Celestial hemisphere:  Southern  ·  Constellation: Eridanus (Eri)  ·  Contains:  IC 2118  ·  NGC 1752  ·  The star ψEri  ·  Witch Head nebula
Witch Head Nebula (IC 2118), Andrew Klinger
Witch Head Nebula (IC 2118)
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Witch Head Nebula (IC 2118)

Witch Head Nebula (IC 2118), Andrew Klinger
Witch Head Nebula (IC 2118)
Powered byPixInsight

Witch Head Nebula (IC 2118)

Equipment

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Acquisition details

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Description

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: Atoka, Oklahoma (Bortle 3)

Dates: 11/18/17, 11/21/17, 11/25/17

Gain: 76 Offset: 15

Camera temp: -20C

L: 107x180"

R: 30x180"

G: 32x180"

B: 25x180"

Total integration time: 9hr 42min

64x darks per calibration

30x flats per calibration

200x bias (master bias in library)

Preprocessing:

Batch PreProcessing script to generate calibrated images

StarAlignment to register all frames to a reference L

LocalNormalization per channel

ImageIntegration

DrizzleIntegration

DynamicCrop each master

DBE on each master

RGB processing:

LinearFit to Blue channel

ChannelCombination to combine

PhotometricColorCalibration

SCNR green

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

HistogramTransformation x3

CurvesTransformation w/starmask to saturate stars

CurvesTransformation with only nebula masked to saturate nebulosity

ColorSaturation tool to further saturate nebulosity

Slight HistogramTransformation

SCNR green

L processing:

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

HistogramTransformation

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 function but with a value of F=0.2. (s=starless photo).

LocalHistogramEqualization with inverted starmask

Combined L and RGB with LRGBCombination tool

MorphologicalTransformation for slight star reduction

Resampled to 50% for web posting

Comments

Sky plot

Sky plot

Histogram

Witch Head Nebula (IC 2118), Andrew Klinger