Helix Nebula (NGC 7293)

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About this Image

The Helix Nebula is one of the apparently largest planetaries known: Its apparent size covers an area of 16 arc minutes diameter, more than half of that of the full moon; its faint halo extends even further to 28 arc minutes.

This is the closest of all planetary nebulae lying at a distance of perhaps 450 light years. A planetary nebula is created at the end of the life of a Sun-like star by expelling its outer gas shell into space.

High resolution images are showing lots of tiny cometary knots with the tail pointing away from the center of the nebula.
North is up. The above image is a LRGB version.

Below you see the Nebula including the faint outer halo (2 hours of H-alpha incorporated).
The image benefits from the extremely dark sky at Hakos and the high position near zenit.

clic for 100% size 1396 x 1348 (277 kB)


Technical Details
Optics

105mm TMB refractor with flattener at f/6.5

Mount AP-400 GEM
Camera SBIG STL-11000M at -20C, internal filter wheel
Filters Astronomik H-alpha (15 nm) + LRGB
Date Aug 13, 2004.
Location Hakos/Namibia
Sky Conditions mag 6.5, high transparency, good seeing, temperature 10-15 C,
Exposure Ha = 120 minutes,
LRGB= 20:20:20:20 min (all 10-minute sub-exposures)
all 1x1.
Processing Image aquisition in Maxim DL 4.0; Image calibration, aligning, mean stacking, DDP and color synthesis in ImagesPlus;
Photoshop: H-alpha blended to red and L channel; cropped; size 50/100 %;