I am trying to understand what's the relationship, if any, between the sharpness of the individual frames versus the sharpness of the final stacked RAW through WBPP.
My latest image https://www.astrobin.com/full/q1t9sq/0/ has an average FWHM of the individual frames, measured before stacking through subframe selector, of 1.85" (around 4px at 0.46 arcsec/pixel). After the stacking process, the resulting FWHM is around 4.6px, or 2.15 arcsec. I am trying to understand if i am losing sharpness during the stacking due to some internal process (maybe imperfect star alignment?) or this behavior is to be expected. To be noted that this discrepancy is somewhat more noticeable with my C11 (which was used to take that image) versus my RC (stacks coming from the RC data are usually much closer in FWHM to the average calculated using SFS).
Does anyone have insights on the topic?
My latest image https://www.astrobin.com/full/q1t9sq/0/ has an average FWHM of the individual frames, measured before stacking through subframe selector, of 1.85" (around 4px at 0.46 arcsec/pixel). After the stacking process, the resulting FWHM is around 4.6px, or 2.15 arcsec. I am trying to understand if i am losing sharpness during the stacking due to some internal process (maybe imperfect star alignment?) or this behavior is to be expected. To be noted that this discrepancy is somewhat more noticeable with my C11 (which was used to take that image) versus my RC (stacks coming from the RC data are usually much closer in FWHM to the average calculated using SFS).
Does anyone have insights on the topic?