A Teddy Bear in Hydrogen Alpha

The skies finally cleared last night so I decided to get my gear out. The Moon is about at 1st quarter and I've been itching to try the Hα filter anyway, so I decided to image a new (to me) object, Sh2-199, aka the Soul Nebula. To me it looks more like a teddy bear viewed in profile (and I'm not sure what a soul looks like; I think it gets that name mostly because the other emitting part of the same gas cloud looks like a heart, and "heart and soul" go together).

Another thing I've been wanting to try is combining my Hα filter with my Orion ST-80 refractor. The ST-80 gives me a significantly wider field of view than I can get with my bigger 8" reflector, and at f/5 it is still reasonably fast, especially when I add a focal reducer to widen the field of view. Even with the reducer, I still couldn't quite fit the whole Soul. Using a reducer on this scope unfortunately magnifies its optical flaws, which are significant, but here's where being cheap (i.e. using a small-chip camera) helps a little. The optical aberrations are worst around the edges of the field of view, and my small imaging chip only samples the center. So that helps some. In addition, this rig is quite light, so in principle my telescope mount should be able to handle it more easily. In practice, I don't seem to get any better performance than I get with the heavy AT8IN reflector on the mount. Finally, at this imaging scale my guiding performance can be lousy and I can't tell.

So here's the Soul Nebula. The "teddy bear" is lying face down, with his head to the right. IC 1848 is the open cluster in the torso of the bear. Once again, I'm amazed at what I can pick up with that Hα filter. I'm excited to try imaging things like the Horsehead, Flaming Star, and Tadpole Nebulae with it, and those will be in position shortly.

First observation of the Soul Nebula; I chose it over the Heart because it looks like it will fit in my field of view slightly better. This is also my first use of the Hα filter with the ST-80 scope. Synched from ε Cas and the PicGoto put the Soul in the field of view on the first try. It took me a while to recognize I was there because the cameras on the ST-80 are oriented 180° from the orientation I use on the AT8IN and I didn't realize that at first. Cool, clear, calm evening. Chiller at 2.5 A, currently 3.5 °C. Guiding looks good enough for this imaging scale. Focusing was hard; I did it through the filter looking at the Moon and hope that will be adequate. My guide scope image is blurry: either out of focus or there's dew on the objective (I think probably I messed up the focus in moving the guider to the ST-80, but they say PHD performs a little better when a little out of focus. We'll see.) Very little differential flexure with this setup until the mount started bumping; then it jumped pretty well.

Date: 1 Oct 2014
Subject: Sh2-199 / IC 1848, Soul Nebula
Scope: Orion ST-80 + Antares 0.5x telereducer
Filter: Baader Hα
Mount: CG-5 (Synta motors, PicGoto Simplificado)
Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.3.1 (Win 7 ASCOM)
Camera: DSI IIc chiller at 2.50 A, 3.5 to -1 °C
Acquisition: Nebulosity 3.2.1, no dither
Exposure: 39x600 s
Stacking: Neb 3, bad pixel map, bias included, no flats, OSC red channel extract, normalize, square, trans+rot align, 1.5 SD stack.
Processing: StarTools 1.3.5.289 Crop; Autodev; HDR:Optimize; Deconvolute 3.0 pix; Life:Less is more; Track Grain size 5.0 pix, Smoothness 50%; Magic:Shrink 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools Hα false color; Astro Frame.