M12, LRGB, 19 May 2020 (David Dearden)

M12, LRGB, 19 May 2020

15,700 ly

The forecast was a bit iffy (wind and high cloud) but I decided to get my gear out anyway and I’m glad I did as the weather turned out OK. My last attempt on M12 was 4 years ago, and this is a far better image. Wikipedia indicates this globular is more loosely-packed than usual, and has fewer low-mass stars than usual; it is reported to be about 75 ly in diameter. I like the colors it displays, but as usual I’m never too certain that my representation of the colors is accurate, and these are definitely not the same as I got last time with a one-shot-color camera. The star field in this part of the sky is quite dense and rich.

Date: 19 May 2020

Subject: M12

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 + ASI120MM-mini +PHD 2.6.8 (Win 10 ASCOM)

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

Acquisition: Sequence Generator Pro 3.1.0.479

Exposure: 24x180 L, 15x180 R, 15x180 G, 15x180 B

Stacking: Deep Sky Stacker 4.2.3 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5

Processing: StarTools 1.6.394RC: Composed L, R, G, & B accounting for total integration times in creating a combined synthetic luminance. Cropped, wiped (vignette), developed (95%), HDR (reveal core), deconvoluted slightly (2 pixels), and untrack denoised. In Photoshop, some levels adjustments to darken the background followed by 1 round of Astronomy Tools’ “less crunchy more fuzzy”. AstroFrame.

Final
Original
B

B

Description: Same processing except used “reveal all” in HDR instead of “reveal DSO core”. This is perhaps a more honest representation of the dynamic range in brightness in the cluster.

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	3529169
PixInsight job	YGBIXG9JF544KIFMR0YR1PND7IYEMARJ
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	16h47m16s.47
RA (top/left)	16h44m59s.37
RA (top/right)	16h49m23s.77
RA (bottom/right)	16h49m33s.36
RA (bottom/left)	16h45m09s.27

Dec (center)	-01°56′45″.0
Dec (top/left)	-02°20′34″.8
Dec (top/right)	-02°23′43″.3
Dec (bottom/right)	-01°32′49″.5
Dec (bottom/left)	-01°29′43″.2

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