2.54 ± 0.11 MLy

Here’s my 2019 attempt at M31. This is a 6-panel mosaic. Acquisition was plagued with focuser problems (because the tension was set incorrectly, it refused to move both directions so ultimately I disabled autofocusing, focused once, and went to bed). The results were so bad I threw out about half the data from the first night. Another result was there were no usable B subs for the bottom-left panel; I used synthetic blue (created in StarTools by channel interpolation) there. Nevertheless, in the end I think this image blows all my previous attempts on this very-often-imaged target out of the water. As is always the case, it would benefit from more integration time but it just takes a lot of time to get more when there are 6 panels! I know this is nothing for many of you, but this is my first try for a multi-panel image with LRGB techniques.

Date: 7-9 Nov 2019

Subject: M31, Andromeda Galaxy

Scope: AT8IN+High Point Scientific Coma Corrector

Filters: ZWO 31 mm diameter unmounted LRGB

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

Guiding: Orion Thin Off-axis Guider + ASI120MM-mini +PHD 2.6.6 (Win 10 ASCOM)

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

Acquisition: Sequence Generator Pro 3.1.0.345

Exposure: 6 panels, each 20x180 L, 15x120 R, 15x120 G, 15x120 B

Stacking: Deep SkyStacker 4.2.2 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5.

Processing: StarTools 1.6.380: For each panel, combined L, R, G, & B in StarTools, using correct exposure times to add synthetic luminance from R, G, & B. Software binned 2x2, cropped, wiped, developed ~90 %, HDR optimized (combination of “hard” and “reveal all”), used the color module with significant saturation boosting, deconvoluted, and untrack denoised. Rotated a few panels 180° to get proper relative orientation. Stitched all panels together using Microsoft Image Composite Editor. Deep space noise reduction in Photoshop, with a little attempt to mess with the color in the bottom left part of the image using a layer mask. Slight levels adjustment, followed by AstroFrame.