RBA Premium Astrophotography

December 8th, 2011

Simeis 147 and surroundings

Posted: December 8th, 2011



Simeis 147, a supernova remnant also known as Sharpless 2-240, is an object typically photographed with narrowband filters, because under visible light it just appears too "poor" in comparison, mainly due to the fact that this object is extremely faint when imaged through RGB filters - and not too bright when using narrowband filters either! Narrowband data however deprives us from viewing the many other things happening around it.

Most narrowband+broadband compositions I've seen (usually H-Alpha + RGB or H-Alpha + LRGB) haven't been able to "fix" that, so I decided to give it a try, also expanding the typical already-wide FOV, to hopefully capture and visually document more of what's around.

The image being presented above includes the entire field I photographed, in a 3x1 mosaic, but down here you can see a composition that focuses on the supernova remnant itself:

Successfully combining narrowband data (H-Alpha in this case) and (L)RGB data can be tricky. One of the usual results is that, since H-Alpha data tends to produce very small stars, when combined with broadband data, the resulting image often presents a rather severe ringing around the stars. Also, some conventional techniques rely on mixing H-Alpha with the red (R) and blue (B) data, but in this case, my RGB data was rather poor so I couldn't rely on just this technique. Therefore, for this particular image I followed a number of conventional as well as non-conventional methods that proved to be rather successful in producing an image that visually documents this area of the sky. Also, as usual in many of my recent images, a multi-scale approach dominated post-processing, in particular to bring out the fainter details that hide behind the swarm of stars.

My daughter says this supernova remnant looks like a Christmas tree ornament, although I kind of see a piggy's head instead! :-)