M1 the crab nebula

M1 in SHO

The Crab Nebula (aka M1 and NGC 1952) is a supernova remnant and pulsar wind nebula in Taurus. The progenitor was a naked eye supernova recorded by Chinese astronomers in 1054. At the center of the nebula lies the Crab Pulsar, a neutron star about 30 km of diameter with a spin of 30.2 rotations per second, emitting pulses on a very wide range of the electromagnetic spectrum (from gamma rays to radio waves). At X-ray and gamma ray energies, the Crab Nebula is one of the brightest persistent gamma-ray source in the sky.

M1 in RGB

As far as acquisition is concerned, this is a target I always wanted to cover, but never did, mostly because the small size (420″ × 290″) requires a relatively long focal, or more precisely, a high image scale. With Moana, those restrictions were lifted, although 7 arc minutes remains on the small side for that astrograph’s field (the field is currently 45’x35′, soon to be extended with a new sensor).

Acquisition started at the end of 2022 around Christmas and finished during the following new moon in January 2023. I ended up trashing a lot of frames due to various problems: weather, seeing, high winds messing with tracking (definitely a drawback those big Newtonians), some focus instability with the new Hocus Focus version (maybe?) and the primary mirror possibly starting “flopping” in its cell, which will require a road trip, fix and recollimation as soon as I get the new camera to install.

So I acquired almost 30 hours, but decided to keep only the top of the crop (the target requires high resolution after all), and assembled a high quality 20 hours dataset of both color and narrow band, to allow creative combination of those 6 channels. I show above a minimalist processing of color and another one of SHO mimicking natural colors, to give an idea of the dataset’s potential.

Here is this dataset being pushed to the limits on Astrobin.

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