Arp’s Peculiar Galaxies
Page 4 of 7
Arp observations 31-40 of 70 total to date.
| Thumbnail | Title/link | Arp Category | Date Observed | Observer Description |
|---|---|---|---|---|
 |
Arp 135 / NGC 1023 | Galaxies with nearby fragments | 2024-03-13 11:09:27 | First observation of the evening starting with Astronomical Dusk. Altitude just under 40° at start. This is a relatively large and bright object that appeared almost immediately in SharpCap. I stayed on it as long as needed to clearly see the bulge at the bottom which is NGC 1023A merging into it; the enhanced version of the image makes this obvious, though increases noise. Note Arp comparison is rotate 180° to match Arp's original image. |
 |
Arp 141 | Material emanating from elliptical galaxies | 2024-03-24 23:22:32 | A clear night, but a full moon. I searched for Arp targets that would be as far from the moon as possible, and this was the first I came up with... The two nucleii came up almost immediately. The bulbous end next. Eventually the loop structure began to fill in. |
 |
Arp 145 / UGC 1840 | Material emanating from elliptical galaxies | 2024-02-29 20:00:01 | Despite an 88% moon, I was determined to capture a number of Arp galaxies in Andromeda, recognizing the window of opportunity this year was short. This was the second observation of the evening, and the target was fairly low in the west. I captured as much data as I could until I judged the thicker atmosphere and glow at the horizon would render further integration useless. SharpCap had some issue subtracting darks, so the full image exhibits what I take to be amp glow from the 294mc-pro camera. Nevertheless, while it won't win "Astrophoto of the Month", it does show Arp 145 clearly, with it's two bright centers and partially merged eliptical galaxies. |
 |
Arp 152 / Virgo A / M87 | Galaxies with jets | 2024-03-13 00:42:00 | As expected for a large Messier object, this is an extremely bright target. The toughest aspect was to set the black level appropriately to show the diffuse outer ring of this nebulous, elliptical galaxy... It's so large, I thought for a while my dark-subtraction in SharpCap was failing, and I was seeing amp glow! However, I was able to identify that the diffusion wasn't quite round, and not "quite" as large as uncontrolled amp-glow with my 294 sensor. This became obvious after about 15m of integration. The S/N ratio was so high, and since there is no structure to speak of in the outer disc, there seemed no advantage to continuing integration longer than the 25m once the two tiny galaxies, LEDA 139919 and UGC 7652, were clear. At first, I thought the dust lane connecting these small galaxies to the galactic center were the "jets" referenced in the Arp Category text. Then a friend pointed out that it's actually a tiny bump on the edge of the galactic core. You can see it if you enlarge the featured image, and an enlarged closeup is in the gallery. It is barely visible in the Arp photograph; note the Arp comparison is rotated 180° relative to the original capture, featured image, and jet enlargement. |
 |
Arp 155 / NGC 3656 | Galaxies disturbed by interior absorption | 2024-03-12 13:38:32 | This was the third Arp observation of the evening. Having switched to Ursa Major, mid evening the target was rising. I judged 53m of integration time was sufficient. |
 |
Arp 158 / NGC 537 | Galaxies disturbed by interior absorption | 2024-02-29 19:39:57 | Another of the targets in Andromeda captured on this night with 88% moon. Time was limited because it was descending towards the horizon; capture started at approximately 40° altitude. Despite moonglow and a relatively dim target, the extensions both above and below were evident in real time and enhanced in Affinity Photo working on SharpCaps "as adjusted" .png file. |
 |
Arp 159 / NGC 4747 | Galaxies disturbed by interior absorption | 2024-06-12 23:52:00 | This is a fascinating and challenging observation. NGC 4747 is a barred spiral galaxy categorized by Arp as exhibiting disturbances due to "interior absorption", though it strikes me that it exhibits several additional forms of disturbance as well. On the image, North is left. The key "internal disturbance" would seem to be an "extra" galactic center to the southeast of the barred center, looking like an additional galactic center extending its line. In addition, a wide tail extends NNE from the main disc of the galaxy, hinting of additional galaxies or dwarf galaxies either invisible within our field of view, or outside of it. A further, extremely faint dust lane extends NE |
 |
Arp 165 / NGC 2418 | Galaxies with diffuse filaments | 2024-03-13 11:51:43 | On an otherwise clear, moonless evening, we experienced a thin layer of high clouds which limited integration time. The "Diffuse Filaments" are not as clear as they would have been had we been able to increase integration time. However, they were just perceptible in SharpCap's live screen in a darkened room where I observe. A very faint arm is evident in the enlarged, contrast-enhanced view applied to the original, SharpCap .png saved "as adjusted". |
 |
Arp 166 / NGC 750-51 | Galaxies with diffuse filaments | 2024-02-21 19:30:17 | Brief observation due to cloud conditions. Despite the very limited integration time, the diffuse filaments connecting NGC 750 and 751 were evident in SharpCap, and even more so after processing in Affinity Photo. This target is close to the minimum resolution of my 8" SCT, though because of the diffuse filaments, very little structure is evident even in the 200" Hale telescope. |
 |
Arp 167 / NGC 2672 | Galaxies with diffuse counter-tails | 2024-03-24 23:43:00 | I selected Arp 167 for this evening because it was a full moon, and Cancer was pretty much the opposite direction, yet reasonably high in the sky. As it turned out, the evening was dark enough and the 55m capture was more than adequate. The two galaxy centers, NGC 2672 (the larger) and 2673 (the smaller) were evident in SharpCap from virtually the first frame. Time was required to capture the diffuse disks which you can see, with sufficient time, are slightly elongated away from the center of mass and the two, bright centers. While it's very tough to say much given the small size of the targets, it does appear to show two galaxies merging, with some detritus left behind along the axis of the merge. |