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NGC 2440
Planetary Nebula
aka PN G234.8+02.4, PK 234-2.1, ARO 47, ESO 560-9
RA: 07h41m55.4s, Dec: -18°12'31" (2000) in Puppis
Magnitude: 11.5
Size: 1'
Mean Surface Br. 19.9 Mag/arcsecē

Minimum requirements to detect: 6-inch telescope

I think the planetary nebula NGC 2440 (NGC 2440, PNG 234.8+02.4, PK 234+02.1, ARO 47, ESO 560-9) is one of the finest in the sky. Catalogs list it as a 10.8 magnitude object a mere 16" in diameter.  Like many planetary nebulae, in small telescopes or at low magnification it appears as a small, elongated blob. Hunting it down and finding it in such instruments is a reward in itself. In larger instruments some of the detail in the above image begins to appear, making this a fine visual object.

This image from the DSS shows a 20' x 20' field around NGC 2440. North is down and east is to the right.
 

I first observed NGC 2440 in my 18-inch in January 2000. I was a bit surprised by how bright it appeared. It is brighter than the 11th magnitude listed. The planetary was obviously non stellar at 100x and appeared as a tiny smudge. The best view came at 425x, where it appeared distinctly bipolar, as seen in my sketch on the left. At the heart of the nebula is two bright knots that nearly touch. The surrounding nebulosity stretches in the directions perpendicular to a line between the knots, and is brighter and extends farther to one side. This one's definitely going on my list favorites due to its interesting structure.

 

This is the view of the field in a 6-inch at 50x.  North is up, east is to the right.

This image was obtained with the Hubble Space Telescope. Don't expect it to look anything like this in the telescope! At the center lies a newly formed, 17.5 magnitude white dwarf star--the now bare core of the original star after puffing its outer layers away to create the nebula.

Millennium Star Atlas Vol I Chart 319
Sky Atlas 2000 Chart 12
Uranometria 2000 Vol II Chart 319
Uranometria 2nd Ed. Chart 153
Herald-Bobroff Astroatlas B-12 C-69