Galaxy of the Month Archive 2016

In this series of articles we draw your attention to galaxies particularly worthly of an observer's time.

• December 2016 - Galaxy of the Month

  NGC 2487 in Gemini

  This interactive image of the NGC 2487 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We have a close in finder chart and also a wider field finder chart to help you locate these galaxies.

  This month’s challenge is NGC 2487, a barred spiral galaxy in Gemini.

  It was first discovered by Albert Marth in 1864 using William Lassells 48” speculum metal telescope from Malta which would suggest that it may be a target for larger telescopes.

  Fittingly being in the constellation of Gemini it is also part of a pair of galaxies along with NGC 2486, also discovered by Marth. The pair also feature as entry number 90 in Holmberg’s 1937 catalogue of multiple galaxies.

  The NGC 2486 and NGC 2487 are actually part of a small group of 4 galaxies called LGG 152 which also includes the galaxies NGC 2498 and UGC 4099. The group is interesting because all four members appear to be barred spirals, although there is some question over the classification of NGC 2486 and it may be type Sa. The group appears to be at a distance of 70 Mpc, however NED gives some quite discordant distances for the 4 galaxies so I wonder if they truly are a physical group.

  NGC 2487 was home to the type Ia supernova SN1975O and it is also classified as a radio galaxy, although there seems to be no form of AGN associated with it. NGC 2486 is also described as an emission line galaxy so perhaps there is some interaction going on between NGC 2486 and NGC 2487.

  The two main galaxies are discussed in Night Sky Observer's Guide (NSOG) Volume 1 as objects for 16/18” telescopes but are described as faint ovals. In theory with a modern medium power (say 200x) hyperwide field (100 degree) eyepiece all three NGC galaxies should fit in the same field of view, however NGC 2498 may be quite faint and difficult to find. It was originally discovered in 1885 by Stephan (of Stephans quintet fame) using a 31” sliver on glass reflector. Steve Gottlieb reports observations of all three NGC galaxies with a 17.5” reflector, but these would have been from altitude.

  UGC 4099 is quite a distance from the main pair being perhaps 44’ away in a SE direction from NGC 2487.

  For those with large telescopes there is a faint IC galaxy IC 482 forming an equilateral triangle with NGC 2487 and 2498. At 15th magnitude this galaxy will probably require telescopes in the 50cm+ class to find. This galaxy is unrelated to the others being a more distant object.

  Owen Brazell - Galaxy Section Director

• November 2016 - Galaxy of the Month

  Abell 2666 in Pegasus

  This interactive image of the Abell 2666 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies.

  Located just inside the square of Pegasus the galaxy cluster AGC 2666 is often overlooked by observers. It appears in neither the Night Sky Observers Guide (NSOG) or L&S which is perhaps rather surprising. It even does not make the Webb Deep-Sky Society Observer's Handbook (WDSSOH) Vol. 5! Despite this it seems to be quite a common imaging target.

  The main galaxies in the group lie along a line anchored on the giant cD galaxy NGC 7768. At around 12th magnitude NGC 7768 was discovered by John Herschel in 1828, but the other three NGC galaxies in the group are much fainter and were discovered by Lord Rosse and his assistants using the 72” reflector at Birr. These are NGC 7765, 7766 and 7767 and they come in at around 14th magnitude. There are also a number of non NGC galaxies in the chain at around the same magnitude. As such I think this cluster will be a target for larger telescopes.

  With the exception of NGC 7768 the brighter members of the group appear to be disproportionally spiral galaxies. NGC 7768 has a number of interesting properties and as well as having a supermassive black hole at its centre it has far fewer globular clusters than might be expected for a galaxy of its size and location. Hubble did observe the galaxy and the image can be retrieved from the Hubble Legacy Archive but the original is not too interesting. Properly stretched however the centre of the galaxy does show a dust disk, unusual for this type of galaxy.

  

  A number of the galaxies in the cluster show signs of interactions but perhaps the most interesting is the galaxy labelled as MCG 4-56-14 in the accompanying chart. It shows signs of an enormous plume on deep images extending from its spiral arm, not unlike the more famous atoms for peace galaxy NGC 7252. It is almost certainly the remnant of a recent merger. One of the best amateur images can be found on the Rancho Del Sol Observatory website. Even the SDSS image does not show the plume well. MCG 4-56-14 is also a LINER galaxy, an active galaxy with emission lines from an AGN. Note that as always what name a galaxy is given tends to be at the choice of the article writer so MCG 4-56-14 is also referenced as CGCG 477-016 in some articles.

  NED suggests the diameter of the group is of the order of 50 arcmins but the main core is much smaller than that, with the main line perhaps 13 arcmin in length. The group lies at a distance of about 112 Mpc which gives it an Abell distance classification of 1 (where 0 is the closest). There are some very blue objects in the SDSS image which appear to be foreground sdO stars.

  Owen Brazell - Galaxy Section Director

• October 2016 - Galaxy of the Month

  NGC 7046 in Equuleus

  This interactive image of the NGC 7046 was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies.

  Equuleus is not a constellation often thought of in deep sky circles, with good reason as there is really nothing of note in the constellation. It does however boast one reasonably bright galaxy in NGC 7046.

  First discovered by William Herschel in October 1790, NGC 7046 is a barred spiral galaxy with a listed magnitude of 14. The core of the galaxy is probably all that will be seen, except with the largest scopes, of this object. It does have a fainter halo with some structure.

  NGC 7046 is listed as part of a small group of galaxies including IC 1364 and IC 1368. The group is at a distance of perhaps 55 Mpc and appears fairly isolated. There is no evidence of any interactions in the group.

  NSOG suggests 30cm is probably needed to see NGC 7046 and to use a relatively high power in which case more detail than just the core may be seen. L&S suggests 25cm will show it but 30cm is needed to see much detail. Although there are a number of IC objects in the general area of NGC 7046 most were found with a 30” reflector, however two, IC 1365 and IC 1368, were found by the 16-year-old Edward Swift using the 16” refractor that his father Lewis also used. As such these should be visible in larger modern telescopes (say 40cm+) from a good sky.

  IC 1365 is interesting because it is also included in the VV catalogue of interacting galaxies as VV 508. In NED IC 1365 is given as a designation not to one object but to a group of galaxies closely packed together, it was probably the fact that they are so close that it was thought to be an interacting galaxy.

  

  The central galaxy in the group has a classification of cD i.e. a giant amorphous elliptical of a type normally found at the centre of clusters. It appears to have several other galaxies superimposed on its halo. It will be interesting to see if any of the large telescope owners can separate the galaxies. The group appears to be at a distance of about 207 Mpc.

  The other Swift discovery, IC 1368, is actually over the border in Aquarius and quite a distance (40.8’) from NGC 7046. It appears to be quiet a nice edge on spiral galaxy. There are no visual observations I can find for IC 1365 or IC 1368.

  Owen Brazell - Galaxy Section Director

• September 2016 - Galaxy of the Month

  NGC 741 in Pisces

  This interactive image of the NGC 741 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies.

  The galaxy pair NGC 741 and 742 were first discovered by William Herschel in December 1784 using his large 20 foot telescope. They are part of a small group of galaxies listed as WBL 61 which, along with NGC 741 and 742, also contains the galaxies UGC 1425 and 1435 along with a couple of anonymous small galaxies.

  The group does have some nomenclature confusion (as always) in the NGC/IC as a small galaxy close by the main pair is listed as IC 1751 and displayed as such in star charting programs such as Megastar and SkyTools. It is now known that in fact IC 1751 is a duplicate observation of NGC 741 and the galaxy formerly known as IC 1751 should now be called MCG 1-6-6. It is also part of the WBL 61 group.

  The main pair of galaxies appear to be interacting and probably had a collision a few 10’s of million years ago. It is likely that this interaction between NGC 741 and NGC 742 took the form of an almost head on collision.

  

  NGC 741 would also appear to be an inactive AGN as it shows an old faint radio lobe. There appears to be both a radio and an X-Ray filament linking NGC 741 and NGC 742 as well as a hot gas bubble in the group. Both NGC 741 and 742 show point radio sources at their core which suggests the collision was not too disruptive. The results of the collision mirror the optical remnants of the more well-known Taffy Galaxies UGC 12914/12915.

  In terms of group morphology NGC 741, NGC 742 and MCG 1-6-6 are all elliptical galaxies. UGC 1425’s type is unknown but it is probably either an elliptical or lenticular whilst UGC 1435 is probably a spiral galaxy. The interacting pair NGC 741/742 are also known as VV175. NGC 741 is a giant elliptical galaxy that appears to be the centre of a group of approximately 40 galaxies in total. The deep SDSS image shows a lot of faint galaxies in the area.

  Visually NGC 741 should be seen in perhaps 20cm but to see NGC 742 will require probably 30cm and a high power to separate from NGC 741. To get the third member of the triplet MCG 1-6-6 will probably require a telescope in the 40cm class and good skies. The two fainter galaxies may just appear as stellar spots. NGC 741 is also part of the Herschel II list from the AL. I suspect that to pick up the UGC galaxies visually, especially from the UK, will require 50cm aperture or better.

  Owen Brazell - Galaxy Section Director

  A few of our members have provided observations for this field.

• August 2016 - Galaxy of the Month

  NGC 7727 in Aquarius

  This interactive image of the NGC 7727 was provided by the Digitised Sky Survey using Aladin Sky Atlas. You can download a finder chart for this galaxy and another for the wider group.

  NGC 7727, also known as Arp 222, is a face on spiral galaxy in Aquarius.

  First discovered by William Herschel in 1785, the galaxy has numerous star streams and plumes associated with it which are probably the result of a merger with another spiral galaxy about 1 billion years ago. It may take another billion years for this merger to settle down. It was this odd shape that led to its inclusion in Arp’s catalogue of peculiar galaxies. The support for the merger scenario comes from the fact that there are two star like objects near the core of NGC 7727, one of which may be the core of the merging galaxy and the other the main core of NGC 7727.

  NGC 7727 does not seem to have a large reservoir of hydrogen gas to form new stars so it is probably going to become an elliptical galaxy in the future. Images from GALEX, an ultraviolet satellite, show very little star formation going on at the current time in NGC 7727 compared to its neighbour NGC 7724.

  Deep images such as those at Kent Biggs' website, the Sedona Stargazer Observatory gallery and captured by the Chilean Advanced Robotic Telescope 32 inch show the tails and plumes in the galaxy very well. The second link also shows an enhanced version of the core area which shows the dual cores as well.

  NGC 7727’s classification of SAB(s)a pec also gives an idea of its jumbled state. The globular cluster system of NGC 7727 is also strange and it appears to contain 25 young globular star clusters which also support the merger hypothesis. Deep Hubble images show a string of dust clouds, perhaps remnants of spiral arms, in projection across the front of the galaxy. Hubble legacy images can be obtained from their website if you want to do your own processing.

  NGC 7727 is also potentially part of a small group of galaxies listed as LGG 480, which also includes the nearby NGC galaxies 7723 and 7724, along with a couple of MCG galaxies, MCG-2-60-7 and MCG-2-60- 10. The reason I suggest that this group assignment may not be correct is that although NGC 7727 and 7723 are at approximately the same distance of 27 Mpc, NGC 7724 is listed at 37 Mpc in NED. The recession velocities however are fairly close.

  The Night Sky Observer's Guide (NSOG) reports all the galaxies should be visible in a 20-22cm telescope but to see detail you may need 35cm telescope. NGC 7727 is also in the Herschel 400 list from the AL. A medium power field, say 200x centred on NGC 7727 should show NGC 7724 as well using a modern hyperwide eyepiece (100 AFOV). Modern visual observations of the galaxy can also be found on the Deep Sky Observer's Companion – the online database (DOCdb).

  Owen Brazell - Galaxy Section Director

• July 2016 - Galaxy of the Month

  NGC 6906 in Aquila

  This interactive image of the galaxies around NGC 6906 was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We have a widefield finder chart should help you locate these galaxies, and a close-up chart for the image above.

  Summer is never the best time for galaxies but if you do get a clear moonless night in the semi dark then this month’s galaxy is NGC 6906 in Aquila.

  First discovered in 1863 by Albert Marth using William Lassells 48” speculum mirror telescope in Malta this galaxy makes a nice pair with the un-related galaxy NGC 6901 (also discovered by Marth). Interestingly both galaxies are marked as part of a pair in NED but I think this is erroneous.

  NGC 6906 itself is actually part of a sparse group of galaxies as listed in the Lyon Galaxy Group catalogue (LGG). Listed as number 435 in this catalogue the group consists of 3 galaxies, NGC 6906 along with UGC 11551 and UGC 11555. Both of the latter two are actually across the border in the constellation of Delphinius. The group is perhaps 1.6 degrees across on the sky. Interestingly all the galaxies are spirals. The distance is to NGC 6906 is perhaps 60 Mpc, so probably similar to the other two galaxies in the group.

  NGC 6901 is perhaps at a distance of 69 Mpc, so 9 Mpc further away than NGC 6906. NGC 6901 is also incorrectly labelled as IC 5000 due to a bad set of co-ordinates published by Marth and Bigourdan rediscovering it and thinking it was a new galaxy. It is also listed as IC 1316 in SIMBAD but this is now recognised as an error and the designation has been deleted from NED. SIMBAD also lists NGC 6901 as being part of a group of galaxies but I have been unable to determine what other galaxies might be involved. NGC 6906 has also had an IC number assigned to it in IC 5006 but this is really a double star.

  Both NGC 6901 and NGC 6906 are spiral galaxies with NGC 6901 being much further away. There is also a much fainter edge on spiral in the same field but at mag 16 it only has a LEDA number and will probably require a very large telescope to spot visually. NGC 6901 was host to SN 2004da which was discovered by the UK amateur Tom Boles.

  Owen Brazell - Galaxy Section Director

• June 2016 - Galaxy of the Month

  NGC 6702 in Lyra

  This interactive image of the NGC 6702 and NGC 6703 was provided by the Digitised Sky Survey using Aladin Sky Atlas. You can download a finder chart for these galaxies.

  Summer nights in northern climes are not very good for any form of deep sky observing, let alone hunting galaxies and I had debated whether or not to have a GOM for June and July. However just to keep the sequence going for June I decided to add a couple of galaxies in Lyra to the list, NGC 6703 and 6702.

  Although NED suggests that they are a physical pair the fact that the recession velocity for NGC 6702 is 4727 km/s and NCG 6703 has a recession velocity is 2365 km/s suggests that they are not in fact physically associated but may be separated by 30 Mpc.

  Visually they are challenging enough objects that they were not discovered by either of the Herschel’s but had to wait until 1863 when they were found by d’Arrest using an 11” refractor.

  NGC 6702 is classified as an elliptical galaxy (E3) whilst 6703 is a lenticular (S0/E). Images from the DSS show that NGC 6703 appears to have a bright core and then a much fainter halo whilst NGC 6702 appears to be elongated and with a much fainter extension. For owners of larger telescopes there is also an interesting edge on galaxy UGC 11357 close by as well, although this is very much fainter.

  NGC 6702 shows the attributes of a LINER galaxy, one that shows emission lines and probably a sign of a mild AGN or enhanced star formation. NGC 6703 is about 26 Mpc from us whilst NGC 6702 would appear to be nearer 60 Mpc distant. It is possible that NGC 6702 may have undergone a merger on a relatively recent (2 Gyr) timescale from both the colour and the fact it has two distinct globular cluster systems. This would also be borne out by the fact that deep images show a dust lane near the centre of the galaxy.

  NGC 6702 was also the source of a recent supernova 2002cs which was discovered by the amateur astronomer Mark Armstrong and appeared to be a Type Ia, typical for an elliptical galaxy. Both of these galaxies may be seen with a 20cm telescope, although NGC 6702 will be tough to find and will require averted vison at the very least.

  Owen Brazell - Galaxy Section Director

• May 2016 - Galaxy of the Month

  NGC 4111 in Canes Venatici

  This interactive image of the NGC 4111 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies.

  As the summer approaches and dark skies end from northern latitudes I thought I would give the bright galaxy NGC 4111 its turn as the galaxy of the month. Completely independently I found that it had already been chosen as object of the week on the Deep Sky Forum and also as the ESO/Hubble picture of the week, obviously a galaxy whose time has come.

  On the border of Canes Venatici and Ursa Major, NGC 4111 was first discovered by William Herschel in 1788. NGC 4111 is a near edge on lenticular galaxy showing a boxy central core and tapering spiral arms. The galaxy is thought to be at a distance of about 50 million years.

  Deep images from Hubble show a disk of dust and gas orbiting at right angles to the main disk, possibly forming a polar ring galaxy. These are often associated with the mergers of galaxies and this may be all that is left after a merger with a smaller spiral galaxy.

  NGC 4111 itself should be visible in telescopes of 20-22cm in aperture but to see much detail will probably require 40cm. Night Sky Observer's Guide (NSOG) reports that with telescopes of 45cm aperture structure can be seen in the disk.

  NGC 4111 is part of a group of galaxies but there seems to be some disagreement about how many and which galaxies it is associated with. The WBL catalogue lists it as group number 380 consisting of three galaxies NGC 4111, UGC 7094 and a third galaxy, whilst the LGG catalogue lists NGC 4111 as part of a group of 18 galaxies as group 269 but does not include UGC 7094 as part of the group.

  There are also three other NGC galaxies in the immediate area. NGC 4117 was also discovered by William Herschel later in 1788 but the other two are much fainter and were discovered by Stoney in 1851 (NGC 4109) and Mitchell (NGC 4118) in 1854 using Lord Rosse’s 72” reflector at Birr.

  If the NGC galaxies are not enough of a challenge then there are two edge on UGC galaxies UGC 7094 and UGC 7089 in the same field but I think these may require large telescopes in the 20” (50cm) category to see, especially from typical UK skies.

  All the NGC galaxies will fit in the same field of a high power eyepiece as will NGC 4111 and the two UGC galaxies so before we lose the dark skies for the year try and chase down this small group. For double star fans there is also a nice coloured double star HJ 2596 in the same field.

  Owen Brazell - Galaxy Section Director

  Observations of NGC 4111 and the surrounding galaxies: Mike Wood and Andrew Robertson use their large reflectors. It appears that the UGC galaxies do require lots of aperture, but Patrick Maloney suggests that might not be as large as you think.

• April 2016 - Galaxy of the Month

  NGC 3865 and NGC 3866 in Crater

  This interactive image of the NGC 3865 was provided by the Digitised Sky Survey using Aladin Sky Atlas. You can download a finder chart for the area. There's a SkyTools chart for the position of NGC 3854. You're advised to read on to find out why that might be important!

  The constellation of Crater is often ignored from mid-northern latitude because it never rises very high above the murk and is not a distinctive constellation like Corvus. There are however a number of interesting galaxies in this area.

  The galaxy of the month this month is the pairing known as NGC 3865 and 3866. However as always in the NGC if only it was that easy as the pairing are also known as NGC 3854 and 3858 and the literature seems confused as to what designation to use for them. So for instance Megastar and NSOG use NGC 3865 and 3866 as the primary designation whilst SkyTools for instance uses NGC 3854 and 3858.

  The galaxies were originally found visually in 1880 by Andrew Common using a 36” reflector and Dreyer uses the 3865 and 3866 numbers for that discovery. Common’s positions however were not very accurate so they were rediscovered in 1886 by Leavenworth using a 26” refractor. His positions were notoriously bad (at least in RA) so Dreyer added these as new objects in the NGC with the numbers 3854 and 3858.

  The whole sorry story is described by Harold Corwin in his NGC notes (http://haroldcorwin.net/ngcic/) . The problem comes in deciding what NGC number to call the objects because as we have seen they are already mixed up. In theory as Common found them first they should be called by his numbers.

  Interestingly there is some suggestion that this pair is part of a loose group of 18 galaxies, however this comes from a statistical study of galaxies from the 2MASS survey so the reality of this group may be questionable. The group is not listed in any of the other optical galaxy group catalogues.

  NGC 3854 is a barred spiral but does have odd looking spiral arms, perhaps as a result of some form of interaction. It is also very prominent in both the 2MASS near IR images and the GALEX UV images. Hubble images show a very bright core with complex dust clouds.

  NGC 3858 also looks like it may be distorted but the image is complicated by a second bright source near the nucleus which may be a superimposed star or perhaps part of the galaxy. Unfortunately, there are no detailed images of the galaxy to resolve this issue. NGC 3858 is also classified a type 2 Seyfert. It appears to be part of the group with 3854.

  L&S suggest that 3854 (there listed as 3865) is barely visible in 15cm but visible in 30cm. They also suggest that 3866 is just visible in 30cm. Night Sky Observer's Guide (NSOG) suggest both are targets for 40-45cm telescopes and 3866 is tough. These observations will be from much further south than the UK so it will be interesting to see what can be seen from here.

  Owen Brazell - Galaxy Section Director

• March 2016 - Galaxy of the Month

  NGC 2699 Galaxy Group in Hydra

  This interactive image of the NGC 2699 was provided by the Digitised Sky Survey using Aladin Sky Atlas. You can download a finder chart for the area, with another zooming in on the group of galaxies. There's a SkyTools version as well.

  This month’s choice is the group of galaxies surrounding NGC 2699 in Hydra. The Lyon catalogue (LGG) of compact galaxy clusters lists it as number 164 which consists of the galaxies NGC 2695, 2699, 2706 and 2708. Note that NGC 2706 is about 30’ away to the north from the rest of the group.

  There are a bunch of other galaxies in this field in NGC 2697, 2698 and 2709 which although in the same general area do not seem to be associated with the group as defined by the LGG selection, either that or the radial velocities have not been measured well enough.

  To add to the confusion, the UZC-GC catalogue lists the group as number 81 and it suggests the group contains the 7 galaxies NGC 2690, NGC 2695, NGC 2697, 2698, NGC 2699, NGC 2706 and NGC 2709. This is a catalogue based on automated near neighbour search techniques taking into account the recession velocities.

  The brightest two galaxies in the group NGC 2695 and 2708 were discovered by William Herschel in 1785. The rest by a ragtag list of the main NGC observers with varying size telescopes, which suggests the faintness of some of the other members.

  Deep images suggest that NGC 2708 has been undergoing some form of interaction from the tails that appear to be coming off it. This may also be why it is catalogued as an emission line galaxy, although it does not appear to have been an AGN so this maybe from some enhanced star formation.

  The majority of the group appear to be spirals with just 2699 being a confirmed elliptical. The recession velocity would put the group at a distance of around 24 Mpc.

  It is probable that NGC 2708 is the same object that John Herschel found and got added into the NGC as NGC 2727. This is another example of where different charting programs plot objects depending on whether they believe in the historical corrections or not. For more information on the dubious objects in the field see Harold Corwin’s notes on the NGC. There is also some information on these in Wolfgang’s book.

  Given the range of brightness of objects in this field I think it will be a challenge for observers. The brightest two should be visible in 22-30cm telescopes but I suspect the fainter galaxies at around 13th magnitude are going to require scopes of the order of 40cm or above to find, certainly from the kind of typical skies we have in the UK. Finding the fainter galaxies will not be helped by the fact there is a 7th magnitude star in the field.

  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 2016 - Galaxy of the Month

  NGC 2513 Group in Cancer and Canis Minor

  This interactive image of the NGC 2513 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies.

  NGC 2513 on the Cancer/Canis Minor border is the brightest galaxy in a small group. First discovered by William Herschel in 1786 NGC 2513 shines at about 12th magnitude. To its west are two much fainter NGC galaxies first found by Bindon Stoney in 1851 using Lord Rosse’s 72” telescope and catalogued as NGC 2510 and 2511.

  These are all part of a poor galaxy group catalogued as WBL 169. The only other galaxy in the group with a common number is the nearby edge on spiral UGC 04171. The WBL catalogue however lists 9 galaxies in this group but most of the others are not assigned names. They are probably the CGCG galaxies mentioned below. Steve Gottlieb with his 17.5” saw 5 galaxies in the area surrounding NGC 2513.

  The three NGC galaxies appear to be either elliptical galaxies or lenticulars, although NGC 2511 may be a spiral. Two of the others in the group which have assigned types appear to be spirals. The core trio of 2510, 2511 and 2513 was included in Miles Paul’s atlas of galaxy trios (available from the Webb Society) and has in fact featured in DSO 134 in an article on galaxy trios by Al Lamperti.

  

  Detailed kinematic studies of NGC 2513 suggest it may be a triaxial spheroid from the motions of its stars. The group is thought to lie at a distance of about 200 million light years from us. The other galaxies in the group are probably CGCG 59-19, CGCG 59-21 CGCG 59-26, CGCG 59-27 along with UGC 04171.

  As UGC 04171 is an edge on spiral this is likely to be quite difficult to observe so the best candidates outside the NGC galaxies are probably going to be 59-19 and 59-27. Neither of these will be easy and will probably need a large telescope from a very dark site to find.

  The whole group should fit in medium power eyepiece field but the presence of an 8th magnitude star in the same field may make them a little harder to find. I was surprised to find that the group has not made any of the standard references such as the Night Sky Observer's Guide (NSOG). It is likely that an aperture of 40cm or greater will be required to see the main trio and perhaps 50cm+ to see the others, certainly if you are not working from high altitude skies.

  The group is also part of the Astronomical League’s galaxy cluster list so should perhaps be better known than it appears to be.

  Owen Brazell - Galaxy Section Director