Galactic Trio in Leo

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Luminance data with NGC 3628's tidal tail visible in the upper left.

The Leo Triplet is comprised of three spiral galaxies, located in the constellation Leo. This small galaxy group is a springtime favorite in the Northern Hemisphere for both astrophotographers and visual observers due to their brightness and close proximity to each other in the sky.

1. M65 (NGC 3623)
   • Distance: 35 million light years
   • Apparent Magnitude: 9.3
   • Inclination 71 deg
     
     
2. M66 (NGC 3627)
   • Distance: 35 million light years
   • Apparent Magnitude: 8.9
   • Inclination 60 deg
     
     
3. NGC 3628 ("Hamburger Galaxy")
   • Distance: 35 million light years
   • Apparent Magnitude: 9.5
   • Inclination 89 deg

The Leo Triplet is also a favorite target for researchers of galactic dynamics. Studying the Leo Triplet provides insights into how galaxies evolve, interact, and influence each other's evolution over cosmic timescales. The gravitational interactions between these galaxies lead to disturbances in their structures, such as distortions in their shapes, the formation of tidal tails, and birth of new stars within them.

M65 and M66 are close (comparable to the distance from the Milky Way to the Large Magellanic Cloud), although they do not appear to be interacting based on recent research. M66 and NGC 3628 are roughly twice that distance, but are strongly interacting. A 300,000 light year long tidal tail of young, blue star clusters has formed in the wake of NGC 3628 as a result. The interaction has also caused warping of the spiral arms within M66 and has set off an era of vigorous star formation. The blue color that appears within M66 is caused by the birth of new stars which have high surface temperatures. The extreme heat from these stars ionize the surrounding interstellar gas which begins to glow red (H-alpha). See this paper for recent research into the trio’s interactions.

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Leo Triplet

Constellation: Leo

Coordinates: RA: 11h 18m 08.9s Dec: +13° 6’ 48.2”

Dates Acquired: March 7, April 6 & April 8 2024

Moon Illumination (average): 4%

Bortle Class: 6

Latitude: +43°

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Equipment Info:

Telescope: William Optics Grand Tourismo 71 with 6AIII Flattener/Reducer

Focal Length: 335.2mm

f/4.2

Main Camera: ZWO 533MM-Pro

Guide Camera: ZWO 290MM-mini

Mount: Sky Watcher EQ6Ri-Pro

Filters: Astrodon 31mm (LRGB)

Integration:

Lum - 192 x 180s = 9h 36m

Red - 88 x 180s = 4h 24m

Green - 51 x 180s = 2h 33m

Blue - 76 x 180s = 3h 48m

Calibrated with flats & dark flats

Total Light Integration: 20h 21m

Processing Techniques - PixInsight Workflow:

1. WBPP & GraXpert - LRGB

2. RGB - RGBCombination, SPCC

3. L - BlurXTerminator

4. GeneralizedHyperbolicStretch on L and RBG

5. StarXTerminator on L & RGB

   • SCNR-Green , CorrectMagentaStars script, Curves on RGB-Stars

   • Curves on RGB-Starless

   • PixelMath to recombine stars & starless:

     RGBK = combine(stars, starless, op_screen())

6. Apply L to RGB via LRBGCombination

7. Crurves on LRGB

8. NoiseXTerminator

9. Plate solved and annotated in PixInsight

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