The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by William Herschel in 1792. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 to 400,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures.
The Crescent Nebula is a rather small object located about 2 degrees Southwest of Sadr. While considered bright by astronomical imaging standards, visually it is relatively faint. For most telescopes it requires a UHC or OIII filter to see. Under favorable circumstances a telescope as small as 8 cm (with filter) can see its nebulosity. Larger telescopes (20 cm or more) reveal the crescent or a Euro sign shape which makes some to call it the "Euro sign nebula".
Newton 200/1000
ASI 294 mc-s pro, gain 122, temp. -10
Zwo Eaf
Guide 60/240 with ASI 120 mc-s
ASI air plus
Coma corrector baader Mark iii
Optolong l-ultimate (20h*600") + l-quef (4h*300")
Eq6 pro kit rowan
Dark, flat, dark flat
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#CoelumAstronomia #Astronomia #Astrofotografia #Universo #Astronomy #Astrophotografy #Universe #Cosmologia #Cosmology
Data e Ora di acquisizione 18 Luglio 2024 alle 04:00 |
Condizioni del Cielo Clear sky, Bortle 9 |
Filtri Utilizzati Optolong l-qef, Optolong l-ultimate |
Diametro del Telescopio 200 mm (7") |
Focale di Acquisizone 1000 mm |
Soggetti Caldwell 27, Nebulosa Crescente - Crescent - NGC 6888, NGC 6888, Sharpless 105 |
Schema Ottico del Telescopio Riflettore Newton 200 F5 |
Marca del Telescopio Skywatcher |
Fenomeno o Evento Astronomico Emission nebula |
Tipo Immagine Digitale |
Dispositivo di Acquisizione CCD |
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