NGC 3242, nicknamed “The Ghost of Jupiter Nebula” due to its similarity with the giant planet in diameter (roughly 32-35 arcsec) and in appearance in a small telescope, is a planetary nebula that really puts a great show. It is an interesting object because, additional to the attractiveness of its central region as a planetary, showing a nice and delicate structure in concentric layers, it also has some bright filaments that glow in the light of Hydrogen II and also in OIII.
The exact origin of this surrounding nebulosity is not yet fully known. Some authors consider it to be part of the expelled gas layers from the original star (HD 90255, mag 12.1), while others consider that this gas belongs to the ISM (InterStellar Medium) that has been illuminated (and heated) by all this process. This image was taken with narrowband filters (and short RGB exposures to capture the surrounding stars’ natural colors), but with three different exposure times: 30 min per subframe to capture the surrounding nebulosity (but this completely wipes out all detail in the structure of the much brighter core), 5 min and 1 min to capture detail in the core. This HDR combination during the processing allows for an image with both planetary nebula and surrounding nebulosity. The inner colors have been combined with the 1 and 5 minute exposures only, while the rest of the image receives its color from the 30 min exposures. The inset below shows the detail of the inner nebula.
Name(s): NGC 3242. The Ghost of Jupiter Nebula, The CBS Eye
Type: Planetary Nebula
RA: 10h 24m 24s
Dec: -18º 50’ 13”
Size (arcsec): 40×35 arcsec
Distance: 1,500 ly
Date: 2019-01-17 to 2019-02-10
Location: iTelescope.net, SSO near Coonabarabran, NSW Australia
Size (arcmin): 35×31
Telescope: Planewave CDK 20” f/6.8
Camera: SBIG STX16803 (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 20.5 hours (Ha: 9h30m; OIII: 9h30m; RGB: 1h30m)
Processing: CCDStack, Photoshop CC 2019