The Veil Nebula

ASI2600MM, 360mm f/2.8, 11..4h (RGB 3x20m, H-Alpha 3.2h, S 2.9h, O 4.3h)

The Veil Nebula is the visible light of a large supernova happened about 10000-20000 years ago. It is bright enough so it could be discovered in 18th century by William Herschel and first photographs were taken in late 19th century.

Even if this is a comparably bright and contrasty target, the finer structures require a decent amount of exposure time to reveal their details. This is my third image taken from this region and this sequence demonstrates the influence of aperture, exposuretime and use of narrowband filters:

The first image was taken with my f/5.8 APO and exposed for 3.8 hours using the one shot color camera. The image in the center is a rather short test image taken during my first light session with the fast f/2.8 Newton, also with the OSC. Comparing the times according to the aperture, the first image receives slightly more photons, 37 minutes at f/2.8 translates to roughly 3.0 hours at f/5.8. As a result both images show similar details (even if the APO image was scaled down) and the faint structures still stay in darkness.

The right image is a crop from the new version and captured photons over 11 hours at f/2.8. Now the fainter structures in O3 spectrum get well defined.

This can be observed in other parts of the image as well.

Now we can even see the very faint edge in H-Alpha spectrum around the eastern Veil Nebula (NGC6992).

And the details of the western Veil Nebula (NGC6960) get pretty defined, even without complicated sharpening. The whole image only received a minimum of sharpening.