M1 comparison using data from 2MASS - Graham Relf
Graham writes:
I have been pursuing David Boyd’s point in his 2010 Presidential Address (in the current Journal) that we amateurs could usefully work on the huge amount of data that is available on the Internet which the professionals do not have time to analyse.
The 2-micron all-sky survey (2MASS) was a professional project that ran from 1997 to 2001. Its images are available as FITS files on the Internet for anyone to download and process (go to http://irsa.ipac.caltech.edu/applications/Gator/). 2MASS imaged in 3 wavebands: Johnson H, J and K (respectively centred on 1.25, 1.65 and 2.17 microns) using two 1.3 metre telescopes in USA and Chile.
I have used 3 such images of M1, the Crab Nebula, to make a false colour image, treating the H band as red, J as green and K as blue. That is what you see in the left half of this image. (Original files aH_asky_971018n0810185.fits, etc, created on 1997 Oct 18 at 9:14 UT). Compare this with optical photos and you will see that the shape of the nebula is rather different at these infra-red wavelengths.
As created, my RGB image had 64 bits per colour channel and I processed it as such to make the version on the right. I did a wide radius unsharp mask by blurring the image and then subtracting a proportion of that blurred version from the original. That had the effect of exaggerating subtle details. It is known that M1 has strong magnetic fields (partly from photography through polarising filters at optical wavelengths) and so I suppose my result probably shows gas looping around the field lines. Maybe no-one has seen this particular view before.
M1 has been in the news recently because the Fermi Gamma-ray Space Telescope has detected gamma ray flares from it, which no-one can explain.
Who knows what awaits discovery in the vast online repository of unanalysed images?
Graham Relf
www.grelf.net
@britastro