Starting on a night with a lot of moonlight and after finishing with another target, I began acquiring Hα for the Tulip Nebula. I finally got an absolutely beautiful, dark night to get the RGB and more Hα, with this result. I combined starless Hα with the R channel to produce an enhanced R channel, and used Hα combined with a greyscale version of the RGB as luminance. I thought I might have captured the companion star of Cygnus X-1, the famous black hole, but it turns out that is just off the top of this frame. I opted for a lot of saturation in this image, because the star field here is very pretty.

Date: 26 May, 12 Jun 2018

Subject: Sh2-101, Tulip Nebula

Scope: AT8IN+High Point Scientific Coma Corrector

Filters: ZWO 31 mm diameter unmounted Hα, R, G, B

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

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

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

Acquisition: Sequence Generator Pro 3.0.2.82

Exposure: 58x300 Hα, 20x300 R, G, & B

Stacking: Deep Sky Stacker 4.1.1 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5.

Processing: StarTools 1.4.332: Combined R, G, and B in StarTools. Binned 2x2, cropped, wiped, developed, HDR. No deconvolution. Turned off tracking to smooth fairly agressively. Binned Hα 2x2, cropped, wiped, and used Autodev followed by HDR. Masked out the “fat” stars and used light deconvolution followed by untrack smoothing. Healed out the stars to produce a starless version. Combined this (after some smoothing and levels to darken the background) with the R channel from the RGB and used the result as the new R channel. Combined the full Hα (after some smoothing) 50% with a greyscale version of the RGB to form a luminance layer. Used curves to back off the resulting L a little, and enhanced the RGB a little. Some layer masked Unsharp Mask to bring out a bit more detail in the nebula. Played with Vibrance, Saturation, and Levels to get the colors where I liked them. AstroFrame.