Basic object information

Object name: PK 205+14.1 (Abell 21)
Popular name: Medusa Nebula
Object type: Planetary nebula
Magnitude: 14.1
Size: 10.0'x6.0'
Magnitude of central star: 15.9
Description: 13''-F,pL,E at 100X with UHC; crescent shape
Notes: Medusa nebula;large and low surface brightness

Catalog information

RA (J2000.0): 07h 29m 00.0s
Dec (J2000.0): +13 15' 00"

Constellation: Gemini


Observer: Iiro Sairanen
Obs. place: Härskiänsaari, Ruokolahti, Finland
Date/Time: 8/9.3.2005 22:50

Telescope: Newton 406/1830 mm

Magn: 57x

Filter: O-III

Field: 50'

NE Lim.mag: 6.1

Background sky: 3

Seeing: 3

Height: 35
Visuality: III
Weather: -11C, strong wind, northern lights

Very large planetary nebula which has a very low surface brightness. It needs a low power and a nebula filter. O-III is much better than UHC. The crescent-shape is obvious with averted vision. The brightest portions are on the both heads. The southern one is little brighter than northern, but northern one is much larger. There is also a star involved on the north edge.