Comet Neowise during its close approach to Earth.

You'll notice two tails. The blue one is the ion tail, caused by the sun's radiation electrically charging the gases. The larger more diffuse tail is the dust tail, where particles are released as the sun vaporizes the comet.

Equipment:

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

74mm aperture stop-down ring (brings scope to f/5.2)

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

Guidescope: Orion 50mm guidescope

Guiding camera: Orion StarShoot Autoguider

Imaging camera: ZWO ASI1600MM-Cool

Accessories:

QHYCCD PoleMaster

Software:

SGP

PHD2

CdC

PixInsight

Acquisition:

Location:

Ft. Griffin State Historic Site, TX

Date: 7/19/2020 (from 10:17-11:09pm)

Gain: 76 Offset: 15

Camera temp: -10C

R: 13x60"

G: 11x60"

B: 12x60"

Total integration time: 36min

64x darks per calibration

30x flats per calibration

200x bias per calibration

Preprocessing:

BatchPreProcessing to calibrate lights

StarAlignment to register lights

To create image for stars:

ImageIntegration on star aligned lights

To create comet-only image:

CometAlignment on star aligned lights

Used ProcessContainer and ImageContainer in conjunction with PixelMath and StarNet to stretch, run StarNet, and finally invert stretch to return to linear.

ImageIntegration of comet aligned starless lights.

Processing on star aligned masters:

DynamicCrop

DynamicBackgroundExtraction

ChannelCombination

BackgroundNeutralization

ColorCalibration

SCNR Green

ArcsinhStretch x2

HistogramTransformation

SCNR Green (making sure there are no green stars on this master)

Processing comet-only masters:

DynamicCrop

TGVDenoise

ChannelCombination

DynamicBackgroundExtraction

BackgroundNeutralization

SCNR Green on background sky

HistogramTransformation

LocalHistogramEqualization

CurvesTransformation

SCNR Green on low signal areas

TGVDenoise targeting background chrominance

LarsonSekanina for contrast enhancements centered on the nucleus

ColorSaturation

CurvesTransformation

Added in stars from the star aligned master using a star mask and PixelMath

MorphologicalTransformation to slightly reduce stars

CurvesTransformation to saturate stars

UnsharpMask to slightly sharpen stars

NoiseGenerator to bring back some fine grain noise to the image.

Resampled 50% for web posting