Observation by Graham Roberts: The Leo Triplet

Uploaded by

Paul Downing, FRAS


Graham Roberts


2020 Apr 01 - 22:00


2020 Jun 16 - 13:30



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Field centre

RA: 11h19m
Dec: +13°19'
Position angle: -14°47'

Field size

1°24' × 1°47'

  • William Optics GT81 + Focal Reducer FL 382mm f4.72
  • ZWO1600MM-Cool mono CMOS sensor

180 sec x 42 L Ha, x37 RGB = 153subs. Total Integration Time 7hr 39min


Redhill, Surrey, UK

Target name

Leo Trio


The Leo Triplet

About this image

Each of the galaxies that make up the Leo Triplet is tilted at different angles relative to the view from Earth, thereby producing a variety of form and perspective in the image (cropped & adjusted to accurate orientation @ top-of-the-page).  In addition, various distortions of the galactic discs and other effects demonstrate that the three galaxies in the M66 Group have all been affected by gravitational interactions with each other.  Seen edge-on, the unbarred spiral galaxy NGC 3628 clearly shows a broad band of dust stretching along its outer edge, thus obscuring young stars within the galaxy’s spiral arms.  NGC 3628 seems to be the most affected by the said intergalactic forces which, moreover, has drawn out a tidal tail from the eastern side of the galaxy spanning some 300,000 light years; unfortunately the aforesaid tail is very faint and does not often appear in images – something for another day and a larger telescope!

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