Early this morning I observed the planetary nebula NGC7094 in the constellation of Pegasus. A faint, round glow in my 12" SCT. Nothing spectacular.
What was worth noting, is the nebula's central star. Most if not all stars react to UHC, and especially OIII filters by dimming visually. Stellar PN's can often be teased out by "blinking"; alternating between a filtered and unfiltered view, to see which "star" remains visible, thereby revealing itself as the nebula.
The central star of NGC7094 appears to be an exception. It remained easily visible when filtered, either by an OIII or a UHC filter. I suspect this may be due to a shell of nebulosity surrounding the actual central star. If so, such a shell may be the cause of the central star remaining easily visible when filtered.
Anyone else noticed this effect?
This link has some scientific info on NGC7094's central star.
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