Hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  NGC 7023
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The Iris and Ghost Nebula (NGC7023 and vdB 141), 



    
        

            Andrew Klinger
The Iris and Ghost Nebula (NGC7023 and vdB 141)
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The Iris and Ghost Nebula (NGC7023 and vdB 141)

Getting plate-solving status, please wait...
The Iris and Ghost Nebula (NGC7023 and vdB 141), 



    
        

            Andrew Klinger
The Iris and Ghost Nebula (NGC7023 and vdB 141)
Powered byPixInsight

The Iris and Ghost Nebula (NGC7023 and vdB 141)

Equipment

Imaging Telescopes Or Lenses
William Optics GT-81
Imaging Cameras
ZWO ASI1600MM-Cool
Mounts
Orion Sirius EQ-G (HEQ5)
Filters
ZWO B 1.25" · ZWO G 1.25" · ZWO R 1.25" · ZWO L 1.25"
Accessories
PoleMaster · William Optics Flat 6A
Software
Sequence Generator Pro · PHD2 · Cartes du Ciel · EQMOD · PixInsight
Guiding Telescopes Or Lenses
Orion 50 mm Guide Scope
Guiding Cameras
Orion Star Shoot Auto Guider

Acquisition details

Dates:
July 12, 2018
Frames:
ZWO B 1.25": 10x360" (1h) (gain: 76.00) -10°C bin 1x1
ZWO G 1.25": 7x360" (42') (gain: 76.00) -10°C bin 1x1
ZWO L 1.25": 11x360" (1h 6') (gain: 76.00) -10°C bin 1x1
ZWO R 1.25": 16x360" (1h 36') (gain: 76.00) -10°C bin 1x1
Integration:
4h 24'
Darks:
64
Flats:
30
Bias:
200
Avg. Moon age:
28.80 days
Avg. Moon phase:
0.60%
Bortle Dark-Sky Scale:
1.00

Basic astrometry details

Astrometry.net job: 2153483

RA center: 21h07m14s.4

DEC center: +68°2804

Pixel scale: 2.530 arcsec/pixel

Orientation: 179.986 degrees

Field radius: 1.594 degrees

Resolution: 3633x2719

Locations: Chisos Basin, Big Bend National Park, TX, United States

Data source: Traveller

Description

I captured this dusty duo from my stay in Big Bend National Park, TX, a Bortle 1 on the dark sky rating. To take advantage of the dark skies, I chose a target that is all reflection nebula and non-reflective molecular clouds. Cepheus is full of this dust that can only be revealed from dark skies!

With only 4hrs of integration time, I would normally be hesitant to call it “done”, but the dark skies really helped bring the signal through, and some generous noise reduction helped as well. When I return to true dark skies in the future, I’ll most likely continue adding data to this, as it can only get better!

Equipment:

OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)

Mount: Orion Sirius EQ-G (HEQ-5)

Guidescope: Orion 50mm guidescope

Guiding camera: Orion StarShoot Autoguider

Imaging camera: ZWO ASI1600MM-Cool

Software:

SGP

PHD2

CdC

PixInsight

Acquisition:

Location: Chisos Basin, Big Bend National Park, TX (Bortle 1)

Dates: 7/11/18, 7/12/18

Gain: 76 Offset: 15

Camera temp: -10C

L: 11x360"

R: 16x360"

G: 7x360"

B: 10x360"

Total integration time: 4hr 24min

64x darks per calibration

30x flats per calibration

200x bias (master bias in library)

Preprocessing:

Batch PreProcessing script to generate calibrated images

StarAlignment

LocalNormalization

ImageIntegration

DynamicCrop each master

DBE on each master

LinearFit R and B to G

RGB processing:

PhotometricColorCalibration

SCNR green 50%

TGV and MMT noise reduction (via Jon Rista's method)

HistogramTransformation x3

MaskedStretch

SCNR green 100%

CurvesTransformation for saturation

ColorSaturation to further saturate blues and orange dust

CurvesTransformation slight contrast

L processing:

Deconvolution

TGV and MMT noise reduction (via Jon Rista's method)

HistogramTransformation x2 to stretch image

Duplicated the image to create a starless version, using a starmask and several iterations of MMT and MT. Then pushed the faint nebulosity in the starless version using PixelMath expression: "1-(1-$T)*(1-$T)"

Combined the starless version with the image using PixelMath expression "F=0.4; (1-(1-$T)*(1-s)*F)+($T*~F)" followed by the same expression with F=0.2 (s=starless photo).

HistogramTransformation to move blacks in

ExponentialTransformation with a mask showing just the dust to bring it forward a tad more

LocalHistogramEqualization

Combined L and RGB with LRGBCombination tool

CurvesTransformation to neutralize background color

MorphologicalTransformation for slight star reduction

ACDNR final noise reduction

Resampled to 80% for web posting

Comments

Sky plot

Sky plot

Histogram

The Iris and Ghost Nebula (NGC7023 and vdB 141), 



    
        

            Andrew Klinger