Catalina, AZ, December 20-21, 2023

NGC 1491 (LBN 794 or SH2-206), also called the Fossil Footprint, is an emission nebula located about 9,800 to 12,000 light years away from Earth in the constellation of Perseus.  It was discovered by William Herschel in 1790.  The nebula. is about 21 light years across and contains several very hot, bright, young stars. (Wikipedia)

When I set composition for the nebula and surrounding region, I was unaware of the extent of the “toes” in the footprint, so the image is mis-framed.  An issue with the data was that I only had time to take about two hours of 10 minute exposures for each narrowband filter as the waxing moon was in the way.  Furthermore, I did not have time to take red, green, and blue filter subframes for the stars.  So, this became an experiment in how little data could be used to produce an acceptable result.  This false color image started with the SHO Hubble pallet combination.  The PixInsight SPCC tool was used to calibrate the star colors using the narrowband filter option.  The starless nebula and stars images were combined yielding a decent image that does lack some detail and correct star colors.

Imaging details:

Stellarvue SVX102T refractor with 0.74x focal reducer (FL = 528mm, f/5.2)
ZWO large off-axis guider with a ZWO ASI 174MM mini guide camera
Losmandy G11 mount with Gemini 2
ZWO ASI 2600MM Pro cooled monochrome camera (-10C)
Chroma 36mm Hydrogen-alpha, Oxygen-III, Sulfur-II filters
Equatorial camera rotation: 90 degrees

Software:    Sequence Generator Pro, ASTAP plate solving, PHD2 guiding, 
    Losmandy Gemini ASCOM mount control and web client interface,
    SharpCap Pro for polar alignment with a Polemaster camera,
    PixInsight 1.8.9-2,
    Photoshop 2024

Hydrogen-a 10 min x 14 subframes (140 min), Gain 100, Offset 32, 1x1 binning
Oxygen-III  10 min x 12 subframes (120 min), Gain 100, Offset 32, 1x1 binning
Sulfur-II      10 min x 13 subframes (130 min), Gain 100, Offset 32, 1x1 binning

Total integration time: 6.5 hours