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)
LRGB = (9x6x6x10)*1200s
|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.