IOM August 2008 – the Cave nebula in Cepheus

It’s still not great imaging during August due to the continuing light evenings and early mornings, and I see from my notes that it is still getting on for 11.00 p.m. before it is worth setting up for an imaging session 🙁

However, needs must, and we do our best given the circumstances, so what object do I choose for the Imaging Object of the Month for August?  As I said last Month, we could still choose an object in Cygnus, and we could in fact keep going with our “mega-imaging” project if we started one last Month.  But I fancy choosing something a bit different, and in a part of the sky I don’t spend a lot of time imaging in.  For August 2008 I’ll pick the Cave nebula in Cepheus.

The Cave nebula [Sharpless 2-155, Caldwell 9] is a fascinating region of space in Cepheus containing dark nebulosity, emission nebulosity and reflection nebulosity – it is very busy – and a very rewarding imaging target.  It is also rather faint and once again requires reasonably long sub-exposures of around 10-minutes for RGB with my system.  You will also want to take some narrowband H-alpha to bring out all the faint emission nebulosity in the area.

You don’t need a wide field imager for this object, and if you’re specifically interested in the Cave nebula itself you’re better off with a narrower field of view than I get from the Sky 90/M25C combination.  In fact the old Hyperstar setup had an almost ideal field of view for the Cave coming in at around 1.0 x 0.75 degrees.

Don’t worry – we’re about to leave our most difficult imaging months and September will once again bring dark nights to us at a more reasonable hour.  All we then need is for the cloud (and Moon) to keep clear.

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