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NGC 281, Pacman Nebula, 20 Sep 2012, David Dearden

NGC 281, Pacman Nebula, 20 Sep 2012

Equipment

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Acquisition details

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Description

The Pacman Nebula was easy to find because it is easy to line up on the bright stars of Cassiopeia. The smoke is much less tonight. Little wind, and guiding looks good so far. I have a new power supply for the chiller, so I'm running at 1.53 A, 7.0 V, 9 °C. There's a lot of sky glow in my 300 s subs, but for now I'll stick with them and see how they turn out. Maybe I need the UHC-S filter for this part of the sky. Also, it is just barely full dark so I expect things will get better. High dither, settling at 0.5. Collimated with the laser collimator through the coma corrector, but did a star test and was not happy, so recollimated on a defocused star, centering the secondary's shadow. I hope that works.

In the revision I used two layers, one for sharpening and one for removing background noise. In the sharp layer I used an unsharp mask of 2 pixels. In the denoise layer I applied deep space and space noise reduction. I applied a hide all layer mask to the sharp layer and just traced the edges of features within the nebula, Gaussian blurred the mask about 3 pixels, and flattened. To the flattened image I did a color range select on the nasty green background, created a saturation adjustment layer, and desaturated it. Looks better, I think.

In the last revision, I used StarTools and worked pretty hard on this image. Ultimately I used as much sharpening as I could followed by Life:Isolate, and still applied a little layer mask trickery in CS6 at the end.

Date: 20 Sep 2012

Subject: NGC 281, Pacman Nebula

Scope: AT8IN+High Point Scientific coma corrector + 0.5x Antares telereducer

Filter: None

Mount: CG-5 (Synta motors)

Guiding: Orion ST80 + DSI Ic + PHD

Camera: DSI IIc, Cooled 1.5 A 7.0 V (5-9 °C)

Acquisition: Nebulosity 3.1.2, high RA-only dither

Exposure: 34 x 300 s

Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack

Processing: Digital development with weak sharpening, Keller stretch middle of histogram, power stretch, star reduction, saturation boost in Neb 3; CS6 curves & levels, Astronomy Tools deep space, space noise reduction. Star color enhance, desaturate greens, finally “less crunchy more fuzzy” in Astronomy Tools.

Comments

Revisions

  • NGC 281, Pacman Nebula, 20 Sep 2012, David Dearden
    Original
  • NGC 281, Pacman Nebula, 20 Sep 2012, David Dearden
    B
  • NGC 281, Pacman Nebula, 20 Sep 2012, David Dearden
    C
  • Final
    NGC 281, Pacman Nebula, 20 Sep 2012, David Dearden
    D

Histogram

NGC 281, Pacman Nebula, 20 Sep 2012, David Dearden