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Technical card

Imaging telescope or lens: APM LZOS 130/780 f/6 LW CNC II 130mm APO

Imaging camera: FLI Microline ML8300

Mount: Takahashi EM-200 Temma2

Guiding telescope or lens: Orion Deluxe 50mm MiniGuider

Guiding camera: Orion SSAG

Focal reducer: William Optics 132/110 FLT Field Flattener

Software: PixInsight 1.8TheSkyXPS CS6

Filter: Astrodon Gen2E LRGB

Resolution: 2500x1900

Astrodon Gen2E Lum: 19x960" -30C bin 1x1
Astrodon Gen2E RGB: 54x240" -30C bin 2x2

Integration: 8.7 hours job: 886193

RA center: 170.248 degrees

DEC center: 13.330 degrees

Pixel scale: 1.839 arcsec/pixel

Orientation: 178.518 degrees

Field radius: 0.802 degrees


The Leo triplet or M66 group is located in the constellation Leo at approximately 35 million light years and contains M66, M65 and NGC 3628. NGC 3628 (Hamburger galaxy) has a 300000 light year long tidal tail that is visible in this image taken mostly at SQM 21.7. The vertically-oriented feature visible at the very end of the tidal tail is a tidal dwarf galaxy (TDG) that was discovered by Nikiel-Wrocynski et al. only last year (2014). The idea of dwarf objects forming from the tidal debris left by galaxy mergers was first proposed by Zwicky in 1956, with many such ‘recycled’ galaxy candidates now known in various merging galaxy systems, with this one the closest to the Milky Way.

Click on the link above the title to compare an inverted crop of this image with that from Leo TDG discovery paper which can be found at:

8.7 hr LRGB
D.A.R.C. Observatory, Mercey Hot Springs, CA 4/12/15, 4/18/15




Sky plot

Sky plot


Leo Triplet with Tidal Tail and Tidal Dwarf Galaxy, jeffweiss9