The Crab Nebula ( M1) is a supernova remnant and pulsar wind nebula in the constellation of Taurus. The nebula was observed by John Bevis in 1731; it corresponds to a bright supernova recorded by Arab, Chinese and Japanese astronomers in 1054. At X-ray and gamma-ray energies, the Crab is generally the strongest persistent source in the sky. Located at a distance of about 6,500 light-years from Earth, the nebula has a diameter of 11 light years and expands at a rate of about 1,500 kilometers per second. It is part of the Perseus Arm of the Milky Way Galaxy.

At the center of the nebula lies the Crab Pulsar, a neutron star, 28–30 km across, which emits gamma rays to radio wave pulses with a spin rate of 30.2 times per second. The nebula was the first astronomical object identified with a historical supernova explosion.

The nebula acts as a source of radiation for studying celestial bodies that occult it. In the 1950s and 1960s, the Sun's corona was mapped from the Crab's radio waves passing through it, and in 2003, the atmosphere of Saturn's moon Titan was measured as it blocked out X-rays from the nebula. The creation of the Crab Nebula corresponds to the bright SN 1054 supernova that was independently recorded by Indian, Arabic, Chinese and Japanese astronomers in 1054 AD. In the early 20th century, the analysis of early photographs of the nebula taken several years apart revealed that it was expanding. Tracing the expansion back revealed that the nebula must have become visible on Earth about 900 years ago. Source Wikipedia.



The image was captured with the Meade 12"LX200, using the Atik 383L+ mono at F6.11. I used Astronomik's 12nm Halpha, OIII and SII narrow band filters. All subs were taken at 1x1 bin, -10C, and 10 minutes each.

Ha : 35 subs (5.83 hr) on Mar 14th and 15th.

O3 : 32 subs (5.33 hr) on Mar 17th and 21st.

S2 : 30 subs (5.00 hr) on Mar 24th and 26th.

Processing was done with PixInsight, following (for the most part) kayronjm's tutorial of Feb. 24th. Both Ha and O3 were combined to develop the Luminance image. Original color mix is per Juan's preference. Final color mix is my own concoction. See below formulae. Click on the small images in the upper right to see the differences.

ORIGINAL:

R = .5S2 + .5Ha

G = .15Ha + .85O3

B = O3

FINAL:

R = .5O3 + .5Ha

G = .15O3 + .85S2

B = S2

North is up. This is a sizable crop. Images continue to be plagued by garish vignetting, and the only solution so far has been to crop the feature out (notice upper left corner).