Object of the Week - June 10, 2018 - Arp 297 (NGC 5754 - group)
Arp 297 = NGC 5752/5753/5754/5755
Bootes
NGC 5754
Ra: 14 45 20
Dec: +38 43 58
Vmag: 13.1
NGC 5752
Vmag: 14.1
NGC 5753
Vmag: 15.0
NGC 5755
Vmag: 13.5
Heard of the Galaxy Group was discovered by William Herschel in 1787. The other NGC companions, the relative faintness indicates that, were discovered nearly 100 years (an observation of NGC 5755 by Herschel was not published) later in 1878 by Lawrence Parsons - the son of the famous "Lord Rosse".
A fifth galaxy, PGC 2135414 (18.2bmag) lies between both pairs and is in reach of larger apertures.
All four galaxies found entry in the Arp Atlas under number 297 (group: "Double galaxies with long filaments"). The question is, why Hickson did not respect and catalogue them. In my mind all Hickson classification terms are complied. So with a missing Hickson number the bright and detailed group is often overlooked.
Both northern (NGC 5753/5755 ~ 450mly ) and both southern (NGC 5754/5752 ~ 210mly) seems to belong together. The long tidal filaments and starburst action confirms the interaction between them. Especially impressive is the long tidal of NGC 5454/5752 (~6') to the west.
In practise the group is interesting in nearly every aperture. While 8-inch to 12-inch telescopes shows the members itself, larger apertures 20-inch+ could show the fainter interaction, especially the arms. I never heard about a visual observation of the very faint long filament to the west, but perhaps Jimi gave or give it a go?
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