SharpCap Forums

Hello colleagues,
I have used this feature already with several telescopes and mounts and always I was able to get very precise results.
One week ago, I tried this with my Toscana-Remote-Observatory; G2-1600 CCD by Moravian Instruments, FOV 45x30 arcmin; 35 stars availabe 15 stars usable. But SharpCap showed my "plate solve not possible" (or similar). I tried then to do it with PHD2 - with no success - returned to SharpCap and suddently it worked normal. I got it to "fair" and wanted to improve it. SharpCap frooze and after restart it showed again plate solve not possible, although there were enough stars availabe and marked.
Does anybody know WHY it does not work correctly anymore?
Thanks for help, rfa

Hi,

45x30 arcmin FOV is about as small as you want to go - at that scale there are possibly areas where you may not get a solve because of a lack of bright stars in the field of view (SharpCap's database goes down to Mag. 13 - you could just end up looking at a field where there are only a few stars brighter than mag 13 by simple chance). Another possibility is that you are on the edge of the area of SharpCap's polar star database (dec=83N), although this seems less likely.

Usually a good trick to check this sort of situation is to save a single frame to PNG or FITS via the snapshot button and then try to plate solve it with nova.astrometry.net - you can check both what co-ordinates you are pointing at and also the brighter stars in the frame.

cheers,

Robin

Hi, thank you for your prompt reply.
The strange is, that I did it already several times with this FOV, sometimes with even worth sky conditions (small cloudiness etc.). This time the sky was very good. I standardly use plate solving of other software - it works within seconds. In the manual is written, SharpCap need minimum 10-15 stars for plate solving: I have had all times 15 "usable" and more, total 30-50, depending on the threshold.
If SharpCap is week in platesolving, why not combining it with a stronger platesolver?
How far from the celestrian pole does SharpCap work? Can I change the position still using the 90 degrees angle?
rfa

Hi,

the plate solving built into the polar alignment is designed to be very fast to provide immediate feedback. It has a database out to 7 degrees from the pole.

There is no need to start in the exact 'home' position, or to rotate through exactly 90 degrees - you can start in any RA position and rotate by any reasonable amount (more than 45 degrees recommended).

If you still have problems, please do save a single frame and share it and I will investigate if there is any problem with the plate solving, or if anything can be improved.

cheers,

Robin