Iiro's DeepSky Sketches

Name: PK 205+14.1 (Abell 21)Other name: Abell 21
RA: 7h 29m DEC: +13° 15'
Constellation: GEM
Type: Planetary nebula
Magnitude: 14.1
Size: 10' x 6'
Surface brightness: 16.4
Brightest star: 15.9
Description: 13"-F,pL,E at 100X with UHC, crescent shape
Notes: Medusa nebula,large and low surface brightness
Observer: Iiro Sairanen
Location: Härskiänsaari, Ruokolahti, Finland
Date: 8/9.3.2005 22:50
Instrument: Newton 406/1830 mm
Magnification: 57xFilter: O-III
Field: 50'Seeing: 3
Background sky: 3NE lim mag: 6.1
Visuality: IIIHeight: 35°
Weather: -11°C, strong wind, northern lights
Description: 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.
Updated: 1.4.2005 18:02