Galaxies NGC3718 and NGC3729

NGC3718 (centre) is a spiral galaxy with a distinctive twist, found in Ursa Major just south of the Plough. Also designated Arp 214, the mag 10.7 galaxy is 9.2 x 4.4 arcminutes in size. The Arp Atlas of Peculiar Galaxies notes it to be a Seyfert galaxy, meaning it has a very bright active core.

The second-largest galaxy in the image is NGC3729, also a spiral. Both are classed as barred spirals, though the Arp atlas notes that the bar in 3718 is a dust lane rather than being stellar in nature. The two galaxies lie at a similar distance – about 40 million light years – and are probably interacting, which may have caused the distortion in NGC 3718.

To the south (lower left) of NGC3718 is Hickson 56 (Arp 322), a group of 5 galaxies of 15th and 16th magnitude, considerably further away at around 400 million light years.

North is to the upper right in this image.

Exposure times were 9.5 hrs Luminosity, 11 hrs Red, 12 hrs Green and 11 hrs Blue.

Equipment: Planewave CDK-14 corrected Dall-Kirkham scope, FLI Proline P09000 CCD camera and Astrodon E-series filters. Autoguided using a Monster MOAG off-axis guider and Starlight Xpress UltraStar Pro guide camera.

Acquisition software: Maxim DL, ACP Expert Scheduler. Image processing: Pixinsight.