Iris Nebula

[alan4908]

My first attempt at capturing and processing the Iris Nebula. I went for an LRGB approach and the image representing about 11 hours integration time. It was taken with my Esprit 150. 

The Iris is a reflection nebula in the constellation Cepheus. The light from the very bright central star is scattered by the surrounding dust giving it a distinctive blue colour. Although not designated as an emission nebula, you can also see reddish regions close to the central star which indicate the presence of ionized hydrogen. 

Interestingly, if you look at http://www.starrywonders.com/irisst8300.html  it states that the Iris Nebula is often mislabeled as the open star cluster NGC 7023, which, apparently, can be seen through the triangular shaped nebula region.  Since the red/yellow stars within (or behind) the nebula look remarkably similar to those in the triangular portion, I'm a little unclear on the extent of the open cluster. I've also attached an annotated image from Pixinsight which suggests that the star cluster (assuming NGC7023 is the star cluster....) is a more extensive, or has Pixinsight simply mislabeled the star cluster as the Iris Nebula ?

Alan

[SteveA]

Nice image Alan......not so sure I've come across this one myself before, but it is a nice target. You are right though...there does seem some confusion over the designation of this object, other online sources seem to designate the star cluster as NGC 7023..

Steve

[david_taurus83]

My last target, though my result is nowhere near as good as yours. I only managed 3 hours worth on a dslr.

[alan4908]

17 hours ago, SteveA said:

Nice image Alan......not so sure I've come across this one myself before, but it is a nice target. You are right though...there does seem some confusion over the designation of this object, other online sources seem to designate the star cluster as NGC 7023..

Steve

Thanks for the comment Steve.  Yes - quite a bit of confusion on the open cluster identification name. 

16 hours ago, david_taurus83 said:

My last target, though my result is nowhere near as good as yours. I only managed 3 hours worth on a dslr.

For DSO objectives I generally find that I need at least 7 hours to adequately capture dust and details. However, normally, I'd go for even higher integration times.  

I do take c3 hours images, however, these are normally for relatively bright objects like star clusters.

Alan

[alan4908]

After a little more digging on the subject of object reference names: a very good summary of the naming confusion over the Iris Nebula can be found in the book Deep Sky Companions: The Caldwell objects by Stephen James O'Meara.  According to this book: the confusion started in 1931 when the Swedish astronomer Per Collinder incorrectly listed NGC7023 as a star cluster. According to this reference, NGC7023 is the Iris Nebula and the star cluster should termed Collinder 429. Which sounds very reasonable. 

At this point, I think I should have stopped digging, since looking since in Wikipedia, it states that Collinder 429 does not exist....https://en.wikipedia.org/wiki/Collinder_catalog#Notable_objects 

Oh well....

Alan