session, after getting everything connected I do a plate solve before I slew anywhere so the system knows basically where it is.  Then I'll slew to a target, usually a bright star for focusing.  A lot of the times it's not centered, so I'll do another plate solve just where it's currently pointing.  It's usually pretty close, I'll hit slew to the star again and it centers it.  As far as settings, I do a 5 to 10 second exposure at iso 800 (I use a DSLR).  I'd also say to make sure nothing got messed up with your plate solver directory and make sure your time/date/location are all correct.     



#4 Wookiee

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Posted 04 December 2020 - 09:55 AM

Including plate solving into your routine will save you so much time and frustration aligning targets.

There's multiple options with N.I.N.A but I opted for AllSky (first one I tired and it worked so stuck with it). After polar alignment, I slew to a star under the focus assist option and from there I can check focus and plate solve to ensure the mount is accurately aligned. After moving to my actual target I'll plate solve again an re-slew just to ensure the target is within tolerance and matches closely with the framing assistant.

Although this can all be automated if you have the plate solving enabled and select slew to target and centre target under your sequence options, it'll even realign after an auto meridian flip. N.I.N.A will loop this process step until the target is within your preferred tolerance.

 

Anytime I've turned the mount off at a position other than home I've had alignment issues (pre plate solving). Turning it off and releasing the clutches to manually move it back to home before turning it back on solved it for me. 


Edited by Wookiee, 04 December 2020 - 10:30 AM.


#5 SnowWolf

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Posted 04 December 2020 - 05:24 PM

Hi --

 

Brand new astro photographer here. I have had a couple of successful sessions with my EQ6R Pro, At72ED2 using NINA and PHD2 for control. Last night, however, I could not get the telescope to point at a target. Here's what I was doing:

 

--powered everything up

--connected camera, guide scope and guiding, mount in NINA

--selected a target using the sky atlas

--hit "select for framing assistant"

--hit slew

 

Here's where things went wrong. The telescope would move, but it pointed in completely the wrong directing. I tried to plate solve, using different exposure lengths, but they all failed.

 

In my previous imagine session, the rig had crashed in the middle of the session because my computer battery died, so when I checked on it the computer was dead, and the mount was just pointing at where the target used to be. So in my session last night, I tried to return to the home position using the park command, but it did not return to the correct home position -- it just went somewhere random.

 

So I guess my question is how do I get the mount re-oriented so that it knows roughly where it is pointing. I think the plate solves are failing because it is so far off the target.

 

All replies and suggestions greatly welcomed! I need to fix this because last night was the first clear sky I've had here in Vermont in almost 2 weeks, and I wasted it.

 

thanks,

 

Grey

Tell the mount to PARK and then, by releasing the clutches, point the scope at the PARK position. Now the mount and scope are in agreement. They got out of agreement when things crashed.

 

Also, make sure both NINA and the scope are in agreement about location and time.


Edited by SnowWolf, 04 December 2020 - 05:24 PM.


#6 Alex McConahay

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Posted 04 December 2020 - 09:30 PM

Most mounts assume that when they are first turned on, they are in the home position (usually north, counterweight down). Yours was not. It was wherever it was  left the when your battery died. It was precisely going to wherever you sent it, assuming it was starting at home position. But since you were not at home to start, it looked like it was going goofy. 

 

As has been pointed out, you just need to return it to the home position before turning it on. 

 

Alex



#7 KLWalsh

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Posted 04 December 2020 - 11:27 PM

I had problems recently with my Celestron CGEM mount losing power due to a loose plug.
I found the best thing to do was use the NSEW buttons on the hand control to return it to Home Position, then cycle power and check alignment doing a 1 star alignment.
YMMV

#8 idclimber

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Posted 05 December 2020 - 01:26 AM

A couple things any mount/computer will need to accurately point. The first is latitude and longitude. This is super easy to mess up as it there are a couple ways to express the latitude/longitude coordinates. There is a difference between decimal degree and degree-minutes-seconds. It is also super easy and common to enter east instead of west. Sometimes that is expressed negative or positive. The same is true for North South. Double check this according to the manual. 

 

The second thing it needs is an accurate time. This can also be expressed in different ways. Usually the computer OS can look up time. Some mounts require you to enter UTC time and that is either positive or negative. Get it wrong and it won't align. 

