Goto issues after alignment - AZEQ6 and Synscan Pro + Skywatcher Wifi

[jam1e1]

hi 

got an issue where on multiple nights my goto is way out in AltAz mode, by around 1/2 width of 10x50 finderscope. When i first got the Wifi dongle, it was really accurate after alignment i.e. goto would be within say 12mm eyepiece or very near. Now, over the past few months ive had issues every night despite following guidelines in the manual. Welcome any ideas to help troubleshoot / solve?

Setup summary:

- AZEQ6 mount in AZ mode, ground is perfectly level and I start alignment in AZ of Polaris (ie north) and Alt zero degrees, calibrated via setting circle 

- power supply is mains Nevada PS-08 6-8A Regulated Linear Power Supply so dont think thats the issue

- synscan wifi dongle

- IOS latest and Synscan pro app + skysafari pro

Procedure

- turn all devices on and set AltAZ mode in Synscan pro

- ive tried both north level alignment (usual mode) and brightest star, both exhibit same issues as below

- pick two good alignment stars within spec as per manual e.g. Algol (28 alt and 58 az) and Scheat (55 alt and 119 az) , around a month ago Scheat (39alt and 91 Az) and Altair (46Alt and 160Az)

- align using 9mm reticle with red led for accuracy, using the up and right to ensure no backlash

- it says alignment successful

- i then slew to say Caph and accuracy is way out like 1/2 width of finder, not even near in EP

Welcome any help as ive tried deleting all apps, reinstall, multiple nights different stars and no luck

thanks

Jamie

- 

Edited October 2, 2021 by jam1e1

[Dr_Ju_ju]

First off forget issues with the wifi dongle, as that's just an interconnect device, so I would then suspect that the software you are using, is storing some alignment points, and these are disagreeing with the current data hence the discrepancy.

Uninstalling/reinstalling may well not be removing these stored files, so you may need to look for a separate data folder... 

[Zermelo]

Before you do alignment, is anything listed in "Align">"Align with Sync" ?

[jam1e1]

thanks both, ive cleared out all settings (hopefully) from the Synscan Pro app so will see how it goes tonight. Its not the most stable app, nor is it straightforward to clear stuff out. Will update once had another go!

[jam1e1]

On 02/10/2021 at 10:40, Zermelo said:

Before you do alignment, is anything listed in "Align">"Align with Sync" ?

not now that ive cleared everything out- there was some junk/malformed data in there before and the delete buttons dont seem to work they just duplicate the star and proliferate obscure character additions - seems a very buggy app

[Zermelo]

3 hours ago, jam1e1 said:

not now that ive cleared everything out- there was some junk/malformed data in there before and the delete buttons dont seem to work they just duplicate the star and proliferate obscure character additions - seems a very buggy app

Ah, it used to do that for me too, but not now - I can delete whatever is in there.

You're on iOS, so I assume you don't have the same issue that Android users have with the Synscan  version (latest version on the Android app store is two years behind the one on the SW website).

Have you checked that you have flashed the latest motor control firmware to the mount? (3.14 for the AZ-EQ6)

Edited October 3, 2021 by Zermelo
formatting

[jam1e1]

thanks yes, its the latest firmware. Had the same problem again last night, also noticed the stars would drift a bit over time which is only really noticeable in a reticule. Bit stuck as what to do next! However, reading on other forums and this one it appears there are some threads with similar issues ....

