Object name: ARP308

Designation(s): ARP308, ARP133, NGC0535, NGC0541, NGC0543, NGC0545, NGC0548, NGC0547, MINKOWSKIS_OBJECT,

Arp 308 is a pair of galaxies; NGC 545 and NGC 547 that is associated with the radio source 3C40. That is NGC 547 is considered to be the source of 3C40. Arp put the pair in his category of simply double galaxies. His simple remark says: \"Close ellipticals.\" which isn\'t very informative. NGC 545 to the north is listed as an SA0 galaxy while NGC 547 is E1 and a bright cluster galaxy. Redshift puts it at 6 million light-years further from us that NGC 545. However, NED gives a D-Sigma distance determination that is the same for both. Likely the difference in radial velocity is due to relative motion rather than distance. The exact same D-Sigma distance is found for NGC 541 (Arp 133) as well. A 1964 paper concludes NGC 545 is not interacting with NGC 547. I find that hard to accept.

Notes about the annotated image.
Objects considered part of Abell 194 are listed by name.

Redshift distance using NED\'s 5 year WMAP assumptions are used. They are expressed in billions of light-years. Differences in cluster member radial velocity are most likely due to relative velocity around the cluster\'s center of mass rather than a true distance indicator. Most, likely lie within a few million light-years of each other. The label is immediately right of the object when possible. Otherwise, a line will connect the object and its label.

XMMU J012535.9-012546 is an X-ray galaxy. It appears to be a very compact dwarf of some sort.

ARK 45: A note at NED says \"Together with NGC 0547 this is the radio source 3C 40.\" I\'m not sure how this was determined, especially since NGC 545 is in the middle yet not considered part of 3C 40 that I found. Also, note its redshift is surprisingly different.

NSCS J012537-011739 is a galaxy cluster at 4.97 billion light-years. It contains 36 members. The diameter isn\'t specified. I see a dozen or two within a few minutes of the center. Many look like faint stars.

WHL J012538.1-011301 is another galaxy cluster at 5.3 billion light-years. It contains only 8 members. Its center is a couple seconds of arc from a faint galaxy, probably the anchoring member. The NED position is only approximate so likely means to point to this galaxy.

The UvES (Ultraviolet Excess Source) is likely a quasar given its distance.

Arp\'s image of these galaxies is made from the same plate and cropped to exclude the other atlas entry. Most of his images are shorter than the one hour exposure on 103a-0 image. The added time is likely due to losses in the \"Polaroid\" filter. He lists the seeing as average 1\" to 1.5\".

NGC 535 and 543 were discovered by Heinrich d\'Arrest on October 31, 1864.
NGC 541 was discovered by Heinrich d\'Arrest on October 30, 1864.
NGC 545 and 547 were discovered by William Herschel on October 1, 1785. It isn\'t in either Herschel 400 observing program.
NGC 548 was discovered by George Searle on November 2, 1867.

Arp\'s image of Arp 308

14\" LX200R @ f/10, L=4x10\' RGB=2x10\'x3, STL-11000XM, Paramount ME