This is my 2018 version of the beautiful region around the Cone Nebula in Monoceros. When I first imaged this last year I was surprised at how much this area glows in Hα. This version has Hα mapped to R, SII mapped to G, and OIII mapped to B in an attempt to get something approximating true colors. I had a lot of wind while acquiring the Hα, and lots of differential flexure between the imager and guider made the 10-minute subs used here challenging, so this is a case where using higher gain with shorter exposures might have been better. I acquired RGB data as well but didn’t end up using any of it in this image (I may try and process a HαRGB version later). I also tried HGB and HGO, but none of those looked as good to me as the images the fully narrowband combinations produced. The Hubble palette version exhibits variations in the chemical makeup, nicely showing why this set of color choices is scientifically useful. No matter what I tried, I could not get the blues in the Fox Fur Nebula to show up (well, they sort of show up in the Hubble palette). I guess maybe that needs real LRGB.

Date: 15, 17, 23 Jan 2018

Subject: Cone Nebula / Christmas Tree Cluster Region of Monoceros

Scope: Tamron 135 mm f/2.8 lens stopped to f/4

Filters: ZWO 31 mm diameter unmounted Hα, SII, OIII (7 nm bandpass), R, G, B

Mount: EQ-6 (EQMOD 2.000j)+PEC

Guiding: Orion 9x50 Finder/Guider + DSI IIc +PHD 2.6.4.5 (Win 10 ASCOM) using predictive PEC algorithm

Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21

Acquisition: Sequence Generator Pro 3.0.0.5

Exposure: 31x600 Hα, 20 x 600 SII, 15x600 OIII

Stacking: Neb 4.1.6, dark+flats, trans+rot align, Nebulosity 1.5σ stack and align.

Processing: StarTools 1.4.328: Used StarTools’ “Wipe” module to correct for vignetting remaining after flat correction, then aggressively stretched and deconvoluted each channel separately in StarTools. Aligned the processed layers in Nebulosity then combined in Photoshop using Annie’s Astro Actions’ RGB module with Hα assigned to R, SII to G, and OIII to B. I then used Hα as luminance and played with the channel mixer to adjust the colors to my liking. AstroFrame.