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Contains:  Crescent Nebula, Crescent nebula, NGC 6888, NGC6888, Sh2-105
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NGC 6888 in HOO with OSC camera experiment, 


            Cedric Raguenaud
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NGC 6888 in HOO with OSC camera experiment

Technical card

Imaging telescopes or lenses:Skywatcher 300/1500

Imaging cameras:QHYCCD 183C

Mounts:Skywatcher EQ8 pro

Guiding telescopes or lenses:TS-Optics OAG

Guiding cameras:ZWO ASI120MM

Focal reducers:Baader MPCC Mark III Coma Corrector

Software:PixInsight 1.8 Ripley

Accessory:Home made focuser

Dates:Aug. 5, 2020Aug. 6, 2020Aug. 23, 2020

Frames:STC Dual Narrowband filter: 66x600" (gain: 16.00) -15C bin 1x1

Integration: 11.0 hours

Avg. Moon age: 12.98 days

Avg. Moon phase: 71.20%

Bortle Dark-Sky Scale: 4.00

Mean SQM: 21.57 job: 3805810

RA center: 20h 12' 4"

DEC center: +38° 20' 17"

Pixel scale: 0.826 arcsec/pixel

Orientation: 174.055 degrees

Field radius: 0.281 degrees

Resolution: 2048x1357

Locations: ORCA Observatory, Near Matha, Charente-Maritime, France

Data source: Own remote observatory


I normally shoot colour with an OSC camera because of time constraints (I don't have the clear nights to multiply by 3 the integration time). But I'd like to make SHO or HOO images too. So for this image I tested a dual narrowband filter that maps Ha to red and OIII to blue.

This is why the diffraction spikes are like morse code and alternate red and blue dashes (I don't know how the filter is built to explain it).

The processing is then a mix of colour and mono processing: colour up for calibration and until debayerisation. From there, extract the red and blue layers and process them like mono layers.

Because of weather (heat and thunderstorms) I only managed to get 2 short nights for the experiment. Ideally I'll add time whenever possible.



Cedric Raguenaud
License: Attribution-NonCommercial-ShareAlike Creative Commons


  • NGC 6888 in HOO with OSC camera experiment, 


            Cedric Raguenaud
  • Final
    NGC 6888 in HOO with OSC camera experiment, 


            Cedric Raguenaud

Sky plot

Sky plot


NGC 6888 in HOO with OSC camera experiment, 


            Cedric Raguenaud

In these public groups

STC Dual Narrowband filter images