Arp’s Peculiar Galaxies
Page 15 of 16
Arp observations 141-150 of 155 total to date.
| Thumbnail | Title/link | Arp Category | Date Observed | Observer Description |
|---|---|---|---|---|
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Arp 304 / NGC 1241 and 1242 | Unclassified double galaxies | 2025-11-22 22:28:00 | Arp 304 consists of two galaxies NGC 1241 and NGC 1242, left to right and a double star to the southeast, NGC 1243. The two galaxies were first seen by William Herschel. John Herschel, unable to see 1242 recorded the double star NGC 1243. Dreyer saw all three but recorded the double star as a nebula. Arp didn't seem too fussed as he left no remarks. The only peculiar structure seems to be a slightly enlarged arm on NGC 1241 pulled away in the direction of NGC 1242. |
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Arp 307 / NGC 2874-2873-2872 | Galaxies with concentric rings or Double Galaxies(?) | 2025-01-26 20:10:00 | This is a lovely cluster, but hard to interpret. Sources don't agree on how Arp categorized it: Kanape and Webb list it as "Double Galaxies" The AL list has the category as having "concentric rings" presumably referring to the lenticular galaxy NGC 2974 alone. The Cal Tech website doesn't list its category. Anyway, judging from the halos around the galaxies, which are most clear in the inverted images (either mine or Arp's) it looks to me that 2974 and 2972 are interacting, and it's ambiguous if 2973 has joined the fun. That said, Arp left a cryptic set of remarks: "Position between pair. Possibly not interacting. " It's ambiguous whether he's referring to 2972 (the medium sized elliptical) or 2973 (the small spiral). |
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Arp 308 / Abell 194 | Unclassified double galaxies | 2025-01-23 19:23:00 | This was a "2 for" - a second Arp galaxy group within the same FOV as "Minkowski's Object" (Arp 133). It consists of two interacting galaxies (L to R): NGC 545, a lenticular galaxy, and NGC 547, an elliptical galaxy. During capture I noticed an extended halo from NGC 545 up and to the right towards Arp 133 (southeast given that N is left in these images), which became more pronounced after processing. Arp, himself, doesn't mention it in comments, saying: "Close ellipticals. Position of central galaxy (NGC 541)". |
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Arp 310 / IC 1259 | Unclassified double galaxies | 2025-08-27 23:58:00 | Arp describes this object as "Very close E galaxies". Famously brief, I'm guessing he's interpreting the 3 nuclei as each belonging to separate galaxies, though I would venture a more common description today might be, "3 merged -- or merging -- galaxies where the nuclei are still distinct". Note Arp remarks further: " Picture is 10X [magnification] of following (No. 311) area". |
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Arp 311 / IC 1258, 1259, 1260 | Unclassified double galaxies | 2025-08-27 23:58:00 | Arp is positively fulsome in his description here: "Same as 310, but shows surrounding field and group. Picture is 4X of preceding (No. 310) area". The two larger galaxies (IC 1258 and 59) certainly do appear to be exchanging mass. The connection to IC 1260 is a little more tenuous but still suggested. |
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Arp 317 / M65 / Leo Triplet | Groups of galaxies | 2025-03-03 21:11:00 | Discovered by Messier (#29) on March 1, 1780 who recorded additional details in the entry for M66. Here he notes only: "Nebula discovered in Leo: It is very faint and contains no star." <--> This is one of my favorite targets, a stunningly beautiful group of three spiral galaxies. There are multiple observations here with different orientations. Tech details are for most recent triplet image, featured. M66 appears to be bent slightly by the attraction to M65. Arp seems to agree with me, as he remarks: "Both galaxies on east show signs of interaction." All three galaxies are quite bright, distinctly visible even after 60 seconds of integration. I have attached a "bonus" image which is a SeeStar 50 capture -- my first of the Triplet -- during a very dark and clear morning. This is the best galaxy capture I've achieved with this $500 automated telescope, and demonstrates what it can achieve when conditions are "perfect". I've also added to the gallery a capture from March of 2025, representing my first ever of M65 stand-alone, outside of the Triplet. Captured with my EdgeHD, 0.7x reducer, and Apollo M-Mini mono camera. |
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Arp 319 / Stephans Quintet / NGC 7320 | Groups of galaxies | 2024-11-03 19:32:00 | Arp 319 depicts a fascinating, compact cluster of 5 galaxies, 4 of which exhibit dramatic distortions -- extended arms, "tails", and a "fan" -- due to gravitational attraction. One imagines the center 4 are approaching a mega merger.... I became aware of Stephan's Quintet originally because of my affection for NGC 7331, its proximity to this group, and the fact that one of the galaxies here is likely gravitationally bound to it. You can see a 2023 capture in the gallery which I found disappointing in the context of this effort. I wasn't aware of the distortions, and didn't try to capture them. I returned on this date to try to do a better one using my monochrome Apollo-M Mini. This is also the first time I "developed" the negative plate found in the Atlas of Peculiar Galaxies for comparison. |
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Arp 320 / Copeland Septet | Groups of galaxies | 2024-02-19 00:00:06 | These 14th magnitude galaxies are tiny and challenging in the best conditions; even more so with an 83% illuminated moon. This was early in our process, and obviously we did not give this enough integration time. I do intend to return to this target at some point, and would look to capture at least an hour with the mono camera, which at F/7 instead of f/10, would be the equivalent of 2-3 hours with the 294mc. That might not fully do it justice, but would be a HUGE improvement over what we see here. We've managed to save ourselves from utter embarrassment by converting the color image to black and white where we could push it harder. |
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Arp 322 / Hickson Compact Group 56 | Chains of galaxies | 2025-05-11 23:59:00 | The first observation following a clear day, but with a full moon. As it turned out clear enough. |
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Arp 324 (Abell 2147) | Chains of galaxies | 2025-07-23 23:55:00 | Arp comments: "Diffuse elongation of E[liptical Galaxy]'s along line joining them." This is pretty evident in both Arp's plate (probably from the POSS survey and taken with the 48" Schmidt telescope rather than the 200" Hale). Interesting that Arp is posting a subset of Abell 2147. George Abell was a Ph.D. student at CalTech who created the Abell catalog as part of his Ph.D. thesis relying on the POSS survey for data. This was Zwicky's big project during this time. The survey was published in 6 volumes just prior to the Atlas of Peculiar Galaxies being published. Abell identified several thousand galaxy clusters within the survey, and his list (expanded later to include the southern hemisphere) is well remembered and a frequent target source for amateur astronomers. |