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Contains:  IC 1805
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Open Cluster Melotte 15 in Cassiopeia - sh2-190 / IC1805 - SHO, 





    
        

            Daniel.P
Open Cluster Melotte 15 in Cassiopeia - sh2-190 / IC1805 - SHO

Open Cluster Melotte 15 in Cassiopeia - sh2-190 / IC1805 - SHO

Acquisition type: Electronically-Assisted Astronomy (EAA)

Technical card

Resolution: 4634x3502

Dates:Sept. 14, 2019

Frames:
AstroDon 5nm Ha filter: 45x600" (gain: 139.00) bin 1x1
AstroDon 5nm OIII filter: 43x600" (gain: 139.00) bin 1x1
AstroDon 5nm SII filter: 39x600" (gain: 139.00) bin 1x1
ZWO new B: 5x120" (gain: 139.00) bin 1x1
ZWO new G: 5x120" (gain: 139.00) bin 1x1
ZWO new R: 5x120" (gain: 139.00) bin 1x1

Integration: 21.7 hours

Darks: ~20

Flats: ~5

Flat darks: ~25

Avg. Moon age: 15.05 days

Avg. Moon phase: 99.91%

Mean SQM: 3.00

Mean FWHM: 19.50

Astrometry.net job: 3003196

RA center: 38.287 degrees

DEC center: 61.449 degrees

Pixel scale: 0.909 arcsec/pixel

Orientation: 0.055 degrees

Field radius: 0.733 degrees

Locations: Duc, Prayssas, Lot et Garonne, France

Data source: Backyard

Description

This image results from exposures spanning over 8 nights : 14, 15, 16, 17, 188, 19, 20 & 22 of september. As the nights were getting longer in september, I let the scope point to this nice area of the sky during the second half of the night.

Despite the nearly full moon shinning, the NB filters did a nice job. However, flats correction was needed to calibrate SHO frames! This is not necessary (with my equipment) on moonless night.

The cooling of the sensor varied at -12C, -15C & -21C, depending on the outside temperature.

The RGB exposures were only used to give a natural color to the stars.

The processing was performed in PI as follows :

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 a super Lum image from S, H & O channels (weights estimated using PI integration on S H O images before noise reduction : 1.0 for Ha, 0.1 for O3 & S2.
- Deconvolution of super Lum masked with 2.3 pixel psf
- Create SHO image using LRGB
- Color balance on nebula and color saturation using mask to protect dark area.
- Create RGB image and color balance and color sat (to be used to color stars in SHO)
- SCNR (G neutral and min)
- Background extraction
- Going NL using HT for SHO & RGB images
- 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)
- Local Histogram Equalisation
- TGV denoise (no mask)

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

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Author

Daniel.P
Daniel.P
License: None (All rights reserved)
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Open Cluster Melotte 15 in Cassiopeia - sh2-190 / IC1805 - SHO, 





    
        

            Daniel.P

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