The Iris Nebula, also NGC 7023 and Caldwell 4, is a bright reflection nebula and Caldwell object in the constellation Cepheus. NGC 7023 is actually the cluster within the nebula, LBN 487, and the nebula is lit by a magnitude +7 star, SAO 19158. It shines at magnitude +6.8. It is located near the Mira-type variable star T Cephei, and near the bright magnitude +3.23 variable star Beta Cephei (Alphirk). It lies 1,300 light-years away and is six light-years across. [Source: Wikipedia]

The image was captured with the Celestron CGE Pro mount and the venerable Meade 12"LX200 SCT, using my Atik 383L+ mono at F7.16 (i.e. 2182mm FL). Astronomik's Luminance, Red, Green and Blue filters were used. Imaging subs were taken at 1x1 bin, -10C, and 10 minutes each for all subs.

Image information -- 2017

Image --

Lum 600s: 59 subs (9.83 hr) on Aug 16th, Aug 18th, and Aug 20th.

Red 600s: 14 subs (2.33 hr) on Aug 21st.

Green 600s: 18 subs (3.00 hr) on Aug 21st.

Blue 600s: 30 subs (5.00 hr) on Aug 20th.

Processing was done with PixInsight, following (for the most part) kayronjm's tutorial of Feb. 24th. Only L was used to develop the Luminance image. R, G and B were collected for the color mix. Narrow band filters were not used on this project.

North is to the right (I think), and this is a slight crop due to the misalignment accumulation from so many different filters and times. I am fairly pleased with the outcome.

I originally imaged this target in September 2015. Unfortunately, the Atik 383 camera showed an almost regular pattern of very small contaminants across the entire image. At that time, I was not able to remove these spots (stipples) with flats, so I abandoned the project. I then sent the camera to Atik in the U.K. and had the sensor cleaned.

The irony is as I was working on the current version of this target, I once again saw the stippling on the image. Fortunately, the Flats are sufficient to remove this effect for the time being. But now I've got to decide whether to send the camera back to Atik (again), or attempt to clean the sensor myself. We will see .....

This would have been a good use of PI's HDR Composition tool for combining long and short exposures. However, with the stippling problem re-surfacing, I was not able to do any 60s exposures.