My first mosaic project was the
Heart and Soul Nebula in 2021. Now, I'm happy to return to this favorite region of space with a better scope, better filters, and hopefully some better skill.
I gathered data in with Antlia's two ALP-T dual narrowband filters: Ha/[OIII] and [SII]/Hb, taking all my clear nights in October and most of November. This first mosaic is focused on the Heart Nebula. I'll release another mosaic on the Soul Nebula, and then on the overall 10-panel region.
Here are some general details:
- For each panel, capture 5.5 hours (66 x 5 min) in Ha/[OIII], and 6.5 hours (78 x 5 min) in [SII]/Hb.
- Process in AstroPixelProcessor:
- For each panel, extract and stack Ha, [OIII], Hb, and [SII] separately
- For each narrowband channel, create a mosaic on the lower 3 rows, then upper 3 rows, then combine
- Co-register the four mosaics and save.
- combine RGB:
- [SII]: x2.5, (R,G,B) = (50,5,1), L = 15
- Ha: x1.25 , (R,G,B) = (50,10,1), L = 15
- [OIII] x2.5, (R,G,B) = (1,15,75), L = 0
- Hb: x2.5, (R,G,B) = (1,20,75), L = 0
- Export with 20% bg, 3 sigma, 0% base
- Process in photoshop:
- NoiseXterminator (60,60)
- Topaz (low light, 5,5)
- Unsharp mask (75%,1.5 px)
- Remove stars with StarXterminator
- Play with colors
- Shift hue of reds -15, yellows around -5, cyan around +5, blue around +5
- Play with curves
- Play wit saturation
- Add stars back, fiddle with their sharpness and brightness, etc.
This is saved at 50% resolution and 80% quality to keep the size ~15 MB, and because Photoshop's "export as" seems to limit me below 10000 pixels in each dimension.
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