Galaxy of the Month in Lynx

• ACO 779 in Lynx

  February 2024 - Galaxy of the Month

  This month’s challenge is the galaxy cluster ACO 779 in Lynx. Containing at least 7 galaxies found in the NGC this should be a decent target for medium to large scopes.

  The BCG (Brightest Cluster galaxy) is the giant elliptical galaxy NGC 2832, classified as a cD galaxy, also classified as E2, NGC 2832 itself was discovered by William Herschel in 1785. Most of the rest of the group appear to have been discovered by Stoney using Lord Rosse’s 72” at Birr. The Lord Rosse team found 12 galaxies in this area.

  The group seems to contain mostly spirals and lenticulars with an interacting group from the extended VV catalogue in the centre. The same pair is also known as Arp 315, although this may apply to the three galaxies NGC 2830, NGC 2831 and NGC 2832. The galaxies in Arp 315 do not appear to be interacting.

  ACO 779 is quite a small cluster with maybe 83 members and lies maybe 300 million light-years away. The Abell richness class however is 0 which suggests that there may be only 30 galaxies actually in the group. It covers roughly 50 arcminutes on the sky, although deep observations suggest it is more like 90 arcminutes, and lies roughly 40 arcminutes south of Alpha Lyn so it should not be that hard to find.

  The group also contains a number of blue compact dwarf galaxies which appear to be forming stars at this time. There are some suggestions given its distance and location that ACO 779 may be part of the extended substructure of the Coma galaxy filament. There does appear to be some confusion regarding the NGC numbers in the group. NGC 2832 is certain but the others have been shuffled around a bit over time.

  There is a decent amateur image of the group on Bernhard Hubl's website. I think observing this cluster will be best done with a chart as some of the fainter galaxies may look stellar. There is an interesting drawing available on X (Twitter) was made with a relatively small telescope, although this observers drawings appear to have some question marks about them.

  A chart for the cluster can be found in Alvin Huey’s guide to observing Abell Clusters at which can be downloaded from his website. Steve Gottlieb suggests that NGC 2832 is visible in 13” but the others require a larger telescope, which given he usually observes in the high mountains suggests the group may require 45-50 cm to pick up more than the main galaxy. The Night Sky Observer's Guide (NSOG) Vol.1 suggests that a 20cm may show NGC 2832 and 30-35cm will show one of the others but 40-45cm are needed to show more galaxies in the group. The group is included in the Astronomical League’s groups and galaxy clusters program as well as in the SAC list of galaxy clusters.

  Owen Brazell - Galaxy Section Director

• February 2016 - Galaxy of the Month

  NGC 2340 and WBL 133 in Lynx

  This interactive image of the NGC 2340 was provided by the Digitised Sky Survey using Aladin Sky Atlas. You can download a finder chart for this an the surrounding galaxies too, and there's a SkyTools version as well.

  This month’s galaxy of the month was a toss-up between the Abell cluster AGC 569 and the group of galaxies around NGC 2340. Both of these targets are in the constellation of the Lynx.

  Although AGC 569 is an interesting target I felt that as it contains only one NGC galaxy it was going to be perhaps too much of a challenge, except for very large telescope owners.

  The group around NGC 2340 however contains 9 galaxies that have been listed in either the NGC or IC catalogues. It is also classified in the WBL catalogue of poor galaxy clusters as group number 133 containing 10 galaxies so it maybe of more interest.

  Unfortunately, the group is also a classic case of trying to determine which galaxy is which and even the NGC/IC project members seem to have some disagreement about who discovered which galaxy and what numbers should be assigned to them.

  Perhaps the only certainty is the main galaxy NGC 2340 which was discovered by William Herschel in 1788. He may also have discovered NGC 2332 at the same time but his positions are off. What is certain is that John Herschel found it when he re-observed his father’s objects.

  After this it starts to get confusing. The Birr observers using the 72” re-observed the field and found 9 objects but the observations and even more importantly the field drawings seem to be mislabelled so it is unclear which objects they actually found but it is generally accepted that they found the objects that became IC 458, 459, 461, 463, 464 and 465.

  Later Kobold observed the same region with the 18” refractor at Strasbourg and found another set of galaxies in the same area. He seems to have discovered two new galaxies in IC 460 and 462 and confusingly gave the number IC 457 to the galaxy listed as NGC 2330. Unfortunately, he only published his observations quite a long time after he observed the objects and Bigourdan observing in Paris also observed the same area and reported new objects to Dreyer who tried to sort out the mess but did not get too far.

  The full complex story can be found on Harold Corwin’s site at under the NGC notes section, or at least his version of it.

  The group is interesting as it consists almost entirely of elliptical and lenticular galaxies, although the classifications of some of the galaxies may be uncertain because they are faint and have not been studied in much detail.

  My suspicion is that the NGC galaxies as identified should be visible in medium sized telescopes but the IC galaxies may require larger apertures to see.

  I will be interested in hearing what can be seen.

  Owen Brazell - Galaxy Section Director

  And a few of our members have provided observations for this field.

• January 2014 - Galaxy of the Month

  NGC 2683 in Lynx

  

  Image Credit - ESA/Hubble and NASA. Please click on image for a high resolution version.

  First discovered by William Herschel (who else) in 1788 NGC 2683 was nicknamed the UFO galaxy as its shape looked like the classic UFO saucer from early Sci-Fi movies. It is an edge on spiral galaxy with a boxy middle. Found in the fairly non-descript constellation of Lynx – not called because of any resemblance to the animal but because you would need the eyes of a Lynx to see any of its stars. Due to the angle at which it is seen it is not clear whether or not NGC 2362 is a normal or a barred spiral but many astronomers lean towards the latter designation. Although NGC 2362 is both smaller and less luminous than the Milky Way it does seem to have a very large number of globular clusters with about 300 known. Most of these globular clusters appear similar to those in our own galaxy although appears significantly younger at around 3 billion yeas which suggest a recent star formation (interaction) event. The galaxy also appears to have a low amount of neutral and molecular hydrogen and this leads to a currently low level of star formation. There is a fine close-up view of NGC 2683 taken by Hubble.

  NGC 2683 is relatively close to us at a distance of about 16 million light years. This distance may however be an underestimate as more modern distance suggest it is at around 8 Mpc which would be 24 million light years. The nuclear bulge of NGC 2683 appears yellowish on images and this is due to its light passing through the dust in the spiral arms. NGC 2683 also appears to a boundary object between a LINER and a Seyfert Type 2, both of these are forms of AGN and suggest an active massive black hole at the centre of the galaxy. NGC 2683 lies in front of a large number of faint anonymous galaxies that are much further away. Interestingly NGC 2683 does not appear to be part of a group of galaxies but is a true field galaxy. NGC 2683 is by far the brightest galaxy in Lynx but seems to have been overlooked by many observers. It is part of the Herschel 400 list. NGC 2683 does appear in the WSDSOH Vol 4 and is number 47 in Steven O’Meara’s book of Hidden Treasures. Obviously O’Meara’s observations are done with a 4” telescope but the Webb observations with an 8” suggest that it should easily be visible with that size telescope although to see details a larger telescope will be needed. Walter Scott Houston does say it was easily visible in a 3” telescope.

  Owen Brazell - Galaxy Section Director