Fails to plate solve via SGP Pro


#1

Hi All,

I’m having a continual plate solving failure when I try to do it using SGP Pro. Both Platesolve 2 and Pinpoint return a fail and although Astrometry.net does find a solution it takes a long time (over 5 minutes). When I access Pinpoint using the Visual Pinpoint interface (with a saved copy of the image) it does find a solution very quickly (a few seconds).

The Dropbox linked files include session log, a sample FITS file and some screenshots.

I’m using an Orion Starshoot G3 colour camera, although this test was done with an image converted to mono - could the image quality be the cause? But then why the discrepancy between Visual Pinpoint and doing it via SGP Pro?

Any help greatly appreciated.

Mike


#2

@Pronto,

For help with plate solve issues we will also need a dropbox link to an example image that is failing to solve. Sounds like it might be bad hint data since both PP and PS2 are very sensitive to it and Astrometry.NET is much more tolerant (depending on how it’s run)


#3

Thanks Ken,

There is a fits file in the linked Dropbox folder - plateSolveTest.fit - of a typical image. I have tried populating the hints with the output from Astrometry.net and Visual Pinpoint and this made no difference.

Mike


#4

Just guessing…check the pixel scale you are shooting at …it must be pretty accurate.


#5

Thanks - I suspected the pixel scale might be an issue. I calculated the scale at 1.87 but both Astrometry.net and Visual Pinpoint give 1.47. I’m not too sure what to make of the difference; accumulation of errors in pixel size, focal length of the scope and the effect of the focal reducer perhaps.


#6

I would think that would be more than close enough.


#7

I just started using platesolve around a week ago

I use platesolve 2’ catalogs, and astrometry.NET for the backup

For the slewing and centering I first get a good PA, and them after entering my RA/DEC in the target details, I click slew. I then click center.

I setup platesolve2 for any DSO image with 2x2 binning, with a 10 sec sub.
I have not failed within 2 min slewing and centering yet.

I did have issues with astrometry at times though a while ago when I first tried using platesolve so I gave up. Platesolve2 has remedied that.
I sometime will slew to a star to focus on first, before the DSO target, and did find that the 10sec was too much and it never solved. I backed the exp down to 1 sec, and it solved 1st try.

maybe this helps
Good Luck


#8

I am not really sure. I cannot get Pinpoint or PS2 to solve it even with exacting hints. It is possible that the presence of a Bayer matrix might throw off some Plate solvers, but both are usually pretty good about that kind of stuff. Astrometry.NET works for me as well and returns this as the location:


#9

That’s interesting and might give me a clue - the Astrometry.net solution I got was quite different from the one you have (although the same as the one using the Visual Pinpoint interface). Mine gave RA = 00:42:41, DEC = +41 06 39 and an angle of 83.55. Scale was about the same though 1.48 versus 1.44.

On the next clear night I’ll pay more attention to focus, try to improve on star & polar alignment and then try a range of exposures at different sky positions to see if image quality is the issue. The Orion StarShoot G3 Colour has a CMYG matrix - so I’ll also try a range of binning options as well.


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