The Enigma Nebula and a new PN Candidate Discovery Lu4

After taking a little astronomy break over the summer months, I am pleased to share an image of a currently unclassified object. I serendipitously came across this beautiful nebula late last year. I had taken some images of a different object and decided to do a test integration to see where I was at. When planning the image I had noticed some uncatalogued Ha emission at the very edge of the field of view and thought it would be interesting to see what this was.

After the integration to my surprise there was distinct OIII emission in the centre and on RGB images a distinct blue star was visible suggesting this may be a large uncatalogued planetary nebula. The candidate appears to have a faint outer shell to the East, and if this is confirmed, the major diameter would be 71.2 arc minutes, so it is a real giant and it may potentially be one of the largest known planetary nebulas! Unfortunately getting these new discoveries catalogued in the HASH database is now very difficult as a new object has to have a classic PN morphology. Pascal Le Dû and Professor Quentin Parker have reviewed my data but feel spectroscopic confirmation is required to confirm it as a new planetary nebula, and as such it has not been registered in the and HASH databases.  Of course it may also turn out to not be a planetary nebula but may be an ionised HII region.

Possible outer Ha shell and a possible central emitting star

After initially publishing my image, I received a number of messages about this object. It turns out Dana Patchick and Sakib Rasool looked at this object on survey data a few years ago but didn’t find a suitable central star. The StDr team of Marcel Drechsler and Xavier Strottner also examined it, and Bray Falls picked it up on a wide field image he took from his setup in Namibia, but like me, was unsuccessful in getting it registered in Tim Schaffer and the NHZ team also found the object on a wide field image they took. It is a pretty awesome reflection on the amateur community that we had 5 groups who all independently found the object on survey and Bray and Tim/NHZ with their own data, when it has been overlooked by the pros for so long! Dana Patchick suspects the CSPN I identified is likely a sub white dwarf (likely an sd, sdO, or He-sdO) and looks close enough to create such as shell. White sub-dwarfs do have a track record of creating giants shells, with the massive PaStDr 9 having a He-sdO as its emitting source.

In recognition of the amateur contribution to the object, we have all coordinated and the consensus was to refer to this object as the Enigma Nebula.

Smaller Planetary Nebula in the field of view including Ludgate 4

In addition to the Enigma Nebula, there is a second smaller new PN candidate to the bottom right of the image, which has been accepted as a new discovery in and HASH catalogued as Ludgate 4/Lu4.. There are also a number of known smaller and brighter PN, MPA J1413-6709, LoTr9 and WRAY 16-150  which appear superimposed on the much larger nebula.

Technical Details

Imaging Telescopes Or Lenses
Nikkor AF-S 400mm f/2.8E FL ED VR

Imaging Cameras

Chroma Filters

10Micron GM1000 HPS

Adobe Photoshop · Pleiades Astrophoto PixInsight · Starkeeper Voyager

Acquisition details

July 16, 2023 July 18, 2023 July 29, 2023 Aug. 10, 2023 Aug. 21, 2023


Integration:33h 15′


Dunedin, NZ

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