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M101, Pinwheel Galaxy, LRGB, 12-13 Apr 2017

Technical card

Resolution: 4632x3472

Dates: April 12, 2017April 13, 2017

ZWO Blue 31 mm: 22x180" -20C bin 1x1
ZWO Green 31 mm: 20x180" -20C bin 1x1
ZWO Luminance 31 mm: 90x180" -20C bin 1x1
ZWO Red 31 mm: 20x180" -20C bin 1x1

Integration: 7.6 hours

Avg. Moon age: 15.92 days

Avg. Moon phase: 98.26% job: 1537470

RA center: 211.246 degrees

DEC center: 54.608 degrees

Pixel scale: 0.860 arcsec/pixel

Orientation: -88.567 degrees

Field radius: 0.691 degrees

Locations: Mapleton Lateral Observatory, Mapleton, Utah, United States


Way too much Moon for a really good image, but the sky was very clear and I wanted to test the modifications I've made to MyFocuserPro (redid the wiring, updated the code and ASCOM driver, adjusted tension on the focuser). I also upgraded to the newest versions of EQMOD and Sequence Generator Pro, so there were lots of changes. After making a good meridian flip, the run failed while attempting to autofocus for the blue filter, apparently because of an imager download hang. I got the B data and more luminance the next night without hanging too badly. The focuser adjustments seemed to help because I got good autofocus each time I used it (as long as I didn’t get a download failure). I think I like the color balance I get using LRGB filter techniques better than those I got with the one-shot color camera. There are quite a few faint fuzzies in this part of the sky. I'll frame this a little differently next time, but I was trying to pick up some of the fuzzies.

Date: 12-13 Apr 2017
Subject: M101, Pinwheel Galaxy
Scope: AT8IN + High Point Scientific coma corrector
Filters: ZWO 31 mm diameter unmounted L, R, G, B
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: Orion Thin Off-axis Guider + DSI +PHD (Win 10 ASCOM) using predictive PEC algorithm
Camera: ASI1600MM-Cool, -20 °C, Gain 0 Offset 10
Acquisition: Sequence Generator Pro
Exposure: 90x180 L, 20x180 R, 20x180 G, 22x180 B
Stacking: Neb 4.1.5, flats & darks, trans+rot align, Nebulosity 1.5σ stack and align.
Processing: StarTools 1.4.327. Aggressively stretched and deconvoluted the luminance. Combined RGB in Neb 4 and stretched, color balanced, and sharpened in StarTools. Layered luminance over RGB in Photoshop CC 2014, boosted the saturation a little, used Carboni’s Astronomy Tools deep space noise reduction, did a little layer masked unsharp masking on M101, and a little layer masked levels to get rid of some sky glow, topped off with AstroFrame.



David Dearden

Sky plot

Sky plot


M101, Pinwheel Galaxy, LRGB, 12-13 Apr 2017, David Dearden

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