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sh2-155 "Cave Nebula" in Cepheus, 





    
        

            Daniel.P
sh2-155 "Cave Nebula" in Cepheus

sh2-155 "Cave Nebula" in Cepheus

Acquisition type: Electronically-Assisted Astronomy (EAA)

Technical card

Resolution: 4608x3450

Dates:Sept. 13, 2019Sept. 14, 2019Sept. 16, 2019Sept. 17, 2019Sept. 18, 2019Sept. 20, 2019

Frames:
AstroDon 5nm Ha filter: 6x600" (gain: 139.00) -12C bin 1x1
AstroDon 5nm Ha filter: 12x600" (gain: 139.00) -15C bin 1x1
AstroDon 5nm Ha filter: 4x600" (gain: 139.00) -9C bin 1x1
AstroDon 5nm OIII filter: 9x600" (gain: 139.00) -12C bin 1x1
AstroDon 5nm OIII filter: 14x600" (gain: 139.00) -15C bin 1x1
AstroDon 5nm OIII filter: 3x600" (gain: 139.00) -9C bin 1x1
AstroDon 5nm SII filter: 4x600" (gain: 139.00) -12C bin 1x1
AstroDon 5nm SII filter: 13x600" (gain: 139.00) -15C bin 1x1
AstroDon 5nm SII filter: 3x600" (gain: 139.00) -9C bin 1x1
ZWO new G: 5x120" (gain: 50.00) -12C bin 1x1
ZWO new R: 5x120" (gain: 50.00) -12C bin 1x1

Integration: 11.7 hours

Darks: ~15

Flats: ~3

Flat darks: ~25

Avg. Moon age: 17.17 days

Avg. Moon phase: 89.19%

Mean SQM: 18.70

Mean FWHM: 3.00

Astrometry.net job: 2975196

RA center: 344.002 degrees

DEC center: 62.404 degrees

Pixel scale: 0.906 arcsec/pixel

Orientation: 359.753 degrees

Field radius: 0.724 degrees

Locations: Duc, Prayssas, Lot et Garonne, France

Data source: Backyard

Description

September session : I had 2 weeks of nearly perfect weather but ... under the full moon ! So I tried to see how my NB filter will do under the full moon.

This image was obtained using exposures spanning over six nights !
Each night consisted of multiple targets and meridian flips (IC1805, M31x2 and M33). Everything is now working fully unattended.
One interesting thing, is that during night of 16 september, the sky was blocked by clouds at the beginning of the night. I therefore left my session active, but under "recovery mode" in SGP. It automatically resumed during the night when the clouds cleared (3 times actually).
The interesting thing about automation is that I was able to image targets when they are close to the meridian and use the full duration of the night (here around 10hours) by switching targets.

The processing was done in PI as follow :
For each S, H, O, R, G, B channels :
- Images Calibration (Dark Substraction)
- Cosmetic Correction
- Image Registration
- Image Integration
- Mure Denoise (for SHO only)
Then :
- Create SHO image
- Create RGB image and color balance and color sat (to be used to color stars in SHO)
- Color balance on nebula
- Deconvolution masked with 2.0 pixel psf
- Background extraction
- SCNR (G neutral and min 0.85)
- Going NL using HT
- Color Saturation masked (and desaturate bkg)
- Color Saturation masked using stars to desaturate stars
- Apply "a" & "b" color channels of the RGB image under star mask
(this is to apply natural color to the stars)
- Redo Color Balance on stars
- Local Histogram Equalisation masked (slight)
- TGV denoise (no mask)
- Local Histogram Equalisation (at 90 and 250 px scales)
- Deflip
- Crop

Final image adjustments performed in Iphoto on Imac :
- levels adjustments
- adjust color looking using "selective color"

Comments

Author

Daniel.P
Daniel.P
License: None (All rights reserved)
650
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Revisions

  • Final
    sh2-155 "Cave Nebula" in Cepheus, 





    
        

            Daniel.P
    Original
  • sh2-155 "Cave Nebula" in Cepheus, 





    
        

            Daniel.P
    B
  • sh2-155 "Cave Nebula" in Cepheus, 





    
        

            Daniel.P
    C
  • sh2-155 "Cave Nebula" in Cepheus, 





    
        

            Daniel.P
    D

B

lower contrast

C

upper part

D

Zoom on IL Cep variable star and objet at the bottom of the image

Sky plot

Sky plot

Histogram

sh2-155 "Cave Nebula" in Cepheus, 





    
        

            Daniel.P