Polarisation structure of the Crab nebula (M1)
AAO image reference 'Crab polarisation'.    « Previous || Next »

Crab nebula polarisation structure
Top left is NE. Image width is about 9 arc min
Image and text © 1990-2002, Malin/Pasachoff/Caltech, Photograph from Hale 5m plates by David Malin.

The image was made from four plates taken on the Palomar (Hale) 5m telescope in November 1967, using a filter that excluded the emission lines, allowing only the highly polarised synchrotron light through. Each of the four images was taken with a Polaroid filter rotated 45 degrees (ie 0 deg, 45, 90, 135, 180). One of these plates was contact copied to make a positive film copy, and this positive aligned in turn with each of the three remaining images, revealing the difference between them. These three difference images were captured on film and used as the red, green and blue channels to make a colour negative which made the print. All the work was done photographically, but the image has subsequently been digitally remastered from the photographic derivatives. These are 'false colours' which is not meant to imply something underhand, rather colours used to make visible something that could not be seen through a telescope, even with Polaroid. They thus represent the invisible, inflated magnetic field of a star that exploded almost 1000 years ago.

Entry from NGC 2000.0 (R.W. Sinnott, Ed.) © Sky Publishing Corporation, 1988:
NGC 1952  Nb 05 34.5  +22 01 s  Tau  68.4  vB, vL, E 135deg +/- , vglbM, r; = M1
Related images
Crab nebula. The Crab nebula, M1 the Crab nebula.
Crab_wf.       The Crab nebula, wide field view

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