This image shows the open cluster M46 in the constellation Puppis. The non-stellar ring of material that seems to be within the cluster is planetary nebula NGC 2438. The nebula is actually in front of the cluster, astronomers believe, and just a chance alignment makes the cluster and the nebula appear together in the sky.
A wide field view is great for an apparently large open cluster like M46. But to see the planetary nebula in detail, an imager must use a much longer focal length. How about this image, taken through narrowband filters with the 0.82 meter IAC80 telescope? The IAC80's 9-meter focal length reveals a host of details that my telescope's 0.5-meter focal length could never show.
As I was processing this image, I found another planetary nebula in it to the left of M46 and NGC 2438. This nebula is cataloged as Minkowski 1-18, PK 231+04.1, and PN G231.4+04.3. It is to the left (north) and down (east) just a bit from NGC 2438 and is near the edge of the frame. It appears as a dim, dark red, circular patch just a little larger than the footprint of the brighter stars near it. You may have to look at the full resolution image to see it. I was happy to see it as I did not know it was there before taking this image.
Telescope: SV80ED (and William Optics 0.8x II fr/ff (eff. at f/5.6))
Camera and Exposure: SXVF-H9C (46x480"), Alnitak Flat-man flats
Filter: Hutech IDAS-LPS2
Guiding: Meade DSI Pro and Hutech 50mm
Mount: Takahashi NJP
Software: Nebulosity, Maxim DL, Photoshop CS3
Location: The Woodlands, TX
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