I am imaging with a 10inch f4 Newtonian with a coma corrector. The coma corrector will (probably) introduce distortion into the image. I am observing an issue with Astap plate solve where i.e. deepsky object annotation matches very well in the center of the image but deviates towards the edge. Is there a way to introduce polynomial mapping to the solve to have good mapping across? Attached are screen grabs from left/right edge region of the frame as well as center. Notice that the markers for deepsky objects are fitting perfectly at center but are offset towards the edges.
Yes there is. The best polynomial fit can be provided by nova.astrometry.net. When you upload an image to nova.astrometry.net you can change under advanced, option tweak the polynomial to 3 or higher. ASTAP can read this polynomial factors and use it when annotating.
It is also possible in ASTAP. It uses a more primitive calculation. Under tools there is an option "Add SIPP coefficients to the header". This adding SIP coefficients is as an option also available in the Batch convert menu .
Han
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Hi,
I am imaging with a 10inch f4 Newtonian with a coma corrector. The coma corrector will (probably) introduce distortion into the image. I am observing an issue with Astap plate solve where i.e. deepsky object annotation matches very well in the center of the image but deviates towards the edge. Is there a way to introduce polynomial mapping to the solve to have good mapping across? Attached are screen grabs from left/right edge region of the frame as well as center. Notice that the markers for deepsky objects are fitting perfectly at center but are offset towards the edges.
Using version 2023.04.19
Cheers,
Gert
Last edit: Gert 2023-04-21
Yes there is. The best polynomial fit can be provided by nova.astrometry.net. When you upload an image to nova.astrometry.net you can change under advanced, option tweak the polynomial to 3 or higher. ASTAP can read this polynomial factors and use it when annotating.
It is also possible in ASTAP. It uses a more primitive calculation. Under tools there is an option "Add SIPP coefficients to the header". This adding SIP coefficients is as an option also available in the Batch convert menu .
Han
Hi,
OK, found it. Much better fit of the deepsky annotation now! Perfect.
Thanks for the great work!
Cheers,
Gert