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SHARPLESS 2-294 (AKA THE OCTOPUS NEBULA)

EMISSION NEBULA IN MONOCEROS (THE UNICORN)

(Image centered at: ra 07 h: 16 m / dec -09º 25')

CLICK THE IMAGE FOR A HIGH RESOLUTION VIEW

January - 2025, Home Backyard in Martinez, Buenos Aires, Argentina

DATA

TYPE: Emission Nebula

APPARENT DIAMETER: 3.4 arc seconds in diameter

APPARENT MAGNITUDE (V): NA

DISTANCE: 3.2 k to 4.8k parcecs (or 10.000 to 15.000 light years)

IMAGE INFORMATION

INSTRUMENT: 6" ORION OPTICS UK (Ultra Grade Optics) w/Sky Watcher Coma Corrector (0.9x) working at at f4.5

CAMERA: QHY 183 MONO

MOUNT: VIXEN GDPX, OAG with Starlight Xpress Lodestar

FILTERS: BAADER LRGB Set + ANTLIA HA 4nm

SKY CONDITIONS: urban skies - Bortle 8

EXPOSURES: HaRGB (120,60,60,60)

OBJECT DESCRIPTION AND IMAGE SESSION

Sharpless 2-294 is a a HII region ionized by a single B0.5 V star (a main sequence star burning hydrogen). The nebula features several infrared excess sources, a photo dissociation region, and also a group of reddened stars at its border. 36 young stellar object have been identified with an estimated age of ∼4.5 × 106 years. The distance to Sh 2-294 is uncertain and varies from 3.2 kpc to 4.8 kpc.

It is located at 1 degree north from the open cluster NGC 2353 and 3 degress from the Seagull Nebula Complex

This nebula was discovered in 1950 by German astronomer Wolfgang Strohmeier during a photographic survey of the winter Milky Way. He used a Schneider Xenone 1:2 lenses with 125 mm focal length. Of 42 nebulae this one was listed as number 8 (Strohmeier 8) with a size of 4x6 arcminutes.  In 1959 the American astronomer Stewart Sharpless published his catalogue of 313 H-II regions discovered on the 48-inch Schmidt telescope photo plates of the «Palomar Observatory Sky Survey». The nebula is listed there as number 294 (S 294, Sh 2-294, Sharpless 2-294) with the description: Bright nebula of irregular form and amorphous structure with a diameter of 7 arcminutes. Because the nebula looks a bit like an upside-down octopus with is arms curled in, it got the nickname «Octopus Nebula».