Catalina, AZ, December 13-21, 2023

The Monkey Head Nebula is a region of star birth located 6,400 light-years away in the constellation Orion.  It is designated NGC 2174 and Sharpless Sh2-252.  The nebula is mostly composed of hydrogen gas.  The cloud is sculpted by ultraviolet light carving into the cool hydrogen gas and dust.  As the interstellar dust particles are warmed from the radiation from the stars in the center of the nebula, they heat up and begin to glow.  The prime source of energy in the nebula is the massive, hot star named HD 42088.  This star has a mass 30 times that of the Sun and a surface temperature 6 times greater.  Such stars emit extraordinary amounts of ultraviolet radiation.  The high-energy particles in these stars' outer atmospheres are being blown away in high-speed stellar winds.  There are Oxygen-III and Sulfur-II emissions as well, with the Oxygen light blue forming the Monkey’s face.  In this false color image, the monkey seems to have a wild, red to yellow hairdo.  (NASA Hubblesite)

I began the processing by attempting to create a classic SHO Hubble pallet image.  I linearized the Ha, OIII and SII channels.  The strong SII signal made the color combination difficult to manipulate.  So, I blended the narrowband channels with the Multichannel Synthesis script.  I extracted the luminance to sharpen the details.  RGB stars were processed separately, and the SHO image stars image created with StarXTerminator was used the luminance to create tight LRGB stars.  I then applied the updated Color Mask script to adjust each color region using CurvesTransformation and HistogramTransformation process tools in PixInsight.  I then went back and forth in Photoshop to sharpen, saturate and fine tune the starless false color nebula.

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, Red, Green, and Blue 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 18 subframes (180 min), Gain 100, Offset 32, 1x1 binning
Oxygen-III  10 min x 18 subframes (180 min), Gain 100, Offset 32, 1x1 binning
Sulfur-II      10 min x 18 subframes (180 min), Gain 100, Offset 32, 1x1 binning
Red             1 min x 60 subframes (60 min), Gain 100, Offset 32, 1x1 binning
Green          1 min x 60 subframes (60 min), Gain 100, Offset 32, 1x1 binning
Blue            1 min x 60 subframes (60 min), Gain 100, Offset 32, 1x1 binning

Total integration time: 12 hours