The Cave Nebula, SH2-155, L(Ha)SHO narrow band composite

[windjammer]

Hi

Here is the Cave Nebula, SH2-155, L(Ha)SHO narrow band. A bad weather July delayed the final filter, but the final exposures eventually came in.  I am pretty pleased with it - OK a bit of oversharpening and false edges in the bright bits, and stars still aren't quite right.  But, for once, the processing was simple, A to B - so I have documented it below for my fellow grasshoppers out there.... Annotated image at the end.

Simon

 

 

Data taken in Astronomik narrowband filters: Ha (656nm), Sii (672nm) and Oiii (501nm). Total exposure time 12.1 hrs.

Ha 1x1 bin - 16x 600s = 2.7hrs, 06-07 July, scope West side, prime focus
Sii 1x1 bin - 22x 600s = 3.7hrs, 07-08 July, scope West side, prime focus
Oiii 1x1 bin - 34x 600s = 5.7 hrs, 06-07 and 09-10 August, scope West side, prime focus

Plate solver:
Resolution ............... 1.247 arcsec/px
Focal distance ........... 750.64 mm
Pixel size ............... 4.54 um
Field of view ............ 56' 31.3" x 43' 31.8"
Image center ............. RA: 22 56 40.959  Dec: +62 38 08.18
Image bounds:
   top-left .............. RA: 22 52 48.395  Dec: +63 01 57.89
   top-right ............. RA: 23 01 04.537  Dec: +62 57 13.95
   bottom-left ........... RA: 22 52 23.052  Dec: +62 18 32.13
   bottom-right .......... RA: 23 00 27.327  Dec: +62 13 55.02

Rig:
Imaging scope: SW Startravel 150mm F5 Refractor, Baader Diamond Track, (2.5x Celestron Luminos 2inch imaging barlow), Atik 460EX mono

Guide scope: SW Evostar 90mm F10, with guiding XY stage, ZWO 120MM camera

Guiding: 2 stage PHD: high frequency guide scope (mount tracking) and low frequency OAG image train guiding (guidescope flex)

Mount: Home made German Equatorial pillow block mount, permanently rooftop mounted.  Spring loaded DEC axis gearing.

Other gadgets: ST4 based anti vibration shutter, ST4 based PEC

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Processing Lights:
PixInsight: Lights, Darks, Flats, Biases: master dark/dark library-> masterbias-> superbias-> calibrated flats-> master flat-> calibrated lights-> cosmetic correction-> aligned lights-> master light-> BXT

PixInsight: Master lights-> crop-> linfit-> final master lights

PixInsight: final master lights->StarNet2 starless-> LRGB Channel Combination (Ha, SHO)-> export xisf starless master.

GradXpert Gradient removal:->import xisf-> GXPT(20pc,3sg)-> export xisf, fits 

Affinity Photo 32 bit image processing:-> import LSHO gxpt starless fits-> reject default stretch-> curves-> paint (cosmetic star halos)-> Topaz Denoise(SN,9,62)-> Topaz Denoise(LL,23,12)-> Selective Colour to Hubble recipe (http://bf-astro.com/hubblep.htm)

Affinity Photo final tart ups:-> Shadows/Highlights live filter-> Topaz Denoise(ST,6,7)-> curves-> brightness/contrast.

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Processing Star Mask:
PixInsight: final master lights-> RGB Channel Combination (SHO)-> export xisf

GradXpert Gradient removal:->import xisf-> GXPT(20pc,3sg)-> export xisf

PixInsight: import SHO gxpt master-> StarNet2 star mask-> export fits starmask

Affinity Photo 32 bit image processing:-> import SHO gxpt starmask fits-> accept default stretch-> Recolour(hue, saturation) live adjustment layer-> Levels live adjustment layer-> Blur Diffuse Glow live filter -> paste Star Mask layer on top of starless final (blend mode 'screen').
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Annotated plate solved image: