NGC 507
Arp 229
Galaxy
Pisces
R.A. 01h23m39.9s
Dec. +33°15'21" (2000)
Magnitude: 12.50 B
Size: 2.5' x 1.7'
Type E-S0
My apologies for the rather random nature of this piece but it was put together during a star party
here in the UK which now almost always means sitting in a damp field for 7 days of total cloud
cover and the telescope rarely coming out of the car and usually little or no internet connection.
The NGC 507 group is the single richest group of galaxies in Pisces containing 9 NGC galaxies
brighter than 15th magnitude. There are also a number of galaxies listed in the IC here as well.
The chart also shows the profusion of fainter background galaxies that are probably not part of
the group.
ngc507cht2.jpg
The group is part of the Perseus-Pisces super cluster and confusingly the NGC 507 group
is also known as the Pisces cluster although this name is more usually attached to the NGC 383
group. See http://adventuresindeepspace.com/supercl.htm for more information on the supercluster.
The largest and brightest galaxy in the group, NGC 507, a lenticular galaxy and the BCG, was
discovered to have faint concentric shells by Halton Arp when looking at plates taken by the
200". He subsequently added it as Arp 299 in his catalogue of peculiar galaxies. These shells
are now thought to be the product of ancient mergers. NGC 507 is also an AGN and seems to
have radio lobes associated with it. Recent radio observations appear to show that there are
ancient lobes from previous outburst from NCG 507 and they are distorted by gas sloshing
around in the cluster. The group was also included in the VV catalogue of interacting galaxies as
VV 207. The majority of the bright galaxies in the group including NGC 507 were discovered by
William Herschel in 1784.
ngc507pan.jpg
NGC 508 is not part of Arp 229 despite some sources suggesting it is. The description by Arp is
quite clear what Arp 229 is. Although they are quite close in angular terms on the sky it is not
clear that NGC 508 is actually physically associated with NGC 507. It is suggested that NGC 499
just to the north may form a double system with NGC 507 and there are two subgroups in the
cluster associated with the two galaxies.
The group does show a number of small sub-structures in its central core which suggests that it
may still be in the process of accreting other smaller groups of galaxies and has not yet reached
its final state. NGC 499 appears to be at the centre of a second peak in the X-Ray halo and may
be the central galaxy of another group merging with the NGC 507 group. Unfortunately, it is not
possible to say which way NGC 499 is moving. The main part of the group is in the form of a chain
but there are a number of galaxies off the side of this chain as well. The group would appear to be
at a distance of 63 Mpc, 230 million light years, and forms part of the main filamentary ridge of the
Perseus-Pisces super cluster that also contains the Abell clusters 262, 347 and 426.
Visually this is a stunning group. The brightest members should be visible in a 22cm telescope but it
is with larger telescopes that the true beauty and number of galaxies in the field is really shown. The
whole group will fit in the medium power field using a modern hyperwide (100 degree AFOV) eyepiece,
but is perhaps best observed with higher power to bring in the fainter galaxies in the group
There is a nice amateur image of the group at https://delsaert.com/wp-content/uplo..._lrgb_crop.jpg.
As always give it a go and let us know what you see
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