For the last 3 summers I've shot parts of the Veil Nebula, including the [Eastern Veil](https://www.reddit.com/r/space/comments/clpq54/my_24_hour_long_exposure_of_the_eastern_veil/evwyi0t/?context=1), [Western Veil](https://www.reddit.com/r/astrophotography/comments/ocdv98/the_western_veil_nebula/), and [Pickering's Triangle](https://www.reddit.com/r/astrophotography/comments/i1libq/pickerings_triangle/) regions. This summer I decided to try doing a 6-panel mosaic and getting the entire thing in one image. The entire Veil Nebula is about 3 degrees across in the sky, or ~6x the diameter of the full moon. I definitely wanted to get more exposure time on the mosaic (only ended up with ~90 minutes per filter per panel), but summer clouds limited the amount of time I could sink into this before moving in July. I also fiddled with trying to incorporate my images from the previous years into this mosaic, but there were some harsh SNR boundaries at the edges of the image. Although this pic isn't as 'deep' as the previous ones, I'm glad I've finally managed to get pretty much the entire Veil nebula in one final photo.
This photo was downsampled to 70% of it's original 270 Megapixel resolution, which puts it *just* under Flickr's 200MB upload limit. I also made a [starless version](https://i.imgur.com/kNjRoMe.jpg) which helps show some of the fainter nebulosity in the image. All panels were shot over the course of 6 nights from May-July 2022, from my (former) Bortle 6 driveway.
**Places where I host my other images:**
[Instagram](https://www.instagram.com/leftysastrophotography/) | [Flickr](https://www.flickr.com/people/leftysastrophotography/)
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**[Equipment:](https://i.imgur.com/ejpKkwU.jpg)**
* 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-120mc for guiding
* Moonlite Autofocuser
**Acquisition:** 18 hours 36 minutes (Camera at Unity Gain, -15°C)
* Ha - Roughly 1.5 hours of 360" exposures per panel
* Oiii - Roughly 1.5 hours of 360" exposures per panel
> [Exact exposure breakdown here](https://i.imgur.com/GeP7Rxt.png)
* Darks- 30
* Flats- 30 per filter
**Capture Software:**
* Captured using [N.I.N.A.](https://nighttime-imaging.eu) and PHD2 for guiding and dithering.
**PixInsight Processing:**
* BatchPreProcessing
* SubframeSelector
* StarAlignment
* [Blink](https://youtu.be/sJeuWZNWImE?t=40)
* ImageIntegration
* DrizzleIntegration (2x, Var β=1.5)
**Creating the Mosaic:**
> For whatever reason mosaic by coordinates refuses to work for me despite updating/reinstalling pixinsight, or even downloading the script directly from others.
* DynamicCrop to remove stacking artifacts
* Several rounds of automatic and dynamic background extractions to remove gradients
* LinearFit
* Exported photos as tiff, stitched in Microsoft ICE per filter
* StarAlign stitched Oiii to stitched Ha
**Linear:**
* DynamicCrop
* DynamicBackgroundExtraction
* NoiseXTerminator
**Stretching nonlinear:** (method courtesy of /u/xanthine_oxidase, was pretty useful for last year's Western Veil pic)
* MaskedStretch to 0.1 background
* Starnet++ starmask made, subtracted from 0.3 Gray image and colvolved
* Previous image used as a mask to stretch nebulosity without stretching stars
* Normal HistogramTransformation
**Combining Channels:**
* PixelMath to map Ha, Oiii, Oiii to RGB, respectively
**Nonlinear:**
* LRGBCombination with extracted L as luminance, used for chrominance noise reduction
* [Shitloads of CurveTransformations](https://i.imgur.com/xsvBOQh.png) to adjust lightness, saturation, contrast, hues, etc. with various masks
* NoiseXTerminator
* More Curves
* LRGBCombination again for chrominance NR in the stars only
* EZ star reduction
* NoiseGenerator to add noise into reduced star areas
* Even more curves
* ColorSaturation to better bring out the Oiii regions
* More NoiseX
* Export to photoshop, manually masked and curve adjusted a dark banding artifact between two of the stitched panels
* Resample to 70%
* Annotation
downsampled again by 50% for upload to lightbucket + JPEG compressed
lefty7283
