Photographing the Iris Nebula

Located over 1300 light-years away in the constellation Cepheus lies the Iris Nebula. Unlike the more common emission nebula, whose ionized gases emit light on their own, the Iris Nebula is a reflection nebula. The wispy clouds seen here are tiny particles of dust and gas with light from the central star reflecting and scattering off them. A blue glow in the center forms from Rayleigh scattering - the same process that makes our sky look blue.

Reflection nebula, like the Iris Nebula, require many hours of imaging due to how faint they are. This image took over twenty hours of imaging time during June. Since there are only five hours of darkness each night, gathering this exposure time took me roughly two weeks. Note that this image is only 15% of the resolution of the actual image for uploading purposes.

In total, this image is composed of 22 hours and 29 minutes of data:

• 393 sub-exposures with the luminance filter accounting for 14 hours and 2 minutes
  • 287 @ 120 seconds
  • 87 @ 140 seconds
  • 9 @ 300 seconds (longer exposures capture fainter details but overexpose bright stars)
• 62 sub-exposures @ 180 seconds with a blue filter accounting for 3 hours and 6 minutes
• 52 sub-exposures @ 180 seconds with a green filter accounting for 2 hours and 36 minutes
• 55 sub-exposures @ 180 seconds with a red filter accounting for 2 hours and 45 minutes

Is this a "real" image?

Yes, but we wouldn't be able to see this with our own eyes as they are not "good enough." This image did require some post-processing: removing noise and light pollution, changing brightness and contrast to make it easier to view, and photometrically calibrating the colors to be scientifically accurate. I've done little other processing beyond this, as a realistic aesthetic for these objects is more pleasing than an artistic one.

Want to see more images of the Iris Nebula taken by other amateur astrophotographers? If so, head to Astrobin for hundreds of renditions of this celestial object.