Jacoby 1

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Below: The 10 hour OIII exposure.
Note the thin shock front at the upper right just outside the main ring

Object: Jacoby 1 (15:21:47, +52:22:06)
Date: 15.-17.07.2007 and 08.-15.08.2007
Scope, mount, camera: 12.5" Newtonian, f/5.1, MAM50, ST-10XME
Filter, exposure time: L, R, G, B, Ha, OIII (narrow band filters: Astronomik)

L,R,G,B and OIII were combined into a deep sum image (Lchi)
OIII was also added to G and to B for the colour channel
Halpha was added to R for the colour channel

LRGB = (9x6x6x10)*1200s
Halpha = 4*1800s
OIII = 20*1800s
Total exposure time: 22h20min
Location: La Palma, Roque de los muchachos
Comments: Image seeing: 1.9"
Data reduction with THELI, colour composition in PS.

Jacoby 1 is an ancient PN and was discovered only in 1995 by Jacoby & van de Steene. Its central star, PG1520+525, is extremely hot with a surface temperature of about 140000K (the bright blueish star in the centre of the nebula). Since then, Jacoby 1 has been imaged only once more by Tweedy & Kwitter (1996). At a distance of about 800pc (the helix nebula is about 150 pc), Jacoby 1 is one of the intrinsically largest PNs ever discovered. The image shown above is by far the deepest exposure of this enigmatic object, and probably the only colour picture so far.