 

The last thing the mount needs is too orient where it is pointed along both axis. Some mounts do this with a homing position and that simplifies alignment. Otherwise you have to go through an alignment procedure. 



#9 svsalako

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Posted 10 December 2020 - 06:25 PM

Hi All --

 

So I am still having the same problem. I have tried the suggestions above ie manually returning to the park position but the  mount still does not slew anywhere close to the selected target, and I cannot plate solve, which worked perfectly before. I was able to use Sharpcap to polar align and I noticed that the "center RA" and "center DEC" numbers were COMPLETELY different that what EQMOD was displaying. So, I think the mount thinks it's pointing somewhere very different from where it is actually pointing.  So, how can I reset the encoders or re-align the mount so that it is oriented?

 

Thanks in advance for any answers. Tonight is the first clear night here in about 10 days and I can't do anything!

 

Cheers,

 

Grey


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#10 Alex McConahay

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Posted 10 December 2020 - 06:49 PM

If you point the mount to a star To the equator/meridian, will it properly track?

Alex

#11 RogerM

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Posted 10 December 2020 - 08:03 PM

There was a thread with what vaguely sounds like a similar plight.  Turned out the fellow had changed some setting to Southern Hemisphere.  Sorry I can't recall any more specifics than that.



#12 Alex McConahay

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Posted 10 December 2020 - 08:43 PM

Yeah, that’s why I am asking if it tracks properly.   If it does, we can eliminate a lot of goofy things 

 

Alex 



#13 svsalako

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Posted 10 December 2020 - 09:25 PM

So here's a follow up:

 

I plugged in the hand controller and successfully did a one star alignment.  However, that had no effect once I plugged the rig back into NINA and EQMOD. There is still a discrepancy between what EQMOID says for DEC and RA, and what it ought to show. The first screen print I've attached shows what NINA thinks is the telescope position when it is in the home position, which is pointing basically right at the celestial north pole. The 2nd screen print shows the error messages after plate solving failed. Here are the screen prints:

Attached Thumbnails

  • home positioin.png
  • plate solve.png

Edited by svsalako, 10 December 2020 - 10:29 PM.


#14 svsalako

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Posted 11 December 2020 - 12:44 PM

Yeah, that’s why I am asking if it tracks properly.   If it does, we can eliminate a lot of goofy things 

 

Alex 

Hi Alex, Yes, the mount tracks. I know because I took a rando pic and there were not star trails.

 

Cheers,

 

Grey



#15 svsalako

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Posted 11 December 2020 - 12:52 PM

So I realize those screen prints are hard to read. There are two things in them that I don't understand:

 

1) The home position of the telescope is basically pointing at the NCP. The RA is basically correct, but the Dec is -8 20, when is should be around +89

 

2) The error message from NINA after the plate solve fails is "ASTAP -- Star data base limit was reached 64x" . I'm not sure what that means.

 

In the meantime, this morning I uninstalled and reinstalled ASTAP and the g17 database, just in case something had become corrupted.

This evening, if I can see stars, I will make sure that the camera is precisely focused and experiment with different exposure lengths to try to get plate solving working.

 

If anyone has any thoughts about items 1 and 2 I'd love to hear them, or any other suggestions. The situation is very strange because the system worked perfectly until I left it out too long and the computer died before completing it's sequence.

 

thanks!

 

grey



#16 Alex McConahay

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Posted 11 December 2020 - 01:22 PM

The fact that it tracks says you have the direction the right way, and that you have the right hemisphere, right motor speeds, and so forth. 

 

The observation that your "Home position" is -8 20  could certainly be a source of your problems. 

 

Is it possible to go to a known, bright star, and synch to that known position. Then go to another (without GOTO), and synch to that. How does that affect the process?

Alex



#17 MSFFT

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Posted 11 December 2020 - 01:41 PM

As Alex mentions, the Dec home position being off by such a large value is likely to throw things off, especially when you appear to be off by 90 degrees. Definitely sort that out.

Separately, if you’re having issues with plate solving and related slewing, try this: from the home position, pick a star near the pole then solve: say Kocab (assuming you’re Northern Hemisphere). The small offset from Polaris should mean that even if the mount skewed 180 degrees the wrong direction and therefore plate solve has a poor initial guess, it should be close enough to finish the solution in a reasonable amount of time.

