I set out to image IC 63 "the Ghost of Cassiopeia" and happened across ghosting of a different type. Come to find out I was getting some diffraction spikes from Navi. After posting the question on Cloudy Nights it looks as though CCD chips can reflect light from the sensor, onto the filter, and cause ghost reflections. The light from a bright star (in this case a magnitude 2.15 star) is reflected internally by the narrowband filter and entered the CCD chip again causing the spider pattern seen in the image. The pixel cells on the CCD surface is acting as a diffraction grating which is the reason for the even spacing of the spider vane shadows. Many pixel cells, on the chip, are causing the many spider vanes to appear.
Lesson....avoid imaging targets with bright stars in the field using this gear.
Imaging scope AstroTech 8 inch Ritchey-Chretien
AstroTech Field Flattner
Astrodon 5nm Ha filter
QSI 683wsg-8
20 min subs
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