Based on a recessional velocity of 4555 km/sec, NGC is about 210 million light years away. Given that and its apparent size of 1.0 by 0.2 arcmin, it is about 60 thousand light years across.

The first IC adds "Position angle of extension 60 to 70 degrees (Armagh, 1891). No change".

The second IC lists a corrected RA (per Howe) of 11 51 23.

An unusual one-armed spiral (hence its use as an example of such a galaxy in the Arp Atlas), presumably due to a collision with or near passage by another galaxy millions of years ago (the most likely candidate being PGC 37772, also known as NGC 4027A). Part of the NGC 4038 Group, whose namesake is one of the even more spectacular Antennae Galaxies. Based on recessional velocity of 1670 km/sec, about 75 million light years away, in good agreement with a redshift-independent distance estimate of 85 million light years. Given that and apparent size of 3.2 by 2.4 arcmin, about 70 thousand light years across.

With NGC 4039, the Antennae Galaxies, so-called because of the 300 thousand light year long tails of gas and stars created by their collision. The two galaxies are undergoing a hundred-million-year long collision, in which individual stars rarely (if ever) collide, because they are almost infinitely small in comparison to their separation, but do get scattered through space, as a result of the other galaxy's gravity changing their original motions. Meanwhile, clouds of gas and dust, which extend over vast distances, slam into each other, are violently compressed, and form millions of young stars, many of which are extremely hot, bright objects which heat and light up the regions in which they form. Over a very long period of time the two galaxies will pass through each other, over and over, until they merge. Based on a recessional velocity of 1640 km/sec, NGC 4038 is about 75 million light years away (and of course, at the same distance as NGC 4039). Given that and its apparent size of 5 by 3 arcmin, it is about 100 thousand light years across. Note: This size is for the main structure of the galaxy, and does not include the extended clouds of stars and gas surrounding the pair.

With NGC 4038, the Antennae Galaxies, so-called because of the 300 thousand light year long tails of gas and stars created by their collision. See the discussion of that galaxy for more details about the collision, and images of the galaxies. Based on a recessional velocity of 1640 km/sec, NGC 4039 is about 75 million light years away (and of course, at the same distance as NGC 4038). Given that and its apparent size of 3 by 2 arcmin, the galaxy is about 65 thousand light years across. Note: This size is for the main structure of the galaxy, and does not include the extended clouds of stars and gas surrounding the pair.

The first IC notes "Not seen by Spitaler".