Hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  Sh2-136  ·  VdB141
Getting plate-solving status, please wait...
sh2-136 "Ghost Nebula" in Cepheus - LRGB, 



    
        

            Daniel.P
Powered byPixInsight

sh2-136 "Ghost Nebula" in Cepheus - LRGB

Acquisition type: Electronically-Assisted Astronomy (EAA, e.g. based on a live video feed)
Getting plate-solving status, please wait...
sh2-136 "Ghost Nebula" in Cepheus - LRGB, 



    
        

            Daniel.P
Powered byPixInsight

sh2-136 "Ghost Nebula" in Cepheus - LRGB

Acquisition type: Electronically-Assisted Astronomy (EAA, e.g. based on a live video feed)

Imaging telescopes or lenses: TS Optics APO130f6

Imaging cameras: ZWO ASI1600MM-Cool

Mounts: Ioptron CEM 120 EC2

Guiding telescopes or lenses: TS Optics APO130f6

Guiding cameras: Starlight Express Lodestar X2 Autoguider

Focal reducers: TS-Optics TSFlat 2

Software: Sequence Generator Pro  ·  PixInsight  ·  PHD Guiding 2.5.0

Filters: ZWO new B  ·  ZWO new G  ·  ZWO new R  ·  ZWO new L

Accessory: ZWO EFW 31mm 8 positions  ·  QHYCCD PoleMaster  ·  Innovations Foresight ONAG  ·  USB_Focus V3 Usb Focus  ·  USB Stepper Motor Heavy Load


Dates:Aug. 2, 2019Aug. 3, 2019Aug. 4, 2019Aug. 5, 2019

Frames:
ZWO new B: 30x120" (gain: 139.00) -15C bin 1x1
ZWO new B: 17x300" (gain: 50.00) -15C bin 1x1
ZWO new G: 30x120" (gain: 139.00) -15C bin 1x1
ZWO new G: 29x300" (gain: 50.00) -15C bin 1x1
ZWO new L: 60x120" (gain: 139.00) -15C bin 1x1
ZWO new L: 68x300" (gain: 50.00) -15C bin 1x1
ZWO new R: 30x120" (gain: 139.00) -15C bin 1x1
ZWO new R: 30x300" (gain: 50.00) -15C bin 1x1

Integration: 17.0 hours

Avg. Moon age: 3.31 days

Avg. Moon phase: 13.30%

Mean SQM: 21.30

Mean FWHM: 2.60


Astrometry.net job: 2985930

RA center: 21h 16' 24"

DEC center: +68° 15' 29"

Pixel scale: 0.908 arcsec/pixel

Orientation: -179.501 degrees

Field radius: 0.721 degrees


Resolution: 4569x3430

Locations: Duc, Prayssas, Lot et Garonne, France

Data source: Backyard

Description

I spent most of these 4 moonless nights with dark sky (around 21.3 SQM) to image this nebula with LRGB filters.

17 hours is currently my longest total exposure on a single target. Stars with mag 22.5 should be visible (with SNR=5) on the image.

My AO was off, and I use multistar guiding with PHD2 directly on the CEM120EC2 mount. It worked well but apparently, I was better not using to fast corrections (it seems to interfere with the encoders work). I used typically 2 sec guide steps. My objective is to use back AO with faster guide steps.

The image is color balanced on stars.

The processing was done in PI as follow :
For each L, R, G, B channels :
- Images Calibration (Dark Substraction, deFlat)
- Cosmetic Correction
- Image Registration
- Image Integration
- Mure Denoise
Then :
- Create super L image (integration of L and RGB individual channel)
- Create RGB image and color balance using R,G,B channels
- LRGB combination with superL
- DBE
- Color balance on stars
- Color Saturation masked (and desaturate bkg)
- Deconvolution masked with 1.8 pixel psf
- Background extraction
- Going NL using HT
- TGV denoise (no mask)
- Local Histogram Equalisation (at 90 pix scale)
- Color Saturation masked using stars to boost stars color
- Color Balance on stars
- Color Saturation masked using stars to boost stars color
- Deflip
- Crop

Final image adjustments performed in Iphoto on Imac :
- levels adjustments

Comments

Revisions

  • sh2-136 "Ghost Nebula" in Cepheus - LRGB, 



    
        

            Daniel.P
    Original
  • Final
    sh2-136 "Ghost Nebula" in Cepheus - LRGB, 



    
        

            Daniel.P
    C

C

Description: with star color deringing

Uploaded: ...

Sky plot

Sky plot

Histogram

sh2-136 "Ghost Nebula" in Cepheus - LRGB, 



    
        

            Daniel.P