The Iris Nebula

Ever since I first observed it, I have felt the Iris Nebula is one of the most beautiful deep sky objects.  To me it looks like a bright beacon star shining through a blue-golden tunnel.  A couple of years ago, not long after I started posting images to Astrobin, my Iris Nebula image was selected as "image of the day."  I don't know how that happened; maybe it was the only image posted that day, but nevertheless that was a great encouragement to a relatively inexperienced astrophotographer using cheap equipment.  I've been a little reluctant to go back to this target because I thought I couldn't improve on it.  Now I think my skills are better so I decided to try it again.

It was quite gusty when this was imaged but also quite clear.  I had some difficulty focusing because the scope was blowing around so much. Seeing was relatively poor too.  So conditions for this image were not very good.  I used the PicGoto starting from alpha Ceph and easily found the Iris Nebula.  I ran the chiller at 2.5 A; starting temperature was 8.5 °C on the CCD.  It was a warm night, so I consider that level of cooling pretty good. I used the low pass Dec guiding algorithm instead of "resist switching," which is what I usually use.  I can't tell whether the algorithm really helped (because I think the wind was the biggest factor), but things did seem to settle down after I started using it (and went to bed).  Overall, I was happy with the number of subs I was able to keep and feel this is a much better image than my one and only "picture of the day" image from two years ago.  

Date: 3 Jun 2014

Subject: NGC 7023, Iris Nebula

Scope: AT8IN + HPS Coma Corrector

Filter: None

Mount: CG-5 (Synta motors, PicGoto Simplificado)

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.2.2 (Win 7 ASCOM)

Camera: DSI IIc chiller at 2.50 A, 8.5-3.5 °C

Acquisition: Nebulosity 3.2.0, no dither

Exposure: 46x300 s

Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3.5.279 Crop; Wipe:Color & brightness; Develop 87.49%; Color:Scientific, 250% sat.; HDR:Reveal core; Deconvolute auto mask 2.2 pix; Life:Heavy; Track RNC 17.40%. CS6 Astronomy Tools increase star color; Healing brush; Deep space noise reduction (twice); Levels; Astro Frame.

Just for comparison, and in the spirit of "look how far I've come," here's the image from two years ago.  I now think it is sharpened way too much, but at the time it represented a huge improvement over what I had been doing.  I used a focal reducer, so the field of view is wider than in the new image, in which I went the other direction by using a coma corrector.  One of the things I like about this older image is that it picked up the dark dusty "petals" that give the nebula its name; in my newer image, I'm framed tighter and you can't see them.

Date: 10 Jul 2012
Subject: NGC 7023, Iris Nebula
Scope: AT8IN + 0.5x Antares telereducer
Filter: none
Mount: CG-5 (Synta motors)
Guiding: Orion ST80 + 0.5x Antares telereducer + DSI Ic + PHD
Camera: DSI IIc
Acquisition: Nebulosity 3.0.8
Exposure: 60x180 s
Stacking: Neb 3, bias included, normalize first, auto quality screen, trans+rot align, 1.5 SD stackProcessing: Digital development with sharpening, power stretch, curves, star reduction in N3, separate layer with GREYCStoration, CS5 color blotch, deep space, & space noise reduction in the GREYCStoration layer, then layer mask with a Gaussian blur to preserve enhancement in the center and remove noise from periphery; saturation boost the flattened image.