Celestial hemisphere:  Northern  ·  Constellation: Canes Venatici (CVn)  ·  Contains:  NGC 4627  ·  NGC 4631  ·  NGC 4656  ·  NGC 4657
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NGC 4631 & 4656, Whale & Crowbar Galaxies, LRGB, 23-24 Apr 2018, David Dearden
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NGC 4631 & 4656, Whale & Crowbar Galaxies, LRGB, 23-24 Apr 2018

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NGC 4631 & 4656, Whale & Crowbar Galaxies, LRGB, 23-24 Apr 2018, David Dearden
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NGC 4631 & 4656, Whale & Crowbar Galaxies, LRGB, 23-24 Apr 2018

Equipment

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Acquisition details

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Description

With the ASI1600MM-C I have a much bigger field of view than before, making shots like this one feasible. I had a bit of wind and some guide camera misbehavior (USB connection dropping) but very clear skies while acquiring the data; eventually I switched the guider to my USB3 hub and that problem went away (crossing my fingers on that one). There seems to be something chemically interesting going on in the core of the Whale, as the color there is unusual. As with my recent Sombrero image, the galaxies here stand out very nicely against the star field with no special effort to reduce the stars or bring out the galaxies; I’m just using my standard workflow. I tend to favor a lot of saturation in my processing; maybe it is too much this time. The Moon is waxing and making these LRGB images more difficult.

Date: 23-25 Apr 2018

Subject: NGC 4631 & 4656, Whale & Crowbar Galaxies

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 Ic +PHD 2.6.4.dev10 (Win 10 ASCOM)

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

Acquisition: Sequence Generator Pro 3.0.1.0

Exposure: 90x180 L, 23x180 R, 30x180 G, 18x180 B

Stacking: Deep Sky Stacker 4.1.0 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5.

Processing: StarTools 1.4.332: Did RGB combination using StarTool’s LRGB module. Binned 2x2 in StarTools. Used StarTools’ “Wipe”, then aggressively stretched and deconvoluted L and RGB separately in StarTools. Went with the default colors from StarTools’ color module. Combined L with RGB in Photoshop. Used Astronomy Tools’ increase star color, some additional deep space & space noise reduction, followed by “less crunchy more fuzzy”, AstroFrame.

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NGC 4631 & 4656, Whale & Crowbar Galaxies, LRGB, 23-24 Apr 2018, David Dearden