From there you can slew to and solve another nearby bright star or two and you should be good from there.

I’m always wary of solving while pointing directly at the NCP since small deviations in pointing can show up as huge angle errors that may throw off the mount model.

Best of luck!

#18 kathyastro

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Posted 11 December 2020 - 02:02 PM

You aligned the hand controller.  But then did you unplug it and connect to EQMOD?  That's what it sounds like. 

 

EQMOD and the handset have different goto systems.  They don't necessarily talk to each other.  So aligning one and not aligning the other could cause your symptoms.  EQMOD would either be completely unaligned, or it might have inherited an old alignment from the previous session.

 

The mount head just contains the motors and drivers.  It does not know any coordinates.  Those are all either in the handset or in EQMOD.  So unplugging the handset would unplug the alignment you just did.

 

If you intend to use EQMOD for the session, then do your goto alignment using it.



#19 idclimber

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Posted 11 December 2020 - 02:04 PM

I have a suggestion that has not been mentioned. It seems clear to me that either your mount is broken or more likely some software setting or procedure is eluding you. Fixing this at night is probably not easy and it is not necessary. You can trouble shoot this problem in the daytime and even inside.

 

Setup the mount reasonably close to polar aligned. Use an iphone or tablet with one of the astronomy programs like Sky Guide that can show you where alignment stars are roughly located at. You can even attempt to align on the sun as long as your scope is not mounted. Since your errors are huge you just need to figure out what is preventing you from syncing. it should be obvious when it is finally roughly point east or west. 



#20 svsalako

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Posted 11 December 2020 - 05:20 PM

One thought: is there any way to manually input RA and DEC into EQMOD? I know roughly where the mount is pointing when it is parked -- is there anyway to input those values?

 

Thanks!



#21 nate9862

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Posted 11 December 2020 - 07:30 PM

Hi All --

So I am still having the same problem. I have tried the suggestions above ie manually returning to the park position but the mount still does not slew anywhere close to the selected target, and I cannot plate solve, which worked perfectly before. I was able to use Sharpcap to polar align and I noticed that the "center RA" and "center DEC" numbers were COMPLETELY different that what EQMOD was displaying. So, I think the mount thinks it's pointing somewhere very different from where it is actually pointing. So, how can I reset the encoders or re-align the mount so that it is oriented?

Thanks in advance for any answers. Tonight is the first clear night here in about 10 days and I can't do anything!

Cheers,

Grey


I've been having this problem recently, too, with my EQ6-R but using APT. Sometimes when I park my scope, or try to slew to an object after my mount was disconnected or power cycled, it'll point in an obvious wrong direction. Here's what I've learned..

Once this happens once, just shut the mount off and UNPLUG the USB cord. Then, disconnect Phd2 and APT/NINA from the scope. I also just close APT. THEN, USING CTRL-ALT-DEL, I kill eqmod.exe. I manually put the scope back in the home position, then plug everything back in and start eqmod. You can tell instantly if it worked because EQMPD will correctly show the right RA/DEC coordinates.

What I think happens is APT or PHD2 holds the previous scope position in memory and when the mount is power cycled, EQMOD considered it parked in the home position, but APT or PHD2 syncs it's last known mount position to the mount and eqmod.

It's very frustrating, but it's the only process that works for me every time. After I re-cycle everything I just slew and plate solve and I'm back in business. Takes only 5 mins now.

#22 svsalako

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Posted 12 December 2020 - 09:04 AM

OK Problem solved.

 

I did the following:

 

--powered up mount and eqmod

--parked, then unparked via eqmod

--powered off mount

--shut down eqmod

--manually positioned mount in home position

--powered up mount

--powered up eqmod

 

The first clue that this was going to work was that the RA and DEC of the home position now makes sense. I was then able to use the manual focus aid in NINA to slew to Deneb to focus. Plate solving worked as it should in that position. I then used to NINA to select M33 as a target and the mount slewed to that position, plate solved, centered, plate solved again and that was that.

 

The only fly in the ointment is that my ASI120mm guide cam failed right as I was setting up the imaging sequence. But I still was able to take 60 120 sec. exposures just using the tracking from the mount. Fortunately, the 120mm is still under warrenty !

 

Thanks for all the help and support.

 

Cheers,

 

Grey


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