Simeis 147

(Sharpless 2-140)

Simeis 147 (a.k.a. Sharpless 2-140) is the remant of a very old supernova straddling the border of Taurus and Auriga. The shell of expanding gas has expanded to huge proportions -- over 3.5 degrees wide, or more than 7 full moons wide. Due to its huge size and age, it is also extremely faint and challenging to image. This is a mosaic of two frames showing the southern portion of it.

This is also one of the first images captured using my new STL Remote Guide Head. One surprising feature of the remote guide head is that, by turning of the internal guider, a lot of dark current was reduced, and the amp glow from the guide camera was completely eliminated. This is good, but on the down side, my existing dark frames were now useless. Thus, no darks were applied to this image. Instead, I simply relied on the guider dithering and sigma-reject combine to eliminate the hot pixels.

Takahashi Sky 90 at f/4.5
SBIG STL-4020M + Remote
Takahashi EM-200
Hutech LPS filter
H-Alpha: 5 hours (20 minute exposures)
Processed with Maxim/DL, CCDStack, and Photoshop CS4
Noel Carboni's Astronomy Tools