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Plate Solving - No Luck

Posted: 06 May 2022, 02:48
by JackG
Re: AA8 SP1:

In another post I asked about installing a catalog for plate solving. Bill kindly explained how to install GaiaComp, which I did. I not longer get an error message when loading the star atlas.

But plate solving nearly never works. I've been banging my head against this for months. I took the following picture of the field near Arcturus (which is in the upper left corner) and plate solve fails: My plate solve parameters are: If I set the horizontal field to 60 minutes +- 50% it fails. I've tried this with and without the vertical flip. This is with a C8 and F6.3 focal reducer so the field of view is around 60'.

Here's a field around M51 with lots of stars. It fails, too:
I must be missing something simple! Any thoughts? Thanks in advance.

Re: Plate Solving - No Luck

Posted: 06 May 2022, 03:05
by Iver
AA needs a hint at where the scope is pointing. Click on the small icon next to the search region window to load the Ra and Dec from the image.

As I mentioned in your original post plate solve data is separate from the Sky Atlas data.

For more info read this thread.
viewtopic.php?f=3&t=621

For me AA plate solve is less then 1 sec.

Re: Plate Solving - No Luck

Posted: 06 May 2022, 03:27
by Dunmunro
JackG wrote:
06 May 2022, 02:48
Re: AA8 SP1:

In another post I asked about installing a catalog for plate solving. Bill kindly explained how to install GaiaComp, which I did. I not longer get an error message when loading the star atlas.

But plate solving nearly never works. I've been banging my head against this for months. I took the following picture of the field near Arcturus (which is in the upper left corner) and plate solve fails:
Arcturus.jpg

My plate solve parameters are:
Arcturus - PS.jpg

If I set the horizontal field to 60 minutes +- 50% it fails. I've tried this with and without the vertical flip. This is with a C8 and F6.3 focal reducer so the field of view is around 60'.

Here's a field around M51 with lots of stars. It fails, too:

m51.jpg
I must be missing something simple! Any thoughts? Thanks in advance.
Which camera are you using? If you click on the '?' button beside the horizontal field info, it will provide a calculator to set the estimated field width. Is the mount being controlled by AA8 via ASCOM?

The catalog for platesolving is preinstalled ( astroar8.dat ). You can use M and NGC numbers to designate platesolving targets, but it's best to have AA8 controlling the mount so that it can read the approximate target location from the fits header.

Re: Plate Solving - No Luck

Posted: 06 May 2022, 13:44
by JackG
Thanks, Dunmuro. I have had little luck with AA8 controlling the mount or plate solving off-line with no telescope hooked up.

Things are just... weird. For instance, it did successfully plate solve for an image of M51 if I told it to look for M51. On the same image if I give the center search region of 12 +46 (note that M51 is really at 13 30 +47 12) it also solves "successfully" (no error message). But if I click on a star near M51 it says the star is at 11 57 +45 57 (see pic), which can't be right: When I tell it the center search region is M51 it reports the same star at 13 29 + 47 10, which is much more reasonable.

If I tell it to solve at a center region of 10 +44 with a size of 50 50 it does not error. The same star is reported at 11 31 +52 53. It's as if the plate solution is somehow a function of the entered data, not the actual location of things in the sky.

I am rather lost. Any help is greatly appreciated.

Jack

Re: Plate Solving - No Luck

Posted: 06 May 2022, 15:41
by Iver
"I must be missing something simple! Any thoughts? Thanks in advance"

After you make a change in the parameters
settings do you click on "Save Parameters"?

Re: Plate Solving - No Luck

Posted: 06 May 2022, 16:55
by JackG
Iver,

Yes, I did save - you can see that button is greyed out in the picture above.

Jack

Re: Plate Solving - No Luck

Posted: 06 May 2022, 17:23
by AstroBernd
I did have issues with plate solving a few months ago as well. See also viewtopic.php?f=3&t=637
The resolution came when having the horizontal field well defined with just a few % (<10%) variation allowed. 20% or even 50% as I can see in your screen shots has been way too large for me.
Therefor, the calculation of the horizontal field is crucial. And then Reduce the variation allowed to well below 10%!
I also have the orientation and scale markers turned on in my images, so i can directly recognize if something in the plate solve is weird. Since then, plate solve is fast, reliable and spot-on. I even use it to correct the goto of my mount as well. Very neat and fast!
Hope this helps
Good luck
Bernd

Re: Plate Solving - No Luck

Posted: 06 May 2022, 17:51
by fabdev
On the same image if I give the center search region of 12 +46 (note that M51 is really at 13 30 +47 12) it also solves "successfully" (no error message).
Hi, a tolerance of +- 50% with only 5 stars may cause false positives. I suggest to reset the tolerance to the default value of +- 20%.
Actually after you measured the actual field of view, for example with the Statistics window, enter the exact value of the field and reduce the tolerance to +- 2% or +-5%, unless you are using a zoom lens.
Clear skies, Fabio.

Re: Plate Solving - No Luck

Posted: 06 May 2022, 18:15
by Dunmunro
JackG wrote:
06 May 2022, 13:44
Thanks, Dunmuro. I have had little luck with AA8 controlling the mount or plate solving off-line with no telescope hooked up.

Things are just... weird. For instance, it did successfully plate solve for an image of M51 if I told it to look for M51. On the same image if I give the center search region of 12 +46 (note that M51 is really at 13 30 +47 12) it also solves "successfully" (no error message). But if I click on a star near M51 it says the star is at 11 57 +45 57 (see pic), which can't be right:
ps - m51.jpg

When I tell it the center search region is M51 it reports the same star at 13 29 + 47 10, which is much more reasonable.

If I tell it to solve at a center region of 10 +44 with a size of 50 50 it does not error. The same star is reported at 11 31 +52 53. It's as if the plate solution is somehow a function of the entered data, not the actual location of things in the sky.

I am rather lost. Any help is greatly appreciated.

Jack
Again, which camera are you using?

Re: Plate Solving - No Luck

Posted: 06 May 2022, 18:33
by JackG
Thanks, everyone. I'm getting better solutions on photos from days ago using your suggestions, especially narrowing the +/- tolerance. Rain and clouds for the next few days but I'm looking forward to trying it with the telescope again.

Overall: AA8 is marvelous and I've really enjoyed processing images with it.