On several different occasion I was going to attempt imaging a dark nebula, aka galactic dust. Though these nebula are as you might expect, a dark coal color and are very hard to image in light polluted areas. Especially the red zone from which I capture most of my deep space images.
Two nights back I made the decision to go for one such nebula, NGC 7023 the Iris Nebula. The Iris nebula itself is a very small object to be imaging at less than 300mm, though the dark nebulous dust clouds that surrounds this object are rather large, in fact this entire constellation of Cepheus is loaded with them. These dusty clouds of cosmic soup are in reality debris fields that run throughout the arms of our Milky Way Galaxy and not actually part of the Iris Nebula.
With The Weather Underground and Ventusky both predicting two beautiful, clear nights back to back I made a decision to target NGC7023. Just to see if I could capture the slightest hint of the dark nebulosity I had wondered about so many times before.
With night falling I went into imaging mode and began going through a routine that I have become extremely proficient at.
My telescope mount stays put most of the time, so polar alignments are normally a matter of tweaking an already accurate alignment by an arc second or so. I then go through a star alignment process even though the mount that I am using stays fairly well aligned from one night to the next. This to is usually a matter of some minor tweaking. Once I’m sure my mount has an accurate idea of where it’s pointing I fire up the most fascinating and frustrating instrument used to aid in the imaging of deep space objects, my autoguiding system.
If you didn’t already know a goto telescope mount tracks the night sky, compensating for earths rotation. Unfortunately the mount that I am using has horrible periodic error which are inconsistencies in the worm gear which drives the mount. My autoguiding system consists of a 2nd separate camera and small telescope which are dedicated only to autoguiding. How it works is. The auto guiding camera finds an ideal star through the guide scope and locks onto it. Once locked onto a star the system analyzes it in a very precise manor. If the star moves even the slightest bit the system will send a command to the telescope mount. Telling it to compensate for that movement. Keeping the main imaging camera in a seemingly steady position.
With my astrophotography gear set up and calibrated I slewed my telescope toward the north eastern horizon and began imaging. The first night of imaging NGC7023 I captured 14, 120 second exposures.
To get a general idea of what I was collecting here I did a quick stack and stretch on that data. I can’t say that I was very thrilled with my results either. I saw absolutely no evidence of the coal black nebula I had been hoping to capture. The Iris Nebula was visible, but not much else.
Realizing I was only looking at about 30 minuets of exposure time I made a decision the following evening to collect more data of this area of the cosmos. That evening I was able to capture 40, 120 second exposures before having to shut things down.
So at this point I have right about 2 hours worth of exposure time on this object. With a quick stack, a stretch of the data and some post processing the dark nebula are beginning to show themselves as indicated in the photo posted above.
The sight of dark dusty nebula in my data has me feeling extremely optimistic toward my efforts. Of course this is just beginning, Ive literally just crossed the starting line on this one and am looking at some distance between the data that I’ve captured so far and what I expect to have in order for me to complete this photo. My goal is to collect 8 to 10 more hours of exposure time on this object before considering it complete.
Anyway I hope you enjoy what I captured so far.
Till next time, Eyes to the sky and cameras focused!