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Sh2-155, Cave Nebula, HαRRGB, 12 Sep 2014+28 Sep 2016

Technical card

Resolution: 762x585

Dates: Sept. 12, 2014Sept. 28, 2016

Baader Planetarium Ha 7nm 1.25": 11x600"
Baader Planetarium UHC-S Filter: 14x600"

Integration: 4.2 hours

Avg. Moon age: 22.90 days

Avg. Moon phase: 45.18% job: 1273720

RA center: 344.379 degrees

DEC center: 62.509 degrees

Pixel scale: 3.286 arcsec/pixel

Orientation: -179.890 degrees

Field radius: 0.438 degrees

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


Tried to add some OSC RGB to go with Hα from 2014, but the session failed due to image download issues a little after I went to bed. Hence, I didn't get as much data as I should have. I'm trying to learn how to add the RGB stars back into the HαRRGB to preserve some of their color and brightness without overwhelming the image. Still learning how to do that, but this is a current attempt, and it is dramatically better than my first attempt on this target in 2012 so I’m happy to see the progress.

Date: 28 Oct 2016
Subject: Sh2-155, Cave Nebula
Scope: AT8IN + Antares 0.5x focal reducer
Filter: Baader Planetarium UHC-S
Mount: EQ-6 (EQMOD)+PEC
Guiding: Orion ST80+Antares 0.5x focal reducer +DSI Ic+PHD (Win 10 ASCOM)
Camera: DSI IIc, no chiller CCD ~10 °C
Acquisition: Sequence Generator Pro with Nebulosity 4.1.1 ASCOM camera driver (Win 10)
Exposure: 14x600 s (OSC) + 11x600 s (Hα)
Stacking: Neb 4, bad pixel map, bias included, 33 flats, match histograms, trans+rot align, Neb 40-60%tile stack.
Processing: StarTools 1.4.305: Crop; Wipe; Develop: 79.19%; HDR:Optimize; Color:Scientific, 122% saturation; Deconvolute: 2.4 pix; Life:moderate; Track: Smoothness 87%, 4.5 pix; Magic, shrink 1 pix. Heal out stars per online StarTools tutorial and save. Photoshop CS6 + Astronomy Tools: Deep space noise reduction; Use HαR for R and for Luminance; boost R channel; Layer on RGB stars using Color Dodge; Increase star color; Levels; Hue/Saturation adjustments a couple of times; Layer masked local contrast enhance; Liquify/pucker; Astroframe.



David Dearden

Sky plot

Sky plot


Sh2-155, Cave Nebula, HαRRGB, 12 Sep 2014+28 Sep 2016, David Dearden