I first imaged this in RGB a couple of years ago, and was thrilled with the result at the time. I liked the combination of colors with bright stars showing diffraction spikes. I had to process this extensively, and the data were a bit grainy even after long exposure, but this is still one of my favorite images:
Found the Christmas Tree Cluster on the first try in the guide scope. It is easily visible at 1 s exposures, and the star at the "trunk" is especially bright. I'm battling the guiding a bit tonight, but I'm happy to be out as this is the first clear night we've had in about a month. CCD is at 2 °C. Decided to stop & check focus after 16 subs, and found it was way off. It is sure nice to be able to use Nebulosity fine focus and Shoestring Focus to fix things like this from indoors at mid-run. CCD temperature dropped during the run. I imaged until this got into the Spanish Fork light pollution dome a bit too far.
Date: 1 Feb 2013
Subject: NGC 2264, Cone Nebula
Scope: AT8IN+Antares 0.5x telereducer
Filter: None
Mount: CG-5 (Synta motors)
Guiding: 9x50 Finder/Guider + DSI Ic + PHD 1.14.0
Camera: DSI IIc (no chiller, T = 2 °C to -2 °C)
Acquisition: Nebulosity 3.1.3, no dither
Exposure: 45 x 300 s
Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack.
Processing: Neb 3 crop. StarTools 1.3 Develop, HDR:Reveal, Sharp, Deconvolute, Track, Magic:Shrink, Magic:Tighten, Life:Moderate, Rotate:90°. CS6 Astronomy Tools increase star color, AstroFrame.
Because I've now seen many examples of picking up much more detail in Hα light than you can see in unfiltered RGB, I've been looking forward to imaging this object in Hα, and finally got a chance on the 31st of Jan. this year. Unfortunately, the Moon was nearing full and was quite close by on that night, but I thought maybe it wouldn't affect my narrowband imaging so I went ahead. The result didn't show as much detail as I had hoped it would, but still showed more than I could see without a filter. This is an animated GIF transitioning between grey scale and false color.
Synched on Betelgeuse because my Telrad is aligned well enough and I needed a bright star to focus on anyway. Used the PicGoto and as usual was right on target. A lot of Moon, very nearby; it was causing horrible shadows in my guide scope. Maybe I should have chosen a target a bit farther from the Moon. But I went ahead anyway because I haven't had many clear nights lately. I'm testing my new butyl rubber-tape-wrapped-connection USB cabling and it worked beautifully: no disconnects! (Admittedly, I need to test longer before I declare victory on this one). Imaged up to the meridian with relatively poor guiding performance, did a meridian flip and readjusted my counterweights, then continued. Used the Astrotortilla synch this time because my Telrad was frosted over and was at an awkward angle; it worked fine after initially getting a bad goto because I forgot to uncheck "inverted" on the PicGoto software after doing the flip. Guiding after the flip was much better. Started getting clouds immediately after flipping, but as I was heading to bed it looked like they were dissipating. Did a set of sky tee shirt flats in the morning. You can see the cone in these images but not much other detail in the nebulosity until processing brought a bit more out. I may want to try this again when the Moon is not so near just so I can compare how much it affects Hα. Not enough data; still pretty noisy.
Date: 31 Jan 2015
Subject: NGC 2264, Christmas Tree Cluster/Cone Nebula
Scope: Orion ST80 + Antares 0.5x telereducer
Filter: Baader 7 nm Hα
Mount: CG-5 (Synta motors, PicGoto Simplificado)
Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.4.1 (Win 7 ASCOM)
Camera: DSI IIc no cooling (about 0 °C)
Acquisition: Nebulosity 3.2.2, no dither
Exposure: 24x600 s
Stacking: Neb 3, bad pixel map, bias included, 33 flats, extract R, histogram match, square, trans+rot align, 1.5 SD stack.
Processing: StarTools 1.3.5.289 Crop; Develop 70.43%; HDR:Optimize; Life:Less=More; Track 4.3 pix; Magic 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools Deep space noise reduction; layer masked space noise reduction; Hα false color black space; Astroframe; assemble into animated GIF.
So I decided to try again on a darker night and see what effects the Moon had on the image. It turns out the Moon had a huge effect, so I guess I've learned another lesson: watch out for a bright nearby Moon, even if you are doing narrowband imaging! I think you'll be able to see the difference easily:
Wanted to get a new set of images to compare with the 31 Jan set that was taken right next to a bright Moon (this would give me an idea about how much the Moon matters). Synched on Betelgeuse and used the PicGoto; right on, as usual. Needed to refocus periodically, and the mount appeared to be suffering from stiction. Imaged up to the meridian, performed a flip, re-synched on Betelgeuse, reacquired, continued until the Cone/Christmas Tree set. The Moon matters a lot when it's as close as it was on 31 Jan 2015. This image is far better. HαRRGB coming
Date: 11 Feb 2015
Subject: NGC 2264, Christmas Tree Cluster/Cone Nebula
Scope: Orion ST80 + Antares 0.5x telereducer
Filter: Baader 7 nm Hα
Mount: CG-5 (Synta motors, PicGoto Simplificado)
Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.4.1 (Win 7 ASCOM)
Camera: DSI IIc no cooling (about 0 °C)
Acquisition: Nebulosity 3.3, no dither
Exposure: 38x600 s
Stacking: Neb 3, bad pixel map, bias included, 30 flats, extract R, histogram match, square, trans+rot align, 1.5 SD stack.
Processing: StarTools 1.3.5.289 Crop; Autodev; HDR:Optimize; Deconvolute 4.5 pix; Track 2.5 pix; Photoshop CC 2014 + Carboni Astronomy Tools Deep space noise reduction; Hα false color black space; Astroframe; assemble into animated GIF.
Finally, I combined the original RGB data from 1 Feb 2013 with my new Hα from 11 Feb 2015 (I didn't use any of the 31 Jan data for this). I aligned the two images using Nebulosity 3.3's "translate, rotate, and scale" procedure, then mixed the R channel from the RGB with the Hα, 25% and 75%, respectively. This HαR became the new R channel in the final image; I dialed it up 130% in the CS6 channel mixer to mitigate the "blue star" problem I tend to have. I also used the HαR as a luminance layer for the final image, at 60% opacity. I really love the colors in the result, although this blended version does lose some of the detail that can be seen in the Hα image (someday I'd love to get a monochrome camera and a full set of filters so I could have it all). Here's the full-color version:
