ARP148

Arp 148 is more commonly known as Mayall's Object. It is a pair of colliding galaxies about a half billion light-years away. One galaxy has "just" pierced the heart of another and is bursting out the other side. This is best seen in the rather famous Hubble image of this pair.
http://imgsrc.hubblesite.org/hu/db/images/hs-2008-16-aa-large_web.jpg

The Hubble site covers this guy very nicely. Here is what it has to say about this object.
"Arp 148 is the staggering aftermath of an encounter between two galaxies, resulting in a ring-shaped galaxy and a long-tailed companion. The collision between the two parent galaxies produced a shockwave effect that first drew matter into the center and then caused it to propagate outwards in a ring. The elongated companion perpendicular to the ring suggests that Arp 148 is a unique snapshot of an ongoing collision. Infrared observations reveal a strong obscuration region that appears as a dark dust lane across the nucleus in optical light. Arp 148 is nicknamed Mayall's object and is located in the constellation of Ursa Major, the Great Bear, approximately 500 million light-years away. This interacting pair of galaxies is included in Arp's catalog of peculiar galaxies as number 148."

Arp's photo of it with the 200" Palomar scope shows no more than mine, maybe less. At least this time seeing was just barely good enough for me to use 0.5" per pixel when taking my image.
http://ned.ipac.caltech.edu/level5/Arp/Figures/arp148.gif

If you look closely you'll find a great many of the faint "stars" in my image are really distant anonymous galaxies.

14" LX 200R @ f/10, L=9x10'x1 RGB=3x10x2, STL-11000XM, Paramount ME

Related Designations for ARP148

ARP149

Arp 149, IC 803, is a pair of interacting galaxies in Coma Berenices about 370 million light-years away. Arp put it in his category: Galaxies with Jets. He made no comment on this one. I'm not sure what he is seeing as the jet. Is it the very faint plume to the northwest coming from the eastern (left) galaxy or is it the much brighter plume from the western one to the southwest? I have no idea. The galaxy on the right is PGC 215304 and the one to the left is PGC 42367. The pair was discovered by Stephane Javelle on April 25, 1892.

This was taken a night of very good seeing that didn't last. I need at least 100 minutes of L data (160 or more would be better) when imaging at 0.5" per pixel. But seeing went south and I was able to use only 80 minutes of data and preserve the resolution I was getting. In fact, the image is slightly undersampled on the 7 usable frames I obtained! That only happened once before. Galaxies down to 23rd magnitude are seen on the processed image. Not bad for such noisy data.

There are a ton of great galaxies in this image, in fact, the vast majority of the "stars" in this image (except the blue ones) are actually galaxies. If it isn't perfectly round or quite bright then it's likely a galaxy. I could identify nearly 1000 on this 0.0516 square degree field. Unfortunately, this is another field that NED has entered SDSS data for but that data seems to contain no redshift data. So, again, I didn't bother an annotated image as all it would contain is the coordinates of the galaxy which is how Sloan images are cataloged.

Not only didn't Arp have any comment on this pair, I found virtually nothing on it.

The asteroid above the bright star near the top of the image right of center is (32122) 2000 LD10 at magnitude 19.2. About 3 minutes further west and a tad south is the much shorter and fainter trail of 2010 EW38 at magnitude 20.1.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp149.jpeg

14" LX200R @ f/10, L=8x10'x1 RGB=2x10x2', STL-11000XM, Paramount ME

Related Designations for ARP149

ARP150

Arp 150 is part of the 4 galaxy group known as Hickson Compact Group 95 and is located about 500 million light-years away. Unfortunately, I was hit by clouds and only got one third the data I had wanted. I planned on getting the rest but forgot to put it on my list. I didn't realize I'd not gotten the data until too late. It didn't help that I had imaged the first night at 0.5" per pixel and never had a night after that, that was up to the needed seeing quality until I forgot about it. So the image below is very thin and noisy. Color data was very poor. It will have to do for now. I found this text comment about the group but the image it refers to was missing. I believe a is the top galaxy, c the middle one with b the lower left and d lower right. The suspected elliptical is very orange in color in my lousy color data as a distant elliptical "should" be. I could find nothing on it, however, not even a catalog name. While the curving arc is easily seen in my image I didn't get enough data to show the jet very well. It is the linear feature coming out of the "middle" spiral to a point just right of the core of the top elliptical. It shows better in Arp's photo.
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp150.jpeg

In comparing the two I'm mystified by a faded object in my image. His photo shows a star-like object in the arc right above (in Arp's image -- left in mine) the big elliptical galaxy. While it appears to be bright enough to see clearly in my image it only shows very faintly. I don't know why. It also is seen well in the POSS II red and blue images. Apparently, I was hit by clouds even harder than I thought. Someday I'll redo this one.

The other two galaxies in the group are MCG +01-59-046 Sc spiral (right) and MCG +01-59-048 Scd spiral (left). Both are at about the same half billion light years as Arp 150.

Other galaxies in the image are anonymous as far as I can determine.

My thin data image is displayed at 0.5" per pixel rather than my normal 1".

14" LX200R @ f/10, L=4x10x1 RGB=2x10x3, STL-11000XM, Paramount ME

Related Designations for ARP150

ARP151

Arp 151 is a rather odd object. It appears to be a compact galaxy with a long jet (40") that has a bright knot in the middle of it. Or maybe it is a chain of three galaxies as the Vorontso-Velyaminov Interacting Galaxy Catalog indicates saying it is VV144a, b, and c. But http://i273.photobucket.com/albums/jj229/Astronomerica/SDSS-48/NGC5820-SDSS.jpg gives the exact same coordinates for each entry! All point to the lower compact object. Arp put it in his class Galaxies (not classifiable as E or S): with jets. He said nothing about it, however. It appears in many catalogs as many different types of objects. NED says it is a Seyfert 1 galaxy. It's in the 2MASS survey as an infrared object. The Markarian catalog lists it as an ultraviolet excess galaxy. It is in the Second Byurakan Survey of Emission Line Objects as an emission line source. The SDSS lists it as a quasar. That one surprised me greatly. The Luyten Blue Star Catalogue lists it as a blue star! It is in several X-ray catalogs as an X-ray source and some catalogs actually consider it a galaxy. Talk about an identity crisis! A note at NED says this galaxy was the first Luyten blue "star" recognized to be a galaxy. I assume this refers to the blue knot in its center. NED gives its length as 29.4" while I measure it at 53", nearly twice as long. Why such a large difference?

Its redshift distance is about 300 million light-years. NED classes it as an S0 peculiar Seyfert 1 galaxy. If it is a quasar it must be the closest one as I can't recall any less than a billion light-years away, maybe nearly 2 billion. It is located in Ursa Major, about a quarter of the way from M97 to M109.

The SDSS lists the knot a bit less than halfway along the "jet" as a separate galaxy SDSS J112535.23+542314.3/ASK 236801.0 and not part of a galaxy. They show a redshift distance only 4 million light-years closer than Arp 151. So is it a knot or a separate galaxy? Is Arp 151 eating it for lunch and the "jet" a resulting tidal plume of stars possibly drawn away from the galaxy with only the core remaining to appear like a knot that by coincidence of perspective seems to lie on the "jet"? Looking closely there appears to be another knot at the northwestern end of the Jet. It is far fainter than the one near the middle. It carries the designation 2MFGC 08934 and is an IR source as 2MASX J11253416+5423312. What exactly constitutes the flat galaxy in the image I don't know. Lack of redshift data means it could be a background object. Or is it a three galaxy chain as some papers indicate? Also, I seem to see a faint hint of a "jet" or plume going to the southeast of the main condensation as well.

The obvious round "bubble" centered on a point halfway between the blue knot and the northwest end of the "jet" caught me by surprise. I only see hints of it in Arp's image. Slightly stronger hints are seen in the POSS 2 plates. I was about ready to put down to some sort of reflection from the star to the north when I saw it clearly in the SDSS image. It is real but not mentioned in the few papers I looked at on this galaxy. Is it part of the galaxy, an unknown planetary nebula seen in front of the galaxy or something else? I find nothing on it. The color is wrong for a planetary so I'll go with part of the galaxy for now.

This has to be one complex object that is not getting much study. Is there a fourth galaxy involved here? Just to the west of the northern end of Arp 151, and well shown in Arp's image is a small, 20th magnitude, galaxy, SDSS J112531.90+542321.8. With no redshift data, its distance is unknown.

My processing of this one was severely hurt by the halos from the 8th magnitude F0 star just to the north. This was the image that finally got me to start saving for new filters that didn't have this halo problem as the Astrodon Generation 1 filters that came with the camera (used) when I bought it over 5 years ago do. I didn't get them until months later, unfortunately. Anyway, that star cast a lot of noise about this area creating a processing nightmare. The galaxy to the west, ASK 236801.0 appears to have some tidal plumes about it. But those may be noise from the glare of the star as it has a redshift distance of nearly 1 billion light-years and thus not involved with Arp 151 in any way. Though the SDSS image does seem to show some fuzz to the eastern side of it. They too were bothered by halos from the star, just not as severe as mine.

There appear to be two galaxy groups in the image, one with a distance of a bit over 900 million light-years is centered near the left edge of the image. Its coordinates match that of a galaxy. I've marked them at ASK 237033.0 indicating the distance to the galaxy and cluster respectively. The galaxy is also in the 2MASX catalog as a microwave source. The cluster is SDSS-C4-DR3 3275. NED lists it as having 12 members but gives no size. I see 13 in my image alone at about this distance. With the center of the cluster near the left edge, I'd expect a lot more east of my image. There are three more galaxies in the image at 640 million light-years, also along the left edge. They must be in some group as well. Again I didn't go searching farther east than my image to try and find it.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp151.jpeg

14"LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP151

ARP152

Arp 152 is one of the most famous Arp galaxies and often in the news. Here's a link to such a current news item. http://www.universetoday.com/2009/07/02/messier-87-shows-off-for-hundreds-of-earth-bound-astronomers/ It has one of the universe's largest fireworks going off in its core, powered by a giant black hole. This creates a jet. It is the jet that put it in Arp's catalog of course. While we only think of M87 when galactic jets are mentioned Arp has 4 of them in his catalog. Two were well placed this spring and I hoped to image them along with M87 but thanks to the perpetual clouds this didn't happen. I've attached 2 different processing version of this one image; one processed normally except the core has been reduced to show the jet, the other a closeup 2x enlargement of the core and jet region processed just for the jet.
I've also included an annotated image.

M87 is one of the anchor galaxies of the Virgo cluster. Its mass along with that of a couple other supermassive elliptical galaxies seem to define the center of this cluster. One of these M49 is involved with Arp 134. I've reduced the brightness of M87 considerably to allow the jet to be seen. Many of the star-like points around and within the galaxy that make it appear to be in a faint star cluster are really some of its many globular star clusters. There were just too many to try and include them in the annotated image. But virtually all fuzzy stars around and in it are listed at NED as star clusters. Unfortunately, they list both open and globular clusters the same. I think it safe to assume these are all globular clusters.

M 87 was discovered by Johann Koehler on May 5, 1779. Messier didn't hear of the discovery and found it himself on March 18, 1781.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp152.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for ARP152

ARP155

I started a run on ARP 155, also known as NGC 3656 and went to bed. When I got up I found the temperature had dropped nearly 20C during the exposure. This was a major test of my temperature compensating focuser which constantly readjusts the focus based on the temperature every few minutes. I figured thermal lag in the scope would have it ahead of the curve but it was right on. The only problem is my image scale changes and the final image was a good 40 pixels bigger than when it started. So simply stacking them didn't work. I had to resize every frame to compensate. What a pain. There is software to do this but it is expensive (I since got it anyway). A bit more than I wanted to spend at the time this was taken. Also as the image size changes so does the vignetting meaning the flats for the start were right but those for the end didn't begin to compensate for the vignetting correctly. I had to use pseudo flats to compensate. That meant I couldn't dig down into the noise level like I would have liked. But it is my first image under perfectly clear skies in 7 months so I can't complain too much.

In any case, the image did turn out quite well after all day of trying to compensate for the temperature problems. Still since seeing wasn't very good I should retake this one but in over 8 years that hasn't happened.

This galaxy is about 135-140 million light-years away based on the redshift data I found. I located three papers I could read online without paying for them and all three came to very different conclusions about this galaxy. One said it was just an irregular galaxy. That is hard to swallow. Another said it was the product of a near collision of two galaxies but didn't specify what types. They seemed to indicate the result was an elliptical irregular galaxy. The third said it was the collision of two disk galaxies (spirals). To me, it appears like a spiral and an elliptical collided. Though that blue ring that lines up with the dust lane is hard to explain by any standard theory. So is a dust lane that looks like two dark wedges. While it may appear the part of the ring to the left is closest to us and the part to the right then goes behind the core of the galaxy I think the opposite is true. That would make the dark lane actually dust in that ring while the left part clear of the core would be the part farthest from us. Very unsymmetrical either way but the first makes more sense to me. Also possible is that the ring is entirely in front of the other galaxy. Figure it all out and your Ph.D. is waiting. Arp put it in his class for galaxies (not classifiable as S or E) that are disturbed with interior absorption.

Adding to the interest are the reddish star-like objects around it. Those are not stars but dwarf galaxies orbiting it. Farther out are three spiral galaxies that are quite red. This is odd. Spiral galaxies like they are should be reddish in the core but then blue in the arms unless star formation has ceased some time ago. This is seen in the spiral galaxies toward the edge of the frame. Makes me wonder if the red color of the dwarfs and these three spirals isn't due to dust thrown out of the colliding galaxies into deep space around them. Not having access to spectral data on these galaxies I can't tell but it seems possible. Oops. Since this was written distance data on some of these became available and is shown on my annotated image. These aren't dwarf around Arp 155 as papers I saw indicated but distant galaxies reddened by their several billion light-years distance.

Note the spiral at the bottom below NGC 3656. That's PGC 34975. It has one arm severely tidally disrupted and pulled out from it by some distant collision. The arm wraps faintly around the western side of the galaxy then back north of the galaxy ending northeast of the galaxy. The area between it and the rest of the disk is faintly visible as well. Its redshift shows a distance of 370 million light years so it isn't related to NGC 3656 in any way. Just a coincidence that adds interest to the image.

ASK 236497.0 to the lower right is listed as having a candidate BH nucleus. BH at NED stands for black hole. Since most galaxies have a black hole in their nucleus I don't know quite what they are trying to say. Probably something like a candidate AGN?

PGC 034895 to the lower right appears to have two blue blobs at its north end. Are these star clouds? Are they the result of something it ate? Is there more than one galaxy here? I found nothing to answer my questions.

There are a heck of a lot of really distant galaxies at a billion or so light years in this image. One group is seen above PGC 34975, another group at the lower right corner and dozens of others scattered about the frame. If it is star-like but fuzzier than it should be or elongated it is a galaxy, not a star. Their great distance puts a lot of dust between us and them so they do get reddened by the dust. Look close in any part of this image and you'll see many of these. A couple hundred overall. Keep in mind, that due to the flat problem I am not going as deep into this image as I could with proper flats. Unfortunately, there's no way to take flats that cover this temperature range so this is the best I can do until I retake it under more steady temperature. But I have a ton of objects that haven't been looked at at all so that will have to wait for some time in the future.

I've since prepared an annotated image. NED shows a galaxy east of Arp 155 as a possible dwarf galaxy but then lists its distance as 1.29 billion light-years. That makes it some 130,000 light-years across, possibly bigger than the Milky Way we live in. It isn't the only one so listed but is the biggest. Why this discrepancy I don't know.

I measure ARP 155 as being about 90,000 light-years wide. It was discovered by William Herschel on April 14, 1789 but isn't in either of the Herschel 400 observing programs.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp155.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for ARP155

ARP156

Arp 156/ UGC 05814 belongs in his category for disturbed galaxies with interior absorption. I believe the latter refers to the dust lane. Arp's comment reads: "Very faint oval loop in north-following-south-preceding direction. "North-following" means northeast and "south-preceding" is southwest. NED classifies it simply as Peculiar. The CGCG catalog says of it: "Post-eruptive spiral with double core (blue and red), pronounced absorption line." I don't see that double core in my image or the Sloan image (only other color image of this galaxy I could find). unless this refers to the portion of the core above the dust lane (slightly red) and the portion below the dust lane which is less red though I'd not call it blue. http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=160.65848773&dec=77.4947972&scale=0.79224&width=512&height=512&opt=&query=

Other than the above I found virtually nothing on this object. It sits quite alone in northwestern Draco nearly a half billion light-years from us. This means the galaxy is huge. From one side of the plumes to the other it is 140 arc seconds (over 2 minutes) across. That puts it over 330,000 light-years across. Ignoring the plumes it is a more reasonable 120,000 light-years in diameter. Still likely larger than most galaxies. I suspect it got its size and its plumes from merging with other galaxies though I found no neighbors in its area. Did they all get eaten? NED has no redshift data on any other object in the field so I've not prepared an annotated image.

This is another Arp that was lost on my hard drive after getting misfiled due to not having calibration run automatically as the data was taken. In this case, my notes indicate I was going to revisit it for more data but that never was recorded in the database that controls what the scope images so it never happened. Rather than wait for next year I processed what I have so far as it is my normal exposure times. Though it is obvious that the luminance frames (well three of the four) were hit by clouds. Likely why I was planning on more data to help bring out the plumes. Green also suffered a nasty hit but I think I have the color reasonably close despite the skies attempts to thwart my efforts.

Arp's image is at: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp156.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for ARP156

ARP157

Arp 157/NGC 520 is located in the constellation of Pisces the fish below the Great Square of Pegasus. This one has been the source of some debate over the years. Today it is seen as two galaxies in the process of colliding and likely merging. But in Arp's time, it was seen as a single galaxy similar to M82 though oddly he classed M82 in his miscellaneous category while Arp 157 is classed as Galaxies (not classifiable as S or E) disturbed with interior absorption. So he was apparently on the fence with this issue. Even as late as the 70's the debate was unsettled. Comments like this were in the literature of that era: "Inspection of the original plate suggests that NGC 520 is not a collision of two galaxies but rather a system of the M 82 type (Sandage)". It appears the images of that era just didn't show the detail that today's do. In my image, you can clearly see two galaxies. One appears of the type of NGC 3628, the hamburger galaxy, in Leo. It's dust lane dominates and also hides the core same as with NGC 3628. The core of the other galaxy is seen to the northwest (upper right) with a more steeply tilted dust lane below it. The interaction has created lots of tidal distortions. The main one being a tail that first goes down then arcs to the east (left) and comes back up as a very faint fan. I've seen comments that it does or may connect to UGC 957 the big fuzz blob to the upper right of Arp 157. That isn't seen in my image though it may show with more exposure time. Arp 157 has a redshift distance of 90 million light-years while that of UGC 957 is 85 million light-years by its redshift. Close enough that they may have gravitationally interacted in the past. Though it's rather symmetrical shape would argue against that. Few galaxies in the image have redshift distances.

The galaxy was discovered by William Herschel on December 13, 1784. It isn't in either of the Hershel 400 observing programs, however.

Even the rather bright disk galaxy below and left of Arp 157, PGC 5195, has no redshift data I could find. About the only other object with redshift data is the quasar [HB89] 0121+034 at 3.7 billion light years. Follow a chain of stars starting at the kink to the left of the tidal tail. Two faint stars, a rather bright orange star, a somewhat fainter star then a bit of a gap brings you to the very blue quasar. All lie in a nearly perfectly straight line.

At the top of the page are several galaxy clusters. It appears their members overlap. I was unable to separate which belonged to which cluster as individual redshift data wasn't available. Most of these red galaxies along the top above Arp 157 probably belong to NSCS J012431+040205 with 61 members at a redshift distance of 3.5 billion light years. The other two are XDCS cm J012437.8+040022 at 3.94 billion light years and XDCS mf J012435.6+040107 at 4.46 billion light years.

5 asteroids are also in the image. Nearest Arp 157 to the west (right) is (53883) 2000 FN39 at a listed magnitude of 19.8 though it appears brighter than that. In the lower left corner is (58656) 1997 WT50 at magnitude 18.3. Along the bottom edge toward the lower left corner is (23843) 1998 QU106 at magnitude 16.6 so easy to spot. The remaining two are more difficult. (131277) 2001 FB69, magnitude 19.4, lies below the upper left corner near a rather obvious orange star. Right in the upper right corner is (35745) 1999 GZ30 at magnitude 19.2

Hubble has taken a great image of this galaxy. It can be found at http://hubblesite.org/image/2342/news_release/2008-16 and is south up so appears upside down. Note the star cloud easily resolved by Hubble made up of super hot very young stars along the top edge of the Hubble image. It appears as a blob near the top of the tidal arm in my image. I can't begin to resolve the stars thanks to our atmosphere. Since we appreciate being able to breathe I can't do much about its distortions. The Hubble page gives a different distance estimate of 100 million light years. Since Hubble has managed to resolve some stars its estimate may be more accurate than pure redshift estimates. If you have the bandwidth I recommend downloading the largest image.

ESA released their image of this galaxy taken with a scope with 100x the light grasp of mine and from atop one of the premier imaging locations in the world. Their image is at http://www.eso.org/public/usa/images/potw1048a/ I was rather surprised that their much larger scope under much better skies didn't do much better than I did. Their observatory that took their image (I don't know which of the two was used) is at:
http://www.eso.org/public/archives/images/screen/ib-la-silla05.jpg
The scopes are mounted high above ground level to avoid seeing problems at ground level. I did the same but am only up a bit over 16 feet due to zoning limits on the height of buildings around the lake -- and cost of course.

Arp's photo of the galaxy is at:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp157.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP157

ARP158

Arp 158 is NGC 523/537. It is a very strange galaxy. Arp put it in his category: Galaxies (not classifiable as S or E); Disturbed with interior absorption. I'm not sure what that means. Centaurus A (NGC 5128) also falls in this category though I won't be imaging it of course as it is always below my horizon. Redshift puts it about 200 million light-years away. Analysis of a type 1a that blew in 2001 (or I should say was seen here on earth that year) indicates about the same distance. That's about the only agreement on this galaxy I could find. Here are some Notes on it at NED.

"Post-eruptive, blue, 3 compact knots connected by bright bar, fan-shaped
jets and matrix' (CGPG)"

"Possibly a colliding or strongly interacting pair. Compact core."

"Peculiar spiral, with two nuclei on sides (east-west).
Chincarini G., and Heckathorn, H. M. 1973, Pub. A.S.P., 85, 568.
claim that the west nucleus is a foreground star,
but our measured redshift is similar to that of the east one."

It's quite obvious the westernmost object along the bar is just a foreground star. I have no idea where the idea comes from it is part of the galaxy or how its redshift could possibly be measured so poorly. The blob on the east end could be the core of a galaxy it is merging with. Wish we could see it from another angle. Seems to be virtually edge-on. NED classes it simply as peculiar.

