Polar Alignment - what is causing it to fail?

[DrAstro]

I'm attempting to polar align a mount.

Details:

OTA: Meade 14" STC working at EFL of 2184mm
Camera: QHY174GPS - EFOV 18'x11'
Mount: Bisque Paramount ME

During the attempt to polar align, I moved the scope to ~3h RA and +88 DEC. This is well within the ~5 degrees from the pole recommendation.
I adjusted the exposure/gain and the polar alignment status showed that it was finding 20-30 stars and was using 15.
The dreaded red "Could not solve" continued to be displayed.

While in polar alignment, I went to tools/Plate Solve (solve only) and instantly it returned a solution. I selected SharpSolve as the plate solver. I repeated this over and over and it never failed.

With this in mind, why can't the polar align procedure find a solution.

If my FOV is too small, why, except that the plate solving may fail, would polar alignment fail to continue?

Regards,

Vince

[admin]

Hi Vince,

basically the field of view is too small for the plate solving engine that the polar alignment uses, which can only go down to about 0.5 degrees in each direction. Within the smaller FOV that you have, there are not enough stars that are matched up with stars in the polar align plate solving index for the calculation to succeed.

SharpCap 4.2 (will be in beta soon) is switching to polar alignment using the newer plate solving engine that SharpCap now has for all sky plate solving (in fact I have made that code change already). When that version is available, if you have the 'hi res' plate solve database installed then it ought to stand a very good chance of working at your 0.3x0.18 degree FOV. I could possibly also extend the polar alignment to allow the 'ultra hi res' index to be used, but that would come at the expense having to be closer to the pole (within about 3 or so degrees, rather than 6).

cheers,

Robin

[DrAstro]

Robin,

If you need a tester sooner, I'm available!

Vince