This is the Monkey Head Nebula, NGC 2174, found in the northern section of the constellation of Orion. Exposure: 17 frames of 120 seconds for a total integration time of 34 minutes, all at ISO 1600. Captured in Nebulosity, cleaned up with PhotoShop, and finished in Aperture.
Image Info: Canon 60D at the prime focus of the KPO 18″ Reflector. Astronomic CLS in-camera filter.
Click on the image for a larger version.