Monday night, the 6th April 2026, clear weather returned to our skies with the waning moon (between full and last quarter) not rising until after midnight. I was looking for something to photograph and settled for the pair of galaxies NGC 3718 and NGC3729 in Ursa Major. They sit just below the bowl of the dipper. Here is what I obtained after 327x15s exposures on the Dwarf 3:-
NGC 3718 is the larger of the two galaxies in the centre of the image. NGC 3729 is its neighbour. I used a gain of 70 in the Dwarf and the astro filter. The final image was processed in Stellar Studio (auto settings) and has been binned x2. The saturation and sharpening have been increased in Photoshop. The first frame was taken at 21:28 BST and the last at 23:20 BST, midpoint 22:24. There is another prominent galaxy that can be seen at the far left of the frame and this is NGC 3756.
A portion of the full frame around the central pair is shown below:-
This shows how NGC 3718 has been distorted by gravitational interaction (possibly with NGC 3729 as they are roughly at a similar distance - 3718 is at 14.7 Mpc and 3729 is at 20.2 Mpc) and the spiral arms have been drawn out into an extended "S" shape. However, note also that there is a dark dust lane running through the centre of the galaxy so we are seeing it edge on with the arms having been drawn out above and below the plane. This galaxy appears in Arp's catalogue of peculiar galaxies as Arp 214. NGC 3729 is a barred spiral galaxy. Strangely enough, just to the right of the tail of stars in NGC 3718 is another group of interacting galaxies and this is Arp 322 or Hickson 56. These galaxies are much farther away at about 130 Mpc.
All text and images © Duncan Hale-Sutton 2026
No comments:
Post a Comment