Other than these notes and the articles they came from I found little on it. Thanks to better than normal seeing I was able to image this one at 0.5" per pixel though the seeing didn't hold for long. I really needed 20 minute subs as 10 contain too much read noise. Also, I normally consider 80 minutes the very minimum but only got 60 so this one is far noisier than I'd like.

This one appears to be part of the Pisces group though located just across the border in Andromeda. Arp 229 is also a member of this group.

The story of its discovery by William Herschel is quite interesting but too long to post here. Go to the NGC project page: http://www.ngcicproject.org/dss/dss_n0500.asp and scroll down to either NGC 523 or NGC 537 and click on the data button (not the image). Then scroll down to Historical Research Notes for the story. Think you have had a bad night at the scope? Seems William was having a really bad night at the telescope the night he recorded this one resulting in two NGC entries for one object. The night he got it correct was September 13, 1784. That resulted in the NGC 537 entry. Heinrich d'Arrest corrected Herschel's error for NGC 523 on August 23, 1862 and gets credit for this version. It isn't in either Herschel 400 observing program.

Arp's excellent image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp158.jpeg

14" LX200R @ f/10, L=6x10'x1 RGB=2x10'x2, STL-11000XM, Paramount ME

Related Designations for ARP158

ARP159

Arp 159/NGC 4747 is a very distorted galaxy in Coma Berenices not far from the famous Coma Galaxy Cluster, about 68 million light-years distant by redshift. By Tully-Fisher measurements, it is closer, about 40 million light years. I suspect this to be more accurate. I'll get back to why in a bit. Arp put this one in a category based on the dust clouds near the core rather than the tremendous star plumes. It is in his galaxies (not classifiable as S or E) disturbed with interior absorption. Centaurus A is the most famous galaxy in this class. Arp saw the northeast plume saying: "Very faint plume extending northeast." He didn't mention the shorter and fainter southwest plume. Nor do any of the notes at NED. The NE plume extends much further in my image than I can see it in Arp's image. NED classes it as SBcd pec.

Obviously, something happened to create these huge plumes and so disturb the galaxy. There's no hint of any galaxy in my image that could do it. But just beyond the image is an even larger disturbed galaxy, NGC 4725. Its redshift is almost identical to that of Arp 159. Analysis of its Cepheid variables as well as Tully-Fisher measurements put it at about 40 million light years. With both measurements the same for Arp 159 and NGC 4725 it appears quite likely these two tangled in the past. Tully-Fisher can be quite accurate with spirals seen at an angle as these two are. For the two to agree like this I suspect it is giving a more true distance estimate. The redshift being due to their common motion through space as indicated by their apparent interaction.

I imaged 4725 when I first went digital using the same scope and camera but different focuser and distance behind the main mirror. This changed the image scale. My filters were different as well, not nearly as well matched to the camera's spectral response nor did I take G2V data for them. I was in ignorance mode back then. This made color balance difficult. I reprocessed that image as best I could and made an attempt to combine the two images taken years apart. Having never tried this before and not taking either image with this in mind at the time the results aren't great but at least it does show the relationship of the two galaxies. The other galaxy with NGC 4725 is NGC 4712. It is a background galaxy with a redshift distance of a bit over 200 million light years. Obviously a distant background spiral galaxy.

NGC 4747 was discovered by William Herschel on April 6, 1785. NGC 4725 was discovered 4 days later on April 10, 1785 and is in the original Herschel 400 observing program. NGC 4712 was discovered by John Herschel on March 28, 1832.

My notes on NGC 4725 taken with my 10" f/5 on April 23, 1985 under fair but humid dimming skies with moonlight bothering using 50x reads: "Large, oval galaxy with star-like nucleus."

While the field is within the SDSS survey no distance data was found at NED for any galaxy in my Arp 159 image other than Arp 159 itself.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp159.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP159