Arizona City, Arizona
January 10-30, 2021

A Salvage Operation: Reprocessing in 2023

I imaged Lower’s Nebula in Arizona City, AZ, in 2021.  Every night, the wind was relentless and the seeing was generally below average.  When I first processed the nebula, the result was horrible with bloated stars and little detail.  I did not share or post the Hubble pallet false color image.  In 2023, I started reprocessing older data sets using powerful new tools in PixInsight.  So, I reprocessed SH2-261 narrowband data with my current workflow.  Once again, Russ Croma’s XTerminator tools salvaged a decent rendition from mediocre data.  While SPCC for narrowband data did not result in the correct star colors, it did create a star field that was adequate when combined with a processed starless nebula image.  I ended up creating a classic gold and blue Hubble pallet nebula.  So far, I have not succeeded in creating a more colorful version.  While Lower’s is not a really popular target, it does have some interesting features, especially in the lower portion of the frame.

Sh2-261, Lower's Nebula, is located in the constellation Orion near the border with Gemini.  Sh2-261 is a large, faint region of predominantly ionized hydrogen.  The distance is estimated to be about 3000 light years away (Sky and Telescope, 2019).

Imaging details:

Telescope:    Celestron 9.25" Edge HD SCT
Mount:        Celestron CGEM II mount
Imaging Camera:    ZWO ASI 1600MM Pro cooled monochrome camera (-10C)
Filters:        36mm ZWO Luminance, Red, Green and Blue filters
Accessory:    Celestron 0.7x focal reducer
Guiding:        Celestron off-axis guider with ZWO ASI174MM mini guide camera

Software:    Sequence Generator Pro, PHD2 guiding, Celestron CPWI mount control,
    PixInsight and Photoshop CC 2021

Exposures:

Hydrogen-a    10 min x 27 subframes (270 min), Gain 139, Offset 21, 1x1 binning
Oxygen-III       10 min x 24 subframes (240 min), Gain 139, Offset 21, 1x1 binning
Sulfur-II           10 min x 22 subframes (220 min), Gain 139, Offset 21, 1x1 binning

Total integration time: 12.2 hours