Despite the nice brightness and size of this pretty planetary nebula, the Helix is a difficult target for me because its transit altitude is only 29° above my southern horizon, viewed over a housetop. Unsurprisingly, seeing was not great. In addition, I had problems with my camera dropping downloads so I didn’t get quite as much data as I wanted. (I’m not sure what is causing this, but suspect it is the USB connections.) The original plan was to add RGB stars to the HO data, but the download issue prevented that. Finally, something has gone wrong with my calibration; if I used my bias frames, the result looked terrible so I had to stack without including the bias correction (obviously I need to shoot a new bias frame, but didn’t take the time to set everything up to do it after discovering the problem). Still, it’s a much better image of this object than I’ve gotten before so I’m happy. On the plus side, I did get to watch it rise over the side of a mountain as I was waiting to start my session. It looked really cool, quite otherworldly in a literal sense.

Date: 4-5 Sep 2018

Subject: NGC 7293, Helix/Sunflower Nebula

Scope: AT8IN+High Point Scientific Coma Corrector

Filters: ZWO 31 mm diameter unmounted Hα, OIII

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: 27x300 Hα, 24x300 OIII

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

Processing: StarTools 1.4.332: Binned both Hα and OIII 2x2 in software. Cropped, wiped (vignetting), developed, deconvoluted, and untrack denoised. Used Annie’s Astro Actions in Photoshop to do the HO bicolor combination. Dropped red (shadows) using the color balance to get rid of some red background cast. Deep space noise reduction, then AstroFrame.