ARP170

Abell 2572 > Hickson 94 > Arp 170

Arp 170 is located in the Great Square of Pegasus at a distance of about 525 million light years. Arp classed it under galaxies with diffuse counter-tails. It is part Hickson 94 which is part of the Abell 2572A a subgroup of Abell 2572. Only the two brightest are part of Arp 170 however. The northern one is classed as E1 while the lower one with the diffuse counter-tail is S0^0 pec. Both are also NGC 7578. One is 7578A and the other 7578B. But which is which is an enigma. The NGC Project and NED both claim the brighter is A. Both say the brighter is 0.6 magnitudes brighter. But they disagree as to which is the brighter! So Prof. Cory with the NGC Project says the northern E1 galaxy is A while NED and several other catalogs say it is the southern S0^0 galaxy. So which is the brighter? At first glance, it does appear the northern one is but when you consider the large tidal plume of the southern one it might be the brighter. It's certain the northern one is the easiest to see visually from all reports I have read. Did the Herschels see both? It's hard to say from their notes. To add to the confusion some catalogs that use the UGC designations use UGC 12478 for the northern one while others say it is UGC 12477 and of course they can't agree on the southern one either. But since the UGC is supposed to be in RA order that would make the northern 12478. Hickson assigned his galaxies by magnitude and agrees the northern is the brightest by giving it the H94A designation. But just when you think you have this figured out another issue develops. The Kanipe-Webb book agrees with NED that the northern galaxy is A but they assign it as Hickson 94B, while NED says it is A. My head hurts. You'd think all this would be settled by now. Arp had no comments on this entry nor did he enter into the identification debate. The PGC says the southern one is 70933 and the northern 70934. The galaxies were seen as one by William Herschel on September 18, 1784. It isn't in either of the Herschel 400 observing programs, however.

I'm not very certain of the color on this one. Fog rolled in during the initial exposure. It really hit when I started to take the green and then totally ruined the blue. So a couple nights later I retook the green and blue. It wasn't until I went to process this I realized the red was hurt by the fog as well. Since I have no measure of the loss of red to the fog I first tried a normal G2V correction and got a disaster showing the red was far worse than I thought. I then made a guess as to the red fog correction based on the spectral type of the K2 star in the image. But when I got it to the right color the galaxies were still odd. I tried some manual tweaking that helped greatly but am not all that sure of the color accuracy here.

While the SDSS hasn't covered this area this region is teaming with IR galaxies in the 2MASS catalog, many of which have good redshift data. While my color is likely not highly accurate I do believe the red color of nearly every galaxy in this image is correct. An IR galaxy need not appear red to our eye but they often do. That seems to be the case here. Nor does a red galaxy necessarily mean it is a strong IR emitter. Many in this particular field however are.

There are four other NGC galaxies in the image. All are members of the Abell 2572 group and are east of Arp 170. One, labeled NGC 7571/7597, has an identity crisis. Is it NGC 7571 as the RNGC says or is it NGC 7597 or is 7571 just non-existent? On the annotated image I've gone with NED and Prof. Cory saying it is both 7571 and 7597. In any case, that galaxy was first seen by Albert Marth on October 23, 1864. Later on September 25, 1867 Herman Schultz saw what is called NGC 7571 but what galaxy he saw is uncertain. You can read all about it at the NGC project http://www.ngcicproject.org/dss/dss_n7500.asp at the NGC 7571 entry.

There are two other NGC galaxies at the far left near NGC 7597. They are NGC 7598 an E or E3 galaxy with a redshift that puts it a half billion light-years distant. NGC 7602 an S? or S0/a? galaxy a bit over a half billion light-years based on its redshift. Both were discovered by Albert Marth on November 3, 1864.

I've prepared an annotated version. I've used NED's assignment of Hickson letters to the group, as mentioned above this doesn't agree with the Kanipe-Webb book as to A and B. Since it appears nearly all the galaxies have about the same distance as Arp 170, being part of Abell 2572, I've just identified the larger ones. Those few that are nearer or further than Arp 170 have their distance noted after the catalog name. Some have no redshift data. I've added NRS for No Red Shift data to the file name when this happened. All others are known to be about the same distance as Arp 170 and thus likely members of the same group. It's interesting they all have about the same color. Two galaxies close together aren't in the catalogs but two very nearby are. The brighter of the unlisted ones is barely within the error circle for a radio source, NVSS J231822+184352. This nearly marks the center of Abell 2572 the group to which most of the galaxies in this image belong.

I included an unusual galaxy, at least for its catalog designation, LT 32. This is the only designation for the galaxy in NED. It stands for Laird Thompson who compiled a listing of "Possible ring galaxies near rich clusters." There's 115 in the list. How this speck of a galaxy is seen as a possible ring galaxy is beyond me. The coordinates match to the pixel. Maybe longer exposures show a faint out ring I didn't pick up. In fact, what I imaged has the PSF of a star, not a galaxy so maybe the entire galaxy is too faint and I'll I picked up was field star atop it. NED classifies it a R (U) 0. The R likely is for ring but what the other two mean I have no idea. If anyone knows please let me know and I'll update this. Note the position is a bit uncertain. It points to a space between the object I've pointed to and the object to its left. That one is clearly a star so I went with the one on the right. Both are within the error circle of its position.

Arp's image taken under what looks like near perfect seeing atop Palomar Mountain.
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp170.jpeg
Ironic he'd waste such great seeing on such a low resolution object. Maybe he hoped there was something of interest this seeing would make visible.

