Welcome to the Fall Semester and to the CN October Observing Challenge … !
Frankly, some of the recent ‘Challenges’ have been a bit of hard work and I had been longing for some easier observing this month with some fun objects, especially ones that fall into my limited sky window and that don't keep me up too late. Then Errol gave me some great news - he reminded me it was already ‘my month’ (again) to issue the Challenge... so now, I can make everything as easy as I had hoped it would be.
So, here we go, we have 6 lovely nebulae and 4 easy Galaxies to observe and learn from. Maybe a couple are a bit low and maybe a couple others might be easier later at night but, generally, they’re super manageable and, I hope, fun to go after…one is even a bit ‘different’ but don’t let that deter you.
Nebulae:
I think I learned last month that nebulae are the most fun when you use a FILTER. Most of us who take the easy way out, use a ‘dual band’ filter which haul in the hydrogen alpha and oxygen photons. The hard core folks (you know who you are) use straight Ha with narrow bandwidths around 4-7nm. Last month, I fell into a third category of folks who were too lazy to change their cameras from whatever tasks they had last been doing.
I think it would be interesting to see folks experiment a bit and post both color images with/without dual band filters and mono images with/without Ha filters – whatever combination is available and of interest to you. Whatever approach you take, could I encourage you to run your integrations much longer than you might normally do. I was amazed last month by how much detail I could tease out of some of the targets with a straight mono camera if I just gave it more time and some histogram fussing. Anyway, here's this month's target list:
N1 Eastern Veil Nebula (NGC 6995) - makes bit of a transition from last month’s West Veil and a proper warm-up to this month’s Challenge
N2 Hubble’s Variable Nebula (NGC 2261) – would be fun to post several images showing the change in brightness over the month.
N3 Cave Nebula (SH2-155) – will reward the folks lucky enough to have Ha filters but 'dual-banders' will also do well.
N4 Bubble Nebula (NGC 7635) – my total favorite and its worth lots of time and fussing to reveal the full bubble 'circle'.
N5 Helix Nebula (NGC 7293) – here’s a case where time and patience will be rewarded – lots of detail, knots and globules to see.
N6 Pacman Nebula (NGC 281) – this will like your dual band filter and you’ll like all the dust, knots and globules it reveals – be patient, take time and tease it out.
Galaxies:
For most of us in suburban locations it’s a ‘toss-up’ whether we can get more brightness and detail by using a UHC (Ultra High Contrast) filter or just go bare – no filter at all. I’ve heard also that an AP-type luminance filter can work since it lets lots of starlight through but blocks some of the pesky, man-made photons. No matter what, depending on your target and your aperture, generous integration time, as with nebulae, will bring out details and a stronger sense of the galaxy's structure. Try going for less gain and more total time.
G1 Barred Spiral in Pegasis (NGC 7479) – at magnitude 10.9, this one is only going to reveal its sweeping outside arms and subtle, wispy short, interior ones with a fair amount of time, pretty-low gain and patient fussing with the black and mid level histogram sliders. Zoom in a lot to see the impact of subtle adjustments to these and the color sliders.
G2 Edge-on Galaxy in Pegasis (NGC 7814) – I’ve never observed this one but I bet that, for most of us, we start out getting just a fuzzy oval glow with a bright spot at the galactic core. So, our challenge is getting enough contrast between the glow of the overall oval so that we can bring out the dark central lane to highlight the core’s central ‘hot spot’. Sounds ok, might even be right.
G3 Pinwheel Galaxy in Triangulum (NGC 598) – rotate the filter wheel back to apply the dual band filter to M33 and you’ll be pulling in the reds and green-blues of star formation, a specialty of this galaxy. There are loads of both warm clouds of formation and cool clouds of mature stars, clumped together from our point of view. Give it time, have a coffee and let the details build up before making your final tweeks to the histogram and hitting ‘Save as…’.
G4 NGC 206 (OB 78) – this ‘star cloud’ is a long way gone - in the midst of the Andromeda Galaxy’s spiral arm structures. The final challenge this month is to capture an image of a few ‘individual stars’ within NGC 206 which is, in turn, within M31 – YOU CAN DO THIS ! ….but you probably need decent skies, a little help (see below) and a bit of aperture – not too much though, my 8” F4 was enough. I’ve attached an article, Resolving Andromeda - How to See Stars 2.5 Million Light-Years Away, by Bob King from S&T October 2016. Its a good read and will point out the way to find individual stars in NGC 206.
Hope you enjoy clear skies this October !
Gary