Edited October 4, 2021 by jam1e1

[Zermelo]

3 hours ago, jam1e1 said:

noticed the stars would drift a bit over time which is only really noticeable in a reticule

On the levelling aspect, do I understand correctly that your approach is that your ground is level, so you set up by extending the tripod legs to maximum and setting the mount to horizontal with the setting circle? Have you tried putting a spirit level on the OTA itself (in two perpendicular directions) to confirm that? It was only when I did this myself that I realiized I couldn't assume anything about the spatial relationship between my tripod head and mount, or the accuracy of the alt scale zero mark. I appreciate that your mount is several times the price of mine, but it might be worth checking. I've read a lot of discussion about whether or not accurate levelling is really necessary, given that Synscan should be using your star alignment to calibrate its internal sky model for each session. But I did notice better results when I changed my levelling procedure. And if my goto is inaccurate on a particular session (probably because I'd set up after dusk and couldn't see properly), I usually find that it's consistently so, for different targets - to the extent that I sometimes just make a mental note of the offset in the finder and adjust subsequent operations manually, without trying to correct the mount's sky model with a PAE. That suggests to me that goto inaccuracies are reflecting any inaccuracies in my setting up, rather than resulting from some more random lack of precision in the software or mount.

Have you tried doing PAEs when you have goto problems (i.e. after a goto, make the adjustments to centre the object, and confirm)? Some people have found it necessary to do this, especially if viewing an object that's a long way from the initial alignment stars.

Another thing I've noticed with Synscan (and/or my mount) is that goto accuracy and tracking accuracy in any particular session don't always go together. So, I might find that it will keep an object centred at 300x for several minutes, yet the initial goto for that object might have been half a degree out. Conversely I might be having a particularly good night for gotos, but tracking may not be great. An interesting point there is that if I use repeated, small slews to keep an object in view then it will continue to drift. But if I let it drift and don't bother nudging it, but I then just issue another goto after it has drifted off, it will centre again and usually stay there. It seems that Synscan "knows" that the object is drifting, but can't correct it without a goto (the other alternative would be that Synscan thinks it is moving the axis motors correctly to track the object, in which case I assume that issuing a repeat goto should have no effect - because it believes the object is still centred). I don't know if any of this tallies with your experiences?

 

[jam1e1]

On 04/10/2021 at 14:33, Zermelo said:

On the levelling aspect, do I understand correctly that your approach is that your ground is level, so you set up by extending the tripod legs to maximum and setting the mount to horizontal with the setting circle? Have you tried putting a spirit level on the OTA itself (in two perpendicular directions) to confirm that? It was only when I did this myself that I realiized I couldn't assume anything about the spatial relationship between my tripod head and mount, or the accuracy of the alt scale zero mark. I appreciate that your mount is several times the price of mine, but it might be worth checking. I've read a lot of discussion about whether or not accurate levelling is really necessary, given that Synscan should be using your star alignment to calibrate its internal sky model for each session. But I did notice better results when I changed my levelling procedure. And if my goto is inaccurate on a particular session (probably because I'd set up after dusk and couldn't see properly), I usually find that it's consistently so, for different targets - to the extent that I sometimes just make a mental note of the offset in the finder and adjust subsequent operations manually, without trying to correct the mount's sky model with a PAE. That suggests to me that goto inaccuracies are reflecting any inaccuracies in my setting up, rather than resulting from some more random lack of precision in the software or mount.

Have you tried doing PAEs when you have goto problems (i.e. after a goto, make the adjustments to centre the object, and confirm)? Some people have found it necessary to do this, especially if viewing an object that's a long way from the initial alignment stars.

Another thing I've noticed with Synscan (and/or my mount) is that goto accuracy and tracking accuracy in any particular session don't always go together. So, I might find that it will keep an object centred at 300x for several minutes, yet the initial goto for that object might have been half a degree out. Conversely I might be having a particularly good night for gotos, but tracking may not be great. An interesting point there is that if I use repeated, small slews to keep an object in view then it will continue to drift. But if I let it drift and don't bother nudging it, but I then just issue another goto after it has drifted off, it will centre again and usually stay there. It seems that Synscan "knows" that the object is drifting, but can't correct it without a goto (the other alternative would be that Synscan thinks it is moving the axis motors correctly to track the object, in which case I assume that issuing a repeat goto should have no effect - because it believes the object is still centred). I don't know if any of this tallies with your experiences?

 

hi yes so level with spirit level thanks. 

