Wednesday, 30 September 2009

The Crescent Nebula

This object is a splatter of red and blue paint flung out from a seething star. Here, the hot star's shed atmosphere is lit up by it's ultraviolet light and fluoresces in hydrogen light. The star is the 7.4 magnitude Wolf-Rayet star, PPM 84423 in the constellation of Cygnus. Just before I slotted the camera into the scope I got a stunning view of this strange arc. I used a 20mm wide-field eyepiece with a Lumicon Ultra High Contrast filter on the 20" telescope (f=2400mm). However, I didn't see the lovely colours shown here. The picture is 9 stacked 30 second exposures, plus flats and darks and the object is called NGC 6888, or the Crescent Nebula. I managed to dismantle my field flattener and insert the lenses into my camera adaptor to convert the f/4.8 scope into an f/3 scope a.k.a a 'light bucket'! The nebula can be found by aiming 1/3 of the way between the bright stars Sadr and Eta Cygni, and moving a tiny bit right. Look for the little W or M - the bright stars you can see in the lower portion of this picture.

Deeper still

Here's the latest 82 images of Gyulbudaghian's Variable nebula stacked with a more carefully taken flat field. Just thought I'd share it with you. Look around the red star PV Cephei in the dark 'hollow' at the centre - can you see a jet shooting out below and slightly to the right? This is the nebula I'm looking for - not the vast billowing clouds swallowing up the stars at the left. It's madly overexposed as I couldn't resist turning up the contrast!