Leo Triplet, 



Leo Triplet

Leo Triplet, 



Leo Triplet

Acquisition details

April 16, 2021
ZWO UV-IR: 66×60(1h 6′) (gain: 100.00) -10°C
1h 6′
Avg. Moon age:
3.93 days
Avg. Moon phase:
Bortle Dark-Sky Scale:

Resolution: 2976x2984

File size: 16.2 MB

Locations: Backyard, Roebling, New Jersey, United States

Data source: Backyard


Another favorite of amateur astronomers worldwide, the Leo Triplet is one of the finest galaxy clusters in the night sky. Conspicuous enough that Charles Messier discovered two of the three with his small telescopes. From the top, clockwise, are:

NGC 3628, also known casually as the Hamburger Galaxy, is a magnitude 9.5 spiral that likely owes its peculiar shape to a recent (in astronomical terms) merger with another galaxy. This scenario is supported by discoveries of variable x-ray radiation from within the galaxy, as well as the fact that its stars rotate in the opposite direction of its gas! It also has (not visible here) a tidal tail about 3 times as long as the Milky Way is wide, due to gravitational interaction with the other members of the group.

Messier 65 is a fairly normal looking spiral galaxy, at magnitude 9.3, and is about 80,000ly in diameter. Lying approximately 35,000,000ly away, it was discovered along with M66 by Charles Messier in 1780.

Messier 66 is the brightest of the group, at magnitude 8.9, and its spiral arms are visibly deformed, likely from interaction with NGC 3628. There are other signs of past gravitational interactions as well, such as a highly concentrated center mass, as well as a cloud of hydrogen gas that has apparently been pulled from one of the spiral arms.


-William Optics Zenithstar 73mm FPL-53 doublet APO refractor.

-William Optics Flat73r focal reducer/field flattener.

-SkyWatcher EQ6R-Pro equatorial mount.

-ZWO ASI533MC-Pro color camera with ZWO luminance filter.

-William Optics Uniguide 32mm guide scope.

-ZWO ASI462MC color camera with Antlia 685nm IR-pass filter.

-ZWO ASIair Pro.

Pre-processing/Calibration performed in DeepSkyStacker:

-66 60-second lights (gain 100), calibrated with temperature matched darks, flats, and bias frames (30 each at minus 10 degrees Celsius).

-Debayered with Auto Homogeneity Directed interpolation.

-Stacked with Auto Adaptive Weighted Average algorithm.

-Export to 3-plane FITS.

Post-processing performed in Siril:


-Background Extraction.

-Photometric Color Calibration.

-Arcsinh Transformation.

-Histogram transformation.

-Export to TIFF.

Final image adjustments performed in GIMP:

-Fine tune black level (Levels).

-Fine tune colors (Curves).

-Modify saturation balance (Curves).

-Increase saturation (Color Saturation).

-Increase contrast (Curves)

-Export to PNG.

Shot from my light polluted back yard (Bortle 6-7) under a 15% illuminated waning crescent Moon.



Leo Triplet,