This was a difficult image to get mostly because there have been forest fires in the mountains all around me, so even on nights that should have been clear we had terrible smoke. I tried a lot of new things with the processing, especially in efforts to add RGB stars to the image. I found that duplicating the layer and blending the second layer as “color dodge” really brought up the intensity of the nebulosity, so I tried that but decided in the long run that it blew out too much detail. I tried the same thing on the RGB star layer, with a little better results. Ultimately in my favorite version I left the star layer as it was except boosted the saturation, and put the result over the SHO layer, then added a “hide all” layer mask to the RGB star layer. Finally, I pasted the RGB star layer into the layer mask and blended “normal” to add the RGB stars without messing with any of the rest of the SHO layer. I blurred the star layer a bit to keep the stars from looking quite as harsh. This is my favorite version of the result.

Date: 12-29 Sep 2018

Subject: Melotte 15, in the Heart Nebula

Scope: AT8IN+High Point Scientific Coma Corrector

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

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

Guiding: Orion Thin Off-axis Guider + DSI IIc +PHD 2.6.5 (Win 10 ASCOM)

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

Acquisition: Sequence Generator Pro 3.0.2.94

Exposure: 44x300 Hα, 48x300 SII, 47x300 OIII, 20x180 R, 20x180 G, & 20x180 B

Stacking: Deep Sky Stacker 4.1.1 (64-bit) dark+flat (no bias), κ-σ stacking with κ = 1.5.

Processing: StarTools 1.4.332: Cropped Hα but did not wipe, then stretched, applied HDR (optimize), masked out the “fat” stars, aggressively deconvoluted, then did untrack denoise. Followed essentially the same procedure for SII and OIII. Combined SHO in Photoshop using Annie’s Astro Actions, and played with the color balance to get it roughly how I thought it should look. I ended up with several different combinations I liked. Combined R, G, & B in StarTools. Cropped with no wipe, developed, HDR optimized, and applied default color module settings. Denoised without any deconvolution. Struggled to add RGB stars as described above. AstroFrame.