For this M1, light was collected at two telescopes. On the one hand by Marco Eckstein on the Edge HD8 and by me on the refractor 160/1600.

Marco:

Celestron EgdeHD 8 - ASI2600MC Pro - Optolong L-eXtreme

23.-25.02.2021

65 x 8 min = 8 h 40 min

Lars:

Refraktor AOM 160/1600 + Riccardi 0,75 - ASI1600mmc

22.02.-08.03.2021

(20 x 5 min + 28 x 10 min =) 380 min H-alpha (astrodon 5nm)

(24 x 5 min + 33 x 10 min =) 450 min [OIII] (astrodon 5nm)

total: 22,5 h

Each first stacked their own data and Marco took over the further processing. The calibrated H-alpha and OIII stacks of both telescopes were registered and stretched on top of each other via the Astro Pixel Processor.

Further processing took place in Adobe Photoshop after the stars were removed via StarNet ++. Since the StarNet ++ tool does not work properly (some filaments in the nebula were incorrectly identified as stars!), All structures in M1 were first checked and, where necessary, restored using a layer mask. Thanks to the long exposure time, the noise was low, which made further processing much easier. The increase in contrast and the emphasis on structures and colors could easily be carried out with the CameraRAW tool in Photoshop. The SmartSharpen filter in Photoshop, among other things, was used to sharpen it, which delivers results similar to deconvolution, but offers very fine setting options and a quick preview.

In the last step the stars were added again.

Often good seeing and the exposure time of 22.5 hours, the filaments in the fog could be worked out very filigree. This allows a lot to be discovered in the Crab Nebula.

A faint structure running from the center to the north outside the bright nebula, which we had not seen so clearly in this form before. If it were created together with the supernova explosion, this "tube" would have to travel significantly faster than the bright rest of the nebula.

The picture was presented on the german side astronomie.de as Astrofoto der Woche (Astrophotography of the week.

Peter Riepe wrote about the "tube":

"It shows an intertwined structure with parallel sides that extends (you can measure it in the picture) about 165 '' to the north. Sidney van den Bergh discovered this extraordinary detail as early as 1970 (Astrophys. Journal 160, L27). However, they only stated 90 '' x 45 '' dimensions. Twenty years later, a spectroscopic study by M. Marcelin et al. with the telling title: "Kinematics of the Jet of the Crab Nebula" in Astron. & Astrophys. 228: 471-476 (1990). This investigation showed that this jet has an expanding cylinder shape, which expands along its axis at an average speed of 260 km / s. This results in a measurable extension of 0.22 '' per year (Fesen & Gull, 1986)."