NGC 6888 (Crescent Nebula)



NGC 6888 (Crescent Nebula)

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



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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
, , ,
Schema Ottico del Telescopio
Riflettore Newton 200 F5
Marca del Telescopio
Skywatcher
Fenomeno o Evento Astronomico
Tipo Immagine
Dispositivo di Acquisizione

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