Casitas de Gila, Gila, NM, April 13, 2024

In April, I made my annual Spring trip to New Mexico for galaxy season; so many galaxies, so little time.

Description:

NGC 4449, or Caldwell 21, is an irregular dwarf galaxy located over 10 million light-years from Earth.  In the magenta areas, new stars are being born.  Star formation activity is so widespread and intense, that it is referred to as a starburst galaxy.  While starbursts are typically confined to the central, more densely packed regions of galaxies, star-forming activity in NGC 4449 reaches all the way out to the galaxy’s edge.  These regions may have been spurred by interactions with another galaxy, or perhaps several.  The bluish-white areas are populated by vibrant, young, massive stars.  The Box galaxy stretches less than 20,000 light-years across space. Discovered in 1788 by astronomer William Herschel, Caldwell 21 is part of a group of galaxies found in the constellation Canes Venatici. (NASA)

I was nearing the end of my trip, so NGC 4449 was imaged in one night limiting the Hydrogen-alpha and Luminance data.  However, since the Ha was used only to highlight the emission nebulae in the galaxy, fine detail was not required.

Imaging details:

Celestron 9.25" Edge HD SCT with 0.7x Focal Reducer (FL = 1650mm at f/7)
Celestron Off-axis Guider with ZWO ASI 174 mini guide camera
Losmandy G11 mount with Gemini 2 controller
ZWO ASI 2600MM Pro cooled monochrome camera (-10C)
36mm Chroma filters: 5nm Hydrogen-alpha, Luminance, Red, Green, and Blue

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-alpha    10 min x 8 subframes (80 min), Gain 100, Offset 64, 1x1 binning
Luminance            2 min x 95 subframes (190 min), Gain 100, Offset 64, 1x1 binning
Red                         4 min x 15 subframes (60 min), Gain 100, Offset 64, 1x1 binning
Green                     4 min x 14 subframes (56 min), Gain 100, Offset 64, 1x1 binning
Blue                       4 min x 14 subframes (56 min), Gain 100, Offset 64, 1x1 binning

Total integration time: 7.37 hours