One motivation for this image was to compare with the image I took a year ago, which was the first using the Tamron 135 mm lens; I wanted to see how much my technique and experience had changed over the last year. The new image suggests these have changed a lot. I had intended this to be HSO/SHO, but the session failed (the image download hung up) while trying to autofocus the SII filter (which was the last in the sequence) long after I had gone to bed, so it ended up being only bicolor. It looks like the weather is turning stormy at last (winter is coming pretty late this year in Utah) so I’m going with the data I have rather than wait for more clear skies. These data were tough to process because this target is quite dim, hence the original data required very extensive stretching and were consequently pretty noisy. Nearly all the structure shows up only in Hα (only the barest hint of the filaments in OIII), though I’m curious whether anything would have been visible in SII. I continue to have trouble with my Tamron 135 flats (the current ones overcorrect), so I ended up not using them and just let StarTools’ Wipe vignetting module handle things. I went back and forth a few times about how dark to make the background, and ended up leaving it fairly dark. I understand this nebula is thought to be a supernova remnant. The structure in the filaments is amazing—it looks to me more like a wad of fine spun gold with the color choices in this image, rather than spaghetti—leading me to wonder what caused it. Most likely it was just random turbulence at the time of the supernova explosion, but it is fun to speculate that maybe it was somewhat shaped by a planetary system around the star, destroyed at the time but imprinted on the remnants (now that we know that most stars do have orbiting planets). Of course I have no evidence for such romantic speculation!

Date: 19 Dec 2017

Subject: Sh2-240 (Simeis 147), Spaghetti Nebula

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

Filters: ZWO 31 mm diameter unmounted Hα, OIII (7 nm bandpass)

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

Guiding: Orion 9x50 Finder + 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 3.0.0.4

Exposure: 40x300 Hα, 36x300 OIII

Stacking: Neb 4.1.6, darks only, trans+rot align, Nebulosity 1.5σ stack and align.

Processing: StarTools 1.4.328: Used StarTools’ “Wipe” module to correct for vignetting, then stretched and deconvoluted each channel separately in StarTools. Aligned the processed layers in Nebulosity then combined in Photoshop using Annie’s Astro Actions’ HO Bicolor module. Multiple rounds of Photoshop Curves and Levels, combined with several rounds of Carboni’s Make Stars Smaller, then Deep Space and Space Noise Reduction and a few rounds of Less Crunchy More Fuzzy. AstroFrame.