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Contains:  Horsehead nebula, IC 432, IC 434, IC 435, NGC 2023, NGC 2024, The star Alnitak (ζOri), The star σOri
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HaRGB - B33 - Horsehead Nebula

Technical card

Imaging telescopes or lenses: William Optics Gran Turismo 81 APO (2018)  ·  William Optics Camera Angle Rotator

Imaging cameras: ASI1600mm Pro

Mounts: Celestron Advanced VX

Guiding telescopes or lenses: QHYCCD PoleMaster  ·  QHYCCD QHYOAG-S  ·  Celestron StarSense

Guiding cameras: QHYCCD QHY5II-M

Focal reducers: William Optics Flat6A-II (x0.80)

Software: Adobe Photoshop CC 2016  ·  Astro Pixel Processor  ·  Sequence Generator Pro  ·  PixInsight 1.8 Ripley  ·  Adobe Lightroom 2017

Filters: Astrodon 3nm Ha 31mm  ·  Astrodon E Series Gen II Blue 31mm  ·  Astrodon E Series Gen II Red 31mm  ·  Astrodon E Series Gen II Green 31mm

Accessory: PrimaLuceLab Sesto Senso Robotic Focusing Motor  ·  ZWO EFW  ·  Celestron SkySync GPS  ·  Kingdel NC860 (i7-8550U)

Dates:Nov. 16, 2018Dec. 10, 2018

Astrodon 3nm Ha 31mm: 59x180" (gain: 139.00) -20C bin 1x1
Astrodon E Series Gen II Blue 31mm: 31x180" (gain: 74.00) -20C bin 1x1
Astrodon E Series Gen II Green 31mm: 40x180" (gain: 74.00) -20C bin 1x1
Astrodon E Series Gen II Red 31mm: 40x180" (gain: 74.00) -20C bin 1x1

Integration: 8.5 hours

Darks: ~50

Flats: ~50

Bias: ~90

Avg. Moon age: 5.56 days

Avg. Moon phase: 33.95%

Bortle Dark-Sky Scale: 4.50

Mean SQM: 20.18

Temperature: -0.75

Basic astrometry details job: 3248595

RA center: 5h 40' 40"

DEC center: -2° 20' 13"

Pixel scale: 3.140 arcsec/pixel

Orientation: 102.574 degrees

Field radius: 1.029 degrees

Resolution: 1920x1371

Locations: Backyard, Coppell, Texas, United States; TAS Atoka Dark Site, Atoka, Oklahoma, United States

Data source: Traveller


My last attempt on the Horsehead Nebula was one year ago - with my astro-modified Nikon D500 on the SkyWatcher Star Adventurer. Still remember that night at Fort Griffin Historical Site, with so much trouble trying to aim the Nikkor 70-200mm lens, could only track for 60 seconds, cranking up all the way up to ISO 5000. Finally only saw the faint horsehead showing up on the view finder - Pure Joy at that moment.

Here comes the revisit. The H-Alpha data was collected at home and RGB data was from TAS Atoka site this Monday. It was freezing cold (-4C).

Somehow I still feel something is missing. I haven't figure it out yet. The resolving power of the GT-81 is not enough to bring up the most important details. I tried to order an Astrodon Sloan i' filter for this target for the infrared data. The order never delivered. It will happen later, I hope.

Pre-processing of Ha Master

- Calibration / Integration, Astro Pixel Processor
- Dynamic Background Extraction, PixInsight
- Deconvolution, PixInsight
- MultiscaleLinearTransformation (Denoise), PixInsight
- ScreenTransferFunction / HistogramTransformation, PixInsight.

Pre-processing of RGB Masters

- Calibration / Integration, Astro Pixel Processor
- Dynamic Background Extraction, PixInsight
- MultiscaleLinearTransformation (Denoise), PixInsight
- MorphologicalTransformation, PixInsight
- ScreenTransferFunction / HistogramTransformation, PixInsight.

HaRGB Combination & Post-processing

- LRGBCombination (Ha master as the Lum), PixInsight
- Final Touch-up, Photoshop



Min Xie
License: Attribution-NonCommercial Creative Commons

Sky plot

Sky plot


HaRGB - B33 - Horsehead Nebula, 


            Min Xie