Agree on offset approach, also use this at times when it is consistently inaccurate! 

Ive done local alignments too when it allows - ie often says too far from centre even though in near FoV!!

also similar on inconsistency with goto and tracking, some nights will stay bang on, come back 20m later fine. other nights moved like the other night as left saturn on rim of EP and moved in like 2mins. Also found depending on if use small or big movements it can sometimes drift then stop, other times not drift at all. Still lost for a solution unfortunately 

[Zermelo]

53 minutes ago, jam1e1 said:

Ive done local alignments too when it allows - ie often says too far from centre even though in near FoV

Ah, isn't that when you do it from SkySafari, though?  SkySafari has the ability to hold a per-session offset from Sysnscan's sky model, if Synscan is off. I don't really use that facility, but I have seen the error message you described, when I tried to correct "too much" on a night when Synscan was a long way off. I've never used it enough to find out just what its limits are.

What I was referring to with PAEs was the Synscan facility - if at any time you choose "named star" and do a goto, and you immediately centre the object manually and confirm it (just as with the initial alignment), Synscan refines its model with the new information (you can see the new object added to the list in the alignment menu). In principle, if you've set up as methodically as you have done, and aligned with a "good" pair of stars, you shouldn't need PAEs. But the instructions say that you can improve the goto accuracy in an area of sky that's far from the original alignment stars by doing a PAE on a local star first.

Apologies if you know all of this already. It's a bit of a mystery.

53 minutes ago, jam1e1 said:

saturn on rim of EP and moved in like 2mins

Now, another thing I've noticed is that I am having more tracking problems with Saturn and Jupiter than other objects. The scope seems to drift downwards (altitude only - azimuth stays tracked). Possibly the clutch is slipping and it's nothing to do with Synscan. I need to experiment a bit more to see if it's happening with other objects that are as low down.

Edited October 6, 2021 by Zermelo
typo

[jam1e1]

15 minutes ago, Zermelo said:

What I was referring to with PAEs was the Synscan facility - if at any time you choose "named star" and do a goto, and you immediately centre the object manually and confirm it (just as with the initial alignment), Synscan refines its model with the new information (you can see the new object added to the list in the alignment menu). In principle, if you've set up as methodically as you have done, and aligned with a "good" pair of stars, you shouldn't need PAEs. But the instructions say that you can improve the goto accuracy in an area of sky that's far from the original alignment stars by doing a PAE on a local star first.

Apologies if you know all of this already. It's a bit of a mystery.

 

Brilliant thanks ill give that a go too  No i didnt realise - very useful! Its odd that it did work fine for a bit without need for extra PAE etc.... although i do recall a while ago picking two stars that were great for a few nights, when changed pairs a couple of weeks later it was way off.

Let me know how you get on with findings - yes i think planets can be more challenging for tracking vs other objects - mine definitely went down but cant remember if AZ affected too. One thing i did notice was Skysafari was also tracking the movement so it shouldnt have been clutch issue for me (i hope at least!)

Edited October 6, 2021 by jam1e1

[Zermelo]

2 minutes ago, jam1e1 said:

Skysafari was also tracking the movement

Yes, that's what I see too. But Skysafari is getting the pointing info from Synscan, so Synscan must "know" that it's lost the object too, but it can't/won't recover. Unless that is, as I said in the previous post, I issue a repeat goto (from SkySafari, easy to do as the object is still currently selected), and then it seems to recover. Even if the clutch is slipping, it's possible that the encoders can still keep track of where it is. I suspect that the goto repeat may be successful, even when the tracking isn't, because goto slews at a higher speed (at least it does when the target's drifted a fair way off), so the innards re-engage. And maybe (guessing now) the "jolt" of the goto slew may cause the clutch to continue to behave itself for the slower tracking duty.

I have a link to a thread where someone takes apart my mount model to tighten the clutches, so if this cloudy weather keeps up I may get brave.