SH2-240 (Simeis 147)
A supernova remnant

Simeis 147 is a supernova remnant with an apparent age of about 100,000 years. It covers nearly 3 degrees on the sky toward the direction of Taurus constellation with a typical filamentary structure. This very faint object was discovered in 1952 at the Crimean Astrophysical Observatory by using a 25-inch Schmidt camera. Because the  extremely low superficial brightness, the objet is hard to photograph...

Optic: Canon 400 mm f:5.6 L. Camera: Modified Baader Canon 350D (Ha pass filter - see here) at ISO800. Processing: Iris software. Exposure:  45 minutes (9 x 5 minutes). Location: Pic du Midi (altitude 2860 meters, french Pyrénées). Date: August 31.15, 2006.

Simeis 147 is only weakly visible in a standard color image

The nebula is more visible by using only the red layer (negative view)

Here a high contrast version of the black & white image (red channel)

Display a larger version - (1730 x 1150 pixels)