| Designation(s) | Arp 175, IC 3481, IC 3483 |
| Object Type(s) | Galaxy, Galaxy Cluster |
| Relevant Catalog(s) | All (Chron), Arp, IC |
| Arp Category | Galaxies with narrow counter-tails |
| Obs. Lat/Long | 42° 17', 073° 57' |
| Constellation | Virgo |
| Date and Time Observed | 2025-07-15 22:40:00 |
| Instrument | EdgeHD 8" w/f7 reducer-1,422mm FL |
| Camera | Player One Apollo-M Mini |
| Image Details | Up is 86.0 degrees E of N. Transparency: Fair. Seeing: Good. Total integration time was 31m. Exposures 15s@300g - no cut filter. Dithered and recentered in SharpCap. No guiding. |
| Description | At the root of the controversy is whether a tidal connection exists between IC 3481 and 3483. In his observing notes, Arp says the connection goes only "two-thirds of the way". But later images with different telescopes and emulsions made it appear that the connection is complete, and my observation could certainly be interpreted that way (though I wouldn't suggest it's definitive). Most Arp fans thought the connection existed, but then spectroscopic analysis gave 3483 a much lower redshift suggesting it was much closer. Arp argued that redshift measurements were not definitive, and if what you could plainly see was in conflict with theory, believe your eyes. Arp ultimately ultimately developed his theory of "intrinsic redshift" which made him a pariah within the Palomar community... It was one thing to point out peculiar galaxies: it made some Palomar astronomers uncomfortable, but others -- in particular Zwicky -- were strong supporters. However, this disagreement placed Arp in direct opposition to a central principle of Hubble's cosmology -- that redshift was a reliable measure of relative distance due to the expansion of the universe. Arp ultimately lost his observing privileges as a result. |
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