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

Related Designations for ARP170

ARP171

Arp 171 and the galaxy cluster it anchors is located about 380 million light-years distant in the northeastern corner of Virgo. I rarely reshoot an object. There are so many new ones yet to explore I usually don't redo something. I made an exception in this case. Partly because the framing the first time missed some interesting galaxies and galaxy clusters to the north and secondly because conditions weren't great the first time so I didn't pick up much of the plumes. I'd hoped to add this data to the earlier image for the area of Arp 171's plumes. Unfortunately, the data was so unequal it seemed to hurt the plumes rather than help them so I gave up that attempt. Apparently, most of what I thought were plumes were mostly over processed noise in the original image.

A new study says that while all stars formed in galaxies, half of them have been ripped from their home galaxy and now live alone in space. Many of the stars in these plumes may be destined for this same fate, never to fall back into their birth galaxy.

Arp 171 consists of the two interacting galaxies IC 1042 and NGC 5718. Both are S0 rather than elliptical galaxies. Though there's some question about this indicated by the ? and : in the two classifications. NGC 5718 is the bright cluster galaxy anchoring the large galaxy cluster SDSS-C4-DR3 1014. Ned shows it with 105 members but gives no size. It certainly is larger than my image.
Arp put this pair under his heading for Galaxies with diffuse counter-tails. Arp's image http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp171.jpeg strangely is framed such that most of the plumes lie outside its edges. While the edges of the plumes are rather fuzzy, especially to the northwest I'm quite confident it measures more than 1 million light-years across. I can't recall measuring any coming even close to this size.

NGC 5718 was discovered by William Herschel on April 30,l 1786. It isn't in either program. IC 1042, IC 1039, IC1041 and IC 1043 were found by Stephane Javelle on May 28, 1891.

For laughs, my pathetic first attempt from 2010 is at: http://www.spacebanter.com/attachment.php?attachmentid=3403&stc=1

The field is very crowded with annotated objects. In a few cases, I've drawn a line to an object when it appears that wasn't necessary, as in the case of the UvES object at 9.45p billion light-years. If you look very closely you will find two objects at these locations with the line going to the one that is labeled. So if a line appears unnecessary or seems off center look closer and you'll find a second object is involved. NED listed quite a few Emission Line Galaxies. They were mostly very faint and hard to see on the processed image. Most were at distances of 4 to 8 billion light-years. Since the image was already rather cluttered I listed only a very few of them to give a sampling of what they are like. I omitted about 100 of these as it would have made the image so cluttered as to be nearly useless.

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

Related Designations for ARP171

ARP172

Arp 172 is a pair of obviously interacting galaxies in the Hercules Cluster that Arp put in his category for galaxies with diffuse counter tails. Tidal plumes weren't understood at the time so this is Arp's description of its visual appearance. Some sources consider both galaxies as IC 1181 with the northern one IC 1181A and the southern IC 1181B. Others consider it 1181 only the southern galaxy and IC 1178 either the northern or both. NED classifies the northern galaxy as S0:- pec? and the southern as SAB(rs)0/a. Both were discovered by Lewis Swift on June 3, 1888.

This data was taken on September 13, 2007. I didn't have the tools to do it justice back then. I need to reshoot this one. It also contains ARP 71, Arp 122 and Arp 272. Details are in the annotated image. The annotated image shows details on many other galaxies in the cluster and beyond it.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp172.jpeg

14" LX200R @ f/10, L=6x10' RGB=3x10', STL-11000XM, Paramount ME

Related Designations for ARP172

ARP173

Arp 173/UGC 9561 is a pair of galaxies about 410 million light-years away in the southeastern corner of Bootes. The northern galaxy is MCG +02-38-20/PGC 53053 while the southern is MCG +02-38-19/PGC 53054. The northern one is classed S0 by NED which I find puzzling as it seems to have too much structure for that classification. The southern one is classed simply as S? Except for the plume, it seems to fit the S0 class. Makes me wonder if NED reversed these classifications. The PGC designations also appear reversed as normally they are in RA order but that is not the case with these two. In any case, Arp put this in his class for galaxies with narrow counter tails. There is certainly a nice narrow plume heading south and a bit west from the southern galaxy. There appears to be a broad plume toward the northern galaxy as well. Several plumes extend in various directions from the northern galaxy. Obviously, these had a close passage by each other in the recent past. One paper indicates the authors think the northern galaxy should be designated as a Seyfert 2 galaxy. NED apparently disagrees as they don't indicate this in their classification.

Well to the southeast of Arp 173 is the strange distorted galaxy MAPS-NGP O_502_0362090. This is the only designation given for it at NED. This surprised me as it is well imaged in the Sloan survey yet NED doesn't pick it up in that survey. Quite common I've found, especially with blue galaxies of low surface brightness such as this one. There's no redshift data on it so I can't tell if it is related to Arp 173 or not. I'm surprised Arp ignored it. It certainly is peculiar looking.

Just north of this galaxy is an object listed as an IR source in the 2MASS catalog and a galaxy and quasar in the Sloan Survey. I've noted it as IR/G/Q in the annotated image. Its redshift puts it about 2.9 billion light-years away so it is pretty big and bright for a galaxy. I see no hint of a brilliant quasar at its heart, however.

West and a bit north of Arp 173 is a very blue disk galaxy also at about 410 million light-years. It too has very low surface brightness. It was picked up by the Sloan survey and is in other catalogs including LEDA as LEDA 4550853. It appears rather normal however so doubt it has interacted with Arp 173.

In the southwest corner is asteroid (33666) 1999 JO94 shining at an estimated magnitude 18.6. You'll note there are red green and blue frames on either side of the luminosity frame. Due to weather and meridian issues, I took the first red, green, blue series then the 4 luminance frames. I was sure clouds were going to