NGC 5363 in Virgo

June 2023 - Galaxy of the Month

Every year I wonder whether to do a GOM for the months of June and July as it no longer gets astronomically dark here at the latitude of the UK to observe anything except bright globular clusters and every year I try and keep the thread going. This month I have chosen the bright pair of galaxies NGC 5363 and NGC 5364 at the eastern end of Virgo. Perhaps as expected they were both discovered by William Herschel. NGC 5363 was found in 1784 but NGC 5364 had to wait another two years until 1786 for its discovery.

NCG 5363 is part of the NGC 5364 group of galaxies which itself is part of the Virgo III cloud, a chain of perhaps 72 galaxy groups galaxies spread out to the east of the main Virgo group. See An Atlas of The Universe website for more information on the Virgo III cloud.

NGC 5363 is characterised as a lenticular galaxy but it seems to contain a large amount of dust which appears to form a spiral shape along with shells of material which suggests a recent merger event. The nucleus is also an AGN of the LINER type. In contrast NGC 5364 is an almost face on grand design spiral. Hubble captured an image of its inner core. Unfortunately, John Herschel independently found this galaxy so it also sometimes goes under the name NGC 5317.

The NGC 5364 group, also known as LGG 362, contains 7 NGC galaxies in NGC 5348, NGC 5356, NGC 5360, NGC 5364, NGC 5363, NGC 5300 and NGC 5338. The group is spread out over a degree of sky. Most of the rest of the galaxies were also found by William Herschel, although a number were also independently discovered by Bindon Stoney using the 72” at Birr. The group is thought to lie at a distance of about 65 million light-years.

NGC 5363 and NGC 5364 form a non-interacting pair, although they may be in the early stages of a gravitational interaction. Bob Franke's website has a nice image of the pair and Thomas Henne provided a wide field view of the group in Picture of the Month.

NGC 5363 and NGC 5364 make several lists including the Astronomical League’s (AL) H400 list and Stephen O’Meara’s Hidden Treasures list (number 72). O’Meara claims that both of these galaxies are visible in a 4” (10cm) refractor but I am guessing this is from his high mountain site.

NGC 5363 and 5364 are pretty close together and both should fit in the same field of view using a medium power eyepiece. I suspect that only the core of NGC 5364 will be seen except with larger instruments as it is a close to face on spiral. The Night Sky Observer's Guide (NSOG) Vol. 2 suggests that NGC 5363 can be seen with 20-25cm instruments as a stellar core. Larger instruments should bring out more of the halo. NGC 5364 may require 35cm or more to see much and to find the small edge on galaxy NGC 5356 will probably require 40-45cm scopes under anything but the best conditions. I suspect that 45-50cm may be required to find the other edge on galaxy NGC 5360.

As an aside this group is next to ACO 1809 but I suspect that is one for the imagers or EAA people, or those using very large telescopes from high sites.

Interestingly NGC 5363 was also included as the C component of the double star BU 1438, also known as STT 273.

Owen Brazell - Galaxy Section Director