Arp’s Peculiar Galaxies
Page 11 of 11
Arp observations 101-108 of 108 total to date.
| Thumbnail | Title/link | Arp Category | Date Observed | Observer Description |
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Arp 317 / M65 / Leo Triplet | Groups of galaxies | 2025-03-03 21:11:00 | This is a stunningly beautiful group of three spiral galaxies. There are multiple observations here with different orientations. Tech details are for most recent. 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 had chosen to observe this cluster both because of their brightness, and because they would be rising in the East when an 87% moon would have passed the meridian. Moonglow is responsible for the brown tinge. I have attached a "bonus" image which is a SeeStar 50 capture from a month earlier, 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". |
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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 327 / NGC 1875 / Hickson 34 | Chains of galaxies | 2025-01-02 20:41:00 | This is a tiny, dim group consisting of four galaxies: the brightest is an elliptical galaxy, NGC1875 (13.7m, 0.8'x0.7'). Then, moving up the chain (and the image): PGC1716 (18.3m, 0.2'x0.2'), PGC17175 (17.1m, 0.4'x0.2'), and PGC17173 (17.4m, 0.4x0.2m). The smaller, dimmer galaxies appear to be younger and spiral. Consistent with the close proximity of the four, filaments connecting them are evident. Arp's comment: "Three distorted galaxies in general line toward east." I agree. One imagines that the ultimate outcome will be that all 3 end up absorbed into NGC1875. Imaged on a windy night that required careful use of SharpCap's brightness and FWHM filtering. I was hoping to capture up to an hour of integration, but clouds closed out observing prematurely. |
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Arp 331 / NGC 383 | Chains of galaxies | 2023-12-06 22:00:06 | This is a very rich galaxy-field. Why Arp included it is a little unclear; his remarks are typically cryptic: "Position of NGC 383. Symmetry around large central galaxy. Velocities known." Besides the galaxy cluster that Arp labels, I counted 12 additional galaxies by eye. The Astrometry.net annotation is so cluttered that it's very challenging to read. Included as part of Arp 331 are NGC 383 (central galaxy), 379, 380, 382, 384, 385, 386, and 388. Additional galaxies within the field of view include: NGC 370, 373, 374, 375, 392, 397, 398, 399, 400, 402, 403 plus IC 1614, 1618, 1619. This means the annotation found at least 2 galaxies I didn't count by eye, presumably the IC galaxies (IC 1614 is 17th magnitude). This observation was part of the December 2023 Cloudy Nights EAA Challenge, which is why I observed it when I did. |
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Arp 333 / NGC 1024 | Miscellaneous galaxies | 2024-12-25 23:23:00 | This is an enigmatic cluster of 3 galaxies, showcased by NGC 1024, although Arp included only NGC 1024 in his Atlas. It's classified as miscellaneous/unique for unknown reasons. His remarks state: "Thin circular arms, star in SE superposed on wisp." I wasn't sure that those objects might not be dwarf galaxies, especially because of the superposition, but it turns out that all of the bright shapes with the comparison image are blown-out field stars. NGC 1029 is likely gravitationally bound to 1024, but 1028 is substantially further away as suggested by its smaller size, and confirmed by a much higher red-shift. But, strictly speaking neither is part of Arp 333. |
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Arp 336 / Helix Galaxy | Miscellaneous galaxies | 2022-12-20 20:30:13 | This was captured very early in my EAA career... I'd had less than 30 days of successful captures. Arp was not even a twinkle in my eye. This is a relatively small target which tested the limit of my reduced C9.25 SCT, particularly because I had no idea what I was doing at the time. In particular, I didn't know how to control the SharpCap histogram, so was stacking from raw frames. Luckily I found the old stack, and while there wasn't much I could do with it, I could at least provide a hint of the ring. Anyway, I'm surprised Arp didn't categorize this as a ring galaxy, but here it is. I'll hope to go back later this year to have another go at it. |
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Arp 337 / Cigar Galaxy / M82 | Miscellaneous galaxies | 2024-02-19 20:23:00 | This is another very bright and familiar target, though most of my experience has been wide field captures of the M81 Group. The broad outlines of the galaxy are immediately obvious, but the details of venting and the disruption of the galactic center emerge much more slowly. |