LDN 673

Got back out to the local club dark site this weekend for a (mostly) clear new moon night (clouds rolled in around 3AM). Been meaning to hit this target for some months now but never had the weather to do so. Glad I can mark it off the list now.

 

LDN673 is a dense region of dust located in Aquila. The high cloud density prevents starlight from behind the clouds from passing through. The shape sort of reminds me of a virus of some sort.

 

Some comments: I really need to fix the spacing on my scope. With LRGB images, it is especially apparent that the channels don't line up well at the corners - and the green channel really didn't want to play well with this image. I miss having a flatfield astrograph and the FSQ106 cannot come soon enough. This was also my first time using MureDenoise instead of the usual TGVDenoise/MultiscaleMedianTransform linear noise reduction technique. I am very impressed with Mure's capabilities and will add it to my toolset.

 

- Location: Houston Astronomical Society dark site (Bortle 3/4)

- Total Integration Time: 3.4 Hours

 

Equipment:

- Scope: TS107 w/ 0.79x Reducer

- Imaging Camera: QHY 268M

- Filters: Chroma LRGB (36mm)

- Mount: Skywatcher EQ6-R Pro

- Guidescope: SVBony 50mm Guidescope

- Guide camera: QHY5L-ii mono

- Accessories: ZWO EAF, PocketPowerbox Micro, QHY Polemaster

 

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Software:

- N.I.N.A for image acquisition, platesolving, and framing

- PHD2 for guiding

- PixInsight for processing

 

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Acquisition:

- L: 38 x 3m

- R/G/B: 10 x 3m each

- All images at Gain 56, Offset 25 (Readout mode 1) and 5C sensor temperature

- 20 flats per filter

- Master Bias from Library

- Nights: 9/4/21

 

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Processing:

- BatchPreProcessing for calibration

- SubFrameSelector to weigh Luminance subs

- Blink to toss bad Lum subs

- StarAlignment of all subs to Luminance reference

- ImageIntegration of LRGB sets

 

Luminance Processing:

- DynamicCrop

- MureDenoise

- DynamicBackgroundExtraction

- MaskedStretch with background preview reference, 170 iterations

- HistogramTransformation for further midpoint stretch

 

RGB Processing:

- LinearFit B/G masters to R

- ChannelCombination to combine into color

- DynamicCrop

- DynamicBackgroundExtraction

- MaskedStretch

- CurvesTransformation for further stretch

- StarAlign to Luminance

 

Further Processing

- LRGBCombination to combine RGB and Lum

- CurvesTransformation for saturation, S curve

- Duplicate, Starnet to make star mask

- MorphologicalTransformation on StarMask

- Duplicate image, create 2 previews, apply starmask and CurvesTransformation to bring down green level

- SubstituteWithPreview script to apply only previews back to original image

- Extract Luminance, apply to image, ACDNR for luminance noise reduction

- CurvesTransformation for a/b curve adjustment

- DynamicCrop

- Save & Export

Done