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Contains:  NGC 6207, M 13, Great Cluster in Hercules, NGC 6205
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M13 - Great Globular Cluster in Hercules, 





    
        

            Andrew Klinger
M13 - Great Globular Cluster in Hercules

M13 - Great Globular Cluster in Hercules

Technical card

Resolution: 2301x2301

Dates:April 1, 2019

Frames:
ZWO B 1.25": 23x180" (gain: 76.00) -20C bin 1x1
ZWO G 1.25": 23x180" (gain: 76.00) -20C bin 1x1
ZWO R 1.25": 24x180" (gain: 76.00) -20C bin 1x1

Integration: 3.5 hours

Darks: ~64

Flats: ~30

Bias: ~200

Avg. Moon age: 26.01 days

Avg. Moon phase: 13.39%

Bortle Dark-Sky Scale: 3.00

Astrometry.net job: 2665206

RA center: 250.423 degrees

DEC center: 36.455 degrees

Pixel scale: 1.353 arcsec/pixel

Orientation: 9.649 degrees

Field radius: 0.611 degrees

Data source: Traveller

Description

One of the larger globular star clusters in the sky, M13 is home to over 100,000 stars.

This is a fairly large crop with my system. I shot this target a partial night to test a stop-down ring for my scope. The ring slightly improves some optical issues I've been dealing with on my stars.

Equipment:
OTA: William Optics GT81 w/Flat6A (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

Software:
SGP
PHD2
CdC
PixInsight

Acquisition:
Location: Ft Griffin State Historic Park, TX (Bortle 3)
Dates: 4/1/19
Gain: 76 Offset: 15
Camera temp: -20C
R: 24x180"
G: 23x180"
B: 23x180"
Total integration time: 3hr 30min
64x darks per calibration (master from library)
30x flats per calibration
200x bias per calibration (master from library)

Preprocessing:
Batch PreProcessing script to generate calibrated images
StarAlignment to register all frames to the reference
LocalNormalization of all registered frames
ImageIntegration
DrizzleIntegration
DynamicCrop each master
DBE each master

RGB Processing:
TGV and MMT noise reduction (via Jon Rista's method)
LinearFit to Blue
ChannelCombination
PhotometricColorCalibration
Extracted Luminance channel and set aside for processing
ArcsinhStretch x2
MaskedStretch
SCNR green
CurvesTransformation for saturation
ColorSaturation to target blues

L Processing:
Deconvolution
Arcsinhstretch x2
MaskedStretch

Combined L and RGB with LRGBCombination tool
HistogramTransformation
CurvesTransformation to balance background
SCNR green
Resampled to 75% for web posting

Comments

Author

ak_astro
Andrew Klinger
License: None (All rights reserved)
2365
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M13 - Great Globular Cluster in Hercules, 





    
        

            Andrew Klinger