** Short Exposure Planetary Nebula series **
I figured this series could use another entry, so I spent some observation time on a neglected, small PN with a very interesting structure.
Unfortunately, wind was very strong during capture and I had to discard my 5 minute narrowband frames. I switched to 60 sec subs mid-sequence. All data was 2x drizzle stacked to increase visibility of small details. Mouse-over shows a magnified view of the individual channels.
The core of NGC 40 contains a bubble-shaped OIII structure, as seen on many entries in the Abell PN catalog. However, H-alpha data shows many irregular knots and ejections around the central star.
Data from
the 2.5 m Isaac Newton Telescope reveals the presence of concentric rings around the main barrel structure, similar to the rings around the
Cat's eye nebula (NGC 6543), but these structures are too faint for my short integration.
A hint of the supernova remnant CTA 1 can be seen in my H-alpha data, right above NGC 40. This structure is unrelated to the planetary nebula. I'd like to refer to the excellent image from Mark Stiles, in order to fully grasp the incredible differences between NGC 40 and CTA1.
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