Hemisphere:  Northern  ·  Constellation: Cassiopeia (Cas)  ·  Contains:  39 chi Cas  ·  PK128-04.1  ·  Sh2-188  ·  The star χCas
Sh2-188 - The Dolphin Nebula, 



    
        

            lefty7283
Powered byPixInsight

Sh2-188 - The Dolphin Nebula

Sh2-188 - The Dolphin Nebula, 



    
        

            lefty7283
Powered byPixInsight

Sh2-188 - The Dolphin Nebula

Technical card

Imaging telescopes or lenses: TPO 6" f/4 Newtonian

Imaging cameras: ZWO ASI1600MM-Pro

Mounts: Orion Sirius EQ-G

Guiding telescopes or lenses: Agena 50mm Deluxe Straight-Through Finder / Guide Scope with Helical Focuser

Guiding cameras: ZWO ASI 120 MC

Software: Nighttime Imaging 'N' Astronomy  ·  PixInsight 1.8 Ripley PixInsight

Filters: Astrodon Ha 31mm 5nm  ·  Astrodon OIII 31mm 3nm

Accessory: ZWO EFW 8 x 1.25″/31mm  ·  Moonlite Model CR Newtonian 2" Format Focuser  ·  SkyWatcher Quattro Coma Corrector


Dates:Sept. 22, 2019Sept. 23, 2019Sept. 25, 2019Sept. 26, 2019

Frames:
Astrodon Ha 31mm 5nm: 69x360" (6h 54') (gain: 139.00) -15C bin 1x1
Astrodon OIII 31mm 3nm: 73x360" (7h 18') (gain: 139.00) -15C bin 1x1

Integration: 14h 12'

Darks: ~30

Flats: ~30

Avg. Moon age: 24.69 days

Avg. Moon phase: 25.95%

Bortle Dark-Sky Scale: 7.00


Astrometry.net job: 2983851

RA center: 1h 30' 33"

DEC center: +58° 25' 8"

Pixel scale: 0.764 arcsec/pixel

Orientation: 84.528 degrees

Field radius: 0.989 degrees


Resolution: 7551x5479

Data source: Backyard

Description

I got inspired by [a recent Astrobin post](https://www.astrobin.com/pa8cu6/) and decided to photograph Sh2-188, although my image isn't nearly as good as the one I saw on AB. This nebula was created by an extremely fast moving star, and the bright part is the bow shock interacting with the interstellar medium. There is also a very diffuse and faint trail of material on the opposite side, but I didn't want to stretch it that much [as it brought out a lot of noise](https://i.imgur.com/gn1DzHw.png). I've also made a [starless version using StarNet++](https://i.imgur.com/Fb1YQcj.jpg) to help show some of the dimmer nebulosity. This is probably the faintest nebula I've shot, [especially when looking at the unprocessed Oiii stack](https://i.imgur.com/RANN8MI.png). Captured on September 22nd, 23rd, 25th, and 26th, 2019 from a bortle 7 zone.



**Equipment:**

* TPO 6" F/4 Imaging Newtonian

* Orion Sirius EQ-G

* ZWO ASI1600MM-Pro

* Skywatcher Quattro Coma Corrector

* ZWO EFW 8x1.25"/31mm

* Astronomik LRGB+CLS Filters- 31mm

* Astrodon 31mm Ha 5nm, Oiii 3nm

* Agena 50mm Deluxe Straight-Through Guide Scope

* ZWO ASI-120MC for guiding

* Moonlite Autofocuser

**Acquisition:** 14 hours 12 minutes (Camera at Unity Gain, -15°C)

* Ha- 69x360"

* Oiii- 73x360"

* Darks- 30

* Flats- 30 per filter

**Capture Software:**

* EQMod mount control. Captured using [N.I.N.A.](https://nighttime-imaging.eu/) and PHD2 for guiding and dithering.

**[PixInsight Processing](https://i.imgur.com/M0QPCvi.png):**

* BatchPreProcessing

* SubframeSelector

* StarAlignment

* [Blink](https://youtu.be/sJeuWZNWImE?t=40)

* ImageIntegration

* DrizzleIntegration (2X, VarK 1.5)

* DynamicCrop

* AutomaticBackgroundExtraction

* DynamicBackgroundExtraction

* TVG/MMT/MLT Noise Reduction

* LinearFit Ha to Oiii



* PixelMath to combine channels

* R= Ha

* G= 0.35 * Ha + 0.65 * Oiii

* B= 0.2 * Ha + 0.8 * Oiii

* AutomaticBackgroundExtraction

* ArcsinhStretch

* HistogramTransformation

* [Curve](https://i.imgur.com/Fyb34PJ.jpg)Transformations

* LRGBCombination with extracted L channel as luminance

* LocalHistogramEqualization

* MLT Noise reduction

* More curves

* MorphologicalTransformation to reduce star sizes

* MMT Noise reduciton

* FastRotation 180 degrees

* Even more curves

* Resample to 85%

* Annotation

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