The Flying Bat and Squid Nebulae [OC]

lefty7283@lemmy.world to pics@lemmy.world – 105 points –
3

This target has always been a goal of mine since starting in this hobby. While the Flying Nebula (aka Sh2-129, all the red stuff), the Squid Nebula (aka OU4, the blue stuff) was only discovered in 2011. It's stupidly faint. Because of this, and my horrible light pollution, I had to get a ton of exposure time to bring it out, and ended up getting 110 hours total time on it. This is a combination of images taken through hydrogen-alpha and oxygen-iii filters for the nebulosity, plus RGB filters for true-color stars (the nebulosity is kinda close to true color). I have no clue why the Ha region is called 'the flying bat', but the Oiii structure sure looks like a squid alright.

Captured over a shitload of nights from September to December, 2023. Broadband data from a Bortle 9 zone.

Places where I host my other images:

Flickr | Instagram

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, Sii 5nm

  • Agena 50mm Deluxe Straight-Through Guide Scope

  • ZWO ASI-290mc for guiding

  • Moonlite Autofocuser

Acquisition: 110 hours 15 minutes (Camera at -15°C)

BB exposures at half unity gain (76/15), Ha at unity gain (139/21)

  • Ha - 212x600"

  • Oiii - 428

  • L - 200x120"

  • R - 69x60" 69 71 66

  • G - 71x60"

  • B - 66x60"

  • Darks- 30

  • Flats- 30 per filter

Capture Software:

  • Captured using N.I.N.A. and PHD2 for guiding and dithering.

PixInsight Preprocessing:

  • BatchPreProcessing

  • StarAlignment

  • Blink

  • ImageIntegration per channel

  • DrizzleIntegration (2x, Var β=1.5)

  • Dynamic Crop

  • DynamicBackgroundExtraction

duplicated each image and removed stars via StarXterminator. Ran DBE with a shitload of points to generate background model. model subtracted from original pic using the following PixelMath (math courtesy of /u/jimmythechicken1)

$T * med(model) / model

**Narrowband Linear:

  • Honestly just StarXterminator and EZ soft stretch to bring them nonlinear.

  • Duplicated the Oiii before stretching to be used for advanced narrowband combination:

Oiii advaned narrowband combination:

These steps largely follow the ones in Jimmy/NightPhoton's advanced narrowband combination guide.

  • Combine Oiii with Green broadband channel channel (OGG palette)

  • BackgroundNeutralization

  • ColorCalibration

  • StarXterminator to completely remove stars

  • PixelMath to subtract green continuum spectrum, leaving just Oiii signal

  • HistogramTransformation to stretch nonlinear

  • NoiseXterminator + a little concolution

  • CurvesTransformation to adjust black point/contrast

  • Clone stamp to remove a couple background artifacts

  • image saved as 'NB', to be combined later on in nonlinear processing

RGB Linear:

this is really just to have natural star colors

  • SpectroPhotometricColorCalibration

  • BlurXTerminator

Really loving the star correction with its new AI v4 update

  • HSV Repair

  • StarXterminator to make a stars-only image

  • ArcsinhStretch + Histogram transformation to bring stars nonlinear

Nonlinear processing:

  • Combined stretched Ha and Oiii images into a color image using ForaxX's HOO palette:

R = Ha

G= ((Oiii*Ha)^~(Oiii*Ha))*Ha + ~((Oiii*Ha)^(Oiii*Ha))*Oiii

Oiii

  • Background Neutralization

  • Shitloads of Curve Transformation to adjust lightness, saturation, contrast, hues, etc with various masks

  • LocalHistogramEqualization

  • Added in NB image from earlier per the advanced narrowband guide

    only difference from the pixelmath in the guide is that I added NB to the green and blue channels (0.6 and 0.9, respectively) instead of red

  • HistogramTransformation to adjust the black point

  • More curves

  • MLT for medium scale noise reduction in the squid

  • ColorSaturation to slightly desaturate the red nebulas

  • NoiseXterminator

  • Even more curves

  • Pixelmath to add in the stretched stars only image from earlier

This basically re-linearizes the two images, adds them together, and then stretches them back to before

(Jimmy is a processing wizard when it comes to writing up this independent starless processing stuff)

mtf(.005,

mtf(.995,Stars)+

mtf(.995,Starless))

  • Guess what more curves

  • Another round of NoiseXterminator

  • MLT for some small scale chrominance noise reduction

  • Few more slight ColorSaturation adjustments

  • Resample to 60%

  • Annotation

Wait, what? The Blue looks way more like a bat to me. Don't really see anything in the red.

Amazing job 💯💯💯 Thank you for sharing this