Casitas de Gila, Gila, NM, April 2 - 7, 2024

Description:

M65 (right) and M66 (left) are two of the interacting galaxies in the famous Leo Triplet located in the constellation Leo.  They are about 35 million light-years distant in the Leo Spur, which is a gathering of galaxies between the Local Group and Virgo Cluster.  Charles Messier discovered both M65 and M66 in 1780, but he missed the third member, NGC 3628, the Hamburger Galaxy, due to limitations in telescopes at that time.  In 1848, William Parsons, Earl of Rosse, resolved M65 into a “spiral or annular arrangement.”  He later noticed dark lanes on either side of the nucleus. We can see the galaxy’s dust silhouette, which traces a well-defined spiral pattern with two main arms.  At its center lies a diffuse nucleus and bar embedded in a tiny central bulge.  M66 is a Milky Way-sized barred galaxy with prodigious dust, a displaced core, and grand spiral arms.  One of these arms is “hooked,” thanks to distortions suffered in a gravitational encounter with NGC 3628. (from Astronomy Magazine, S. J. O'Meara, September 8, 2022)

M65 and M66 have long been on my target list.  For galaxy season, I used the 9.25” SCT, so the Leo Triplet could not be captured in a single frame.  Since I had imaged NGC 3628 previously, I went after M65 and M66.  I tried to use NINA V3.0 on the first two nights, but my errors and potential bugs caused many problems in the Advanced Sequencer.  I reverted to Sequence Generator Pro which ran flawlessly for the rest of the trip.  My galaxy processing skills had eroded.  It took several iterations to create a decent HaRGB composite color image.  Combining Hydrogen-alpha with RGB has always been challenging, and I used many different methods and parameter settings to give a hint of emission regions in the arms of the galaxy.  Luminance + Hydrogen-alpha processing required very careful, iterative stretching with the GeneralizedHyperbolicStretch tool, employing masks at different stages to protect the highlights and the background.  To validate my result, I compared this image with others on Astrobin.  I found a very similar image created by Eric Coles, a very well known astrophotographer.

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 13 subframes (130 min), Gain 100, Offset 64, 1x1 binning
Luminance            2 min x 135 subframes (270 min), Gain 100, Offset 64, 1x1 binning
Red                        4 min x 23 subframes (92 min), Gain 100, Offset 64, 1x1 binning
Green                    4 min x 23 subframes (92 min), Gain 100, Offset 64, 1x1 binning
Blue                       4 min x 23 subframes (92 min), Gain 100, Offset 64, 1x1 binning

Total integration time: 11.3 hours