SynScan polar alignment bug

[Steffen]

The polar alignment routine in 3.35 works well, even in the southern hemisphere. You get pretty good alignment very fast. Not sure what Lewis is doing…

Cheers
Steffen.

[LewisM]

Well I never!

For me, when I run PAE, it asks to centre on a star, say Achernar. Fine, off it goes. I centre, and press enter, and all it does it revert to the first screen of the PAE. In other words, it does NOTHING.

I have run the pAE before with 3.33 etc, so know what I am doing, but for some reason, it just is not working on mine. So, I just do the "Lewis Drift Align" - I use 3.28B21. I do a 2 star align, and I observe the MEL/MAZ readout after a successful alignment. I then adjust the mount "by eye" in az and el, and redo the alignment using the same stars. I then do this for several iterations until I am under at least the minute of error (0*00'XX") for both axes. I then check it again as a goto assignment, and if it nails it (which it usually does), I will then slew to a globular or similar and see if it nails that.

I will then run the mount in sidereal for 20 minutes with PHD "live view" on and watch in the autoguider. If the star does not stray (NO GUIDING, just watching with gridlines on), I will then start my imaging for the night

[Astro_Bot]

Firstly, I haven't used the SynScan polar alignment feature yet, so bear with me, but ...

PAE is Pointing Accuracy Enhancement, and it sounds like it's behaving correctly from Lewis's description.

Polar Align is a different feature altogether - it's accessed from the Setup menu, whereas PAE is accessed from the Utility Func. menu.

Could it be as simple as that?

[seeker372011 (Narayan)]

Originally Posted by LewisM

The PA feature of 3.35 when I tried it simply refused to work. It tells you to centre a star, I do, and hit enter, and it goes back to the Setup page all over again. In other words, it doesn't do ANYTHING.

I just drift align. Less frustrating.

B****r. Why, when it works well on Celestron, can they not get to work on the EQ6, I can not understand.

[seeker372011 (Narayan)]

Originally Posted by Steffen

The polar alignment routine in 3.35 works well, even in the southern hemisphere. You get pretty good alignment very fast. Not sure what Lewis is doing…

Cheers
Steffen.

Oh ....

[Steffen]

Originally Posted by Astro_Bot

Firstly, I haven't used the SynScan polar alignment feature yet, so bear with me, but ...

PAE is Pointing Accuracy Enhancement, and it sounds like it's behaving correctly from Lewis's description.

Polar Align is a different feature altogether - it's accessed from the Setup menu, whereas PAE is accessed from the Utility Func. menu.

Could it be as simple as that?

Sounds like it is, just a little PA vs PAE confusion. PAE does indeed work like that. And yes, it works well, too, although I haven't found exactly how big around the PAE star the effective radius is. All the manual tells is that there are some 80+ PAE regions.

PAE has bugs, but they don't seem to interfere with its function when ignored. For some objects, after calling up the PAE function, it doesn't show the object's name. For some other objects (esp some SAO stars) it shows the name of an IC object (always the same IC number, forgot which one).

Cheers
Steffen.

[LewisM]

No wonder it didn't work...

I tells ya, I am getting stupider as I get older. At least my drift alignment works

[chiaroscuro (Luke)]

Should you routinely do this PAE after doing a rough polar alignment and a 1-3 star alignment? (I need to change my username to "Confused beginner".)
Does the software constantly correct alignment errors as you uses it - i.e.. if you dial up an object, and then need to adjust to centre it, does the software integrate this correction for each subsequent object? That would seem like a sensible feature.
I've had a bit of a whinge elsewhere about Synscan firmware being not fit for purpose. The ACCC would be interested in any complaint about a product being sold which cannot perform the function which it is designed for. I'm going to email skywatcher about it.

[Steffen]

No, PAE should not be routinely required.

The pointing accuracy also doesn't depend on how well polar aligned the mount is, only on how accurate the 2- or 3-star alignment was. After doing just a 2-star alignment it also depends on the mount/scope's inherent cone error (the whole gamut of geometric errors hiding under that term).

If you take care with 2- or 3-star alignment (use a reticle eyepiece, be as accurate as you can, enter the time correctly to the second, enter your location as accurately as it lets you) then subsequent GOTOs should be good.

I find PAE useful (and used it sometimes) when hunting for objects that are on the verge of visibility. I want to be sure the object is in the centre of the field before straining my eyes, trying eyepieces, filters etc. So I do a PAE step on a nearby star before going to the faint object.

The hand controller cannot automatically adjust the pointing accuracy after a GOTO and manual correction. It cannot know whether you're centring the object after the GOTO, or just panning around.

Cheers
Steffen.

[chiaroscuro (Luke)]

Originally Posted by Steffen

No, PAE should not be routinely required.

The hand controller cannot automatically adjust the pointing accuracy after a GOTO and manual correction. It cannot know whether you're centring the object after the GOTO, or just panning around.

Cheers
Steffen.

If I was smart, and the synscan software developer, I'd put in an option for this. It seems obvious to me that the accuracy of the "map" in the algorithm would be incrementally improved with each GoTo and centring.

But Synscan needs to learn how to crawl before it can walk.

[LewisM]

Why these days with GPS accuracy so refined that a mount developer cannot automate polar alignment based on GPS coordinates. A GPS will tell you the lat and long, and ergo by the lat and long what the magnetic deviation is to correct for true South/celestial south (but a GPS should be reading true south anyway)

I am sure they will do it eventually, but I cannot see the hold up unless - as I suspect - I know absolutely nothing about this subject (considering for me PAE was PA... d'oh!)

[alocky (Andrew lockwood)]

Unfortunately at the level of precision we are looking for in polar alignment, the geomagnetic field varies too much in time. As well as an accurate map of the local geomagnetic field - available from your friendly government geoscience agency, your computer would also need the IGRF model stored internally. Not so trivial. To get this kind of pointing accuracy also requires a very expensive vector magnetometer.
What's wrong with eq align?
Cheers,
Andrew.

[Steffen]

Originally Posted by chiaroscuro

It seems obvious to me that the accuracy of the "map" in the algorithm would be incrementally improved with each GoTo and centring.

I suppose you'd call them stupid, too, if they messed up pointing accuracy every time you slewed to M65, then panned a bit to fit in the whole triplet That's not to say future SynScan version won't have mind reading abilities Until then we have to live with a few extra button pushes.

Cheers
Steffen.