Deep Sky Image Annotation (Not Responding)

[MarMax]

The last two times I've used SharpCap it was with a 50mm DSLR lens, so very wide field. Last night was with 4.1.11754 and the prior session was with 4.1.11648. I'm running a Windows 10 laptop and have not made any configuration changes to my Deep Sky catalogs. I'm attaching two logs from last night.

Everything works fine as long as I don't select Deep Sky Annotation. If selected, it will become non-responsive and then cause SharpCap to quit. I also noticed that the SharpCap plate solving does not work with the 50mm lens. I had to switch to ASTAP to get plate solves. And even with a plate solve the Deep Sky Annotation would be non responsive. Target centering worked without a problem (with a plate solve).

I believe 2-3 automatic error reports were submitted.

[admin]

Hi,

it looks like you are having issues with the amount of processing needed for the custom catalogs when activating annotation - in at least one of the logs it was busy calculating JNOW positions from J2000. How big are your custom catalogs? Can you share them with me so I can test the same configuration?

For the plate solving, if you are using your 294 camera with the 50mm lens then you have a really wide FOV (~20 by 15 degrees). This is larger than the maximum supported by SharpSolve - at this scale issues to do with the curvature of the sky co-ordinate system and potential lens distortions become a significant problem. SharpSolve largely ignores those issues, since it simplifies the mathematics and makes plate solving much faster for the vast majority of people who have a field of view up to about 5-7 degrees or so.

You might find it works if you use ROI to only capture a smaller area (about 1/4 or 1/3 of width and height of sensor) when trying to plate solve using SharpSolve.

cheers,

Robin

[MarMax]

Robin,

Thank you for the reply. I'm attaching a screen snip of the Annotation Catalogs. It looks like I need to delete the HyperLeda18 and PGC-Mag18 files as they must really consume processing. Image annotation did take a few seconds to come up when using it with narrower fields but I did not think it would cripple the Intel i7 laptop.

When doing wide field imaging I'm using the annotation to help frame objects so using an ROI will not work. If ASTAP is solving these wide fields then I many just need to use it with the 50mm/294 or 50mm/2600.

As always, your support is fabulous, as is SharpCap!

[carlomuccini]

PGC-MAG 18 include PGC-MAG17 and PGC-MAG17 include PGC-MAG15
select only the necessary (if necessary the so large database)

Carlo

[admin]

Hi,

yes, you certainly have a lot of data being loaded there - the default catalogs in SharpCap run to about 25000 objects, but I expect you have close to 1 million - perhaps more ... It will certainly slow things down.

I did look into the conversion from J2000 to JNOW that showed up in your log - SharpCap is using ASCOM to do that conversion, and ASCOM uses the SOFA libraries that are highly accurate, but also quite slow for this calculation. Changing to a different approach to calculating this, I managed to get a speed up of nearly a factor of 100 on this particular calculation (at the cost of a couple of arc seconds of difference in the results). I will make that change for the next update, although I doubt the final speed improvement will be anywhere near 100x, as now that the JNOW/J2000 calculation is much faster, it will be something else that is the slowest part.

cheers,

Robin

[Xio1996]

Hi Robin,

Could the use of the faster method or more accurate SOFA method be a configuration option?

I use DSA with JPL minor body data to accurately pinpoint a minor bodies location and are worried this may have some impact on locating faint minor bodies using DSA.

Quite happy to be told it won't

Many thanks.

Pete

[RMSQueenMary]

I had a similar problem. SharpCap would slow down when I annotated. I had a bunch of objects from galaxies, galaxy clusters, and quasars.

[admin]

Hi,

I have left SharpCap using the accurate method where it only needs to do the conversion once (ie GOTO a target, etc), but using the faster method where multiple calculations need to be done (image annotation, etc). I was seeing differences of only maybe 2-3 seconds of arc, which I don't think are going to be a big problem - that's really close to the seeing fluctuation scale (especially here in the UK!)

cheers,

Robin

[admin]

Hi,

this is now hopefully fixed in the new version 4.1.11786 (on the downloads page). Not only was the conversion from J2000 to JNOW causing a slowdown, there was also an issue when a very large number of items (1000s or more) needed to be shown in the lists of 'in view' and 'nearby' objects. This was particularly troublesome in your case because of the large size of the catalogs *and* the large field of view.

cheers,

Robin