obrazell
September 9th, 2018, 07:27 PM
NGC 6962
RA 20h47m19.1s
Dec.: +00°19'15"
Mag 13.00 B
Size: 2.7'x 2.0'
This week’s challenge is the group of galaxies around NGC 6962. There are 6 galaxies catalogued in the NGC in this group, however only NGC 6962 and NCG 6964 (both discovered by William Herschel in 1785) have their identifications certain. The others were either discovered by the Rosse team at Birr (probably discovered by Mitchell) or by Bigourdan. The Rosse observations were only communicated to Dreyer by means of a drawing of the field so it was not so easy for him to determine which galaxies they saw. There are also three objects from the IC catalogue in the area (IC 5057, 5058 and 5061, all found by Bigourdan and all stars ☹ It is only when you start to look at some of these richer galaxy fields that you realise quite how confused some of the early observers got if the positions were not recorded very accurately, which was difficult with faint objects. The core of the group is also listed as WBL 666 (I guess we had to get that number sometime 😊). The WBL catalogue lists 7 galaxies in the group and includes the galaxies NGC 6959, 6961, 6962, 6963,6964 and 6967. I have not been able to definitely identify the other galaxy in the group, although it is almost certainly CGCG 374-011 (PGC 65356). If this is the case at 15.8(B) it should be visible in larger telescopes (it will probably be almost a magnitude brighter in V). The field itself though is littered with much fainter galaxies. There are suggestions that the total number of galaxies in the NGC 6962 group may be as high as 28. Most of these will be faint dwarves though. The group is suspected as being relatively old as it has a well defined core-halo structure. NGC 6962 itself is a fine spiral galaxy, although probably only the core will be visible. As expected from the brightness of the core the system is classed as a LINER, a weak form of AGN. In UV images the spiral arms stand out strongly, an indication of the amount of star formation going on in the galaxy. NGC 6962 also hosted a supernova in 2002. Larger instruments under dark skies may be able to tease out the halo and perhaps even the spiral arms of this object. It may also be interacting with NCG 6964, which could explain the enhanced star formation. The rest of the group appears to be a complete mixture of spirals, lenticulars and Ellipticals. The group distance would appear to be about 56Mpc. At this distance NGC 6962 will be a large spiral galaxy, somewhat larger than our own Milky Way. In visual terms it would appear that NGC 6962 and 6964 will be visible in a 14”, but probably not very impressive. NSOG Vol 1 suggests that all the NGC galaxies in the group are within the reach of 16/18” scopes. I suspect this may be the case from the high dark skies of Arizona but from somewhere like the UK it may require more aperture to see the fainter ones. The group is fairly compact and most of the galaxies should be visible together in a high-power field. Although the chart gives one view of the NGC numbers in this field there has been some disagreement about which NGC number is attached to which galaxy so other programs may give different numbering, depending on their view of the historical correction of NGC objects.
3178
3179
As always give it a go and let us know.
RA 20h47m19.1s
Dec.: +00°19'15"
Mag 13.00 B
Size: 2.7'x 2.0'
This week’s challenge is the group of galaxies around NGC 6962. There are 6 galaxies catalogued in the NGC in this group, however only NGC 6962 and NCG 6964 (both discovered by William Herschel in 1785) have their identifications certain. The others were either discovered by the Rosse team at Birr (probably discovered by Mitchell) or by Bigourdan. The Rosse observations were only communicated to Dreyer by means of a drawing of the field so it was not so easy for him to determine which galaxies they saw. There are also three objects from the IC catalogue in the area (IC 5057, 5058 and 5061, all found by Bigourdan and all stars ☹ It is only when you start to look at some of these richer galaxy fields that you realise quite how confused some of the early observers got if the positions were not recorded very accurately, which was difficult with faint objects. The core of the group is also listed as WBL 666 (I guess we had to get that number sometime 😊). The WBL catalogue lists 7 galaxies in the group and includes the galaxies NGC 6959, 6961, 6962, 6963,6964 and 6967. I have not been able to definitely identify the other galaxy in the group, although it is almost certainly CGCG 374-011 (PGC 65356). If this is the case at 15.8(B) it should be visible in larger telescopes (it will probably be almost a magnitude brighter in V). The field itself though is littered with much fainter galaxies. There are suggestions that the total number of galaxies in the NGC 6962 group may be as high as 28. Most of these will be faint dwarves though. The group is suspected as being relatively old as it has a well defined core-halo structure. NGC 6962 itself is a fine spiral galaxy, although probably only the core will be visible. As expected from the brightness of the core the system is classed as a LINER, a weak form of AGN. In UV images the spiral arms stand out strongly, an indication of the amount of star formation going on in the galaxy. NGC 6962 also hosted a supernova in 2002. Larger instruments under dark skies may be able to tease out the halo and perhaps even the spiral arms of this object. It may also be interacting with NCG 6964, which could explain the enhanced star formation. The rest of the group appears to be a complete mixture of spirals, lenticulars and Ellipticals. The group distance would appear to be about 56Mpc. At this distance NGC 6962 will be a large spiral galaxy, somewhat larger than our own Milky Way. In visual terms it would appear that NGC 6962 and 6964 will be visible in a 14”, but probably not very impressive. NSOG Vol 1 suggests that all the NGC galaxies in the group are within the reach of 16/18” scopes. I suspect this may be the case from the high dark skies of Arizona but from somewhere like the UK it may require more aperture to see the fainter ones. The group is fairly compact and most of the galaxies should be visible together in a high-power field. Although the chart gives one view of the NGC numbers in this field there has been some disagreement about which NGC number is attached to which galaxy so other programs may give different numbering, depending on their view of the historical correction of NGC objects.
3178
3179
As always give it a go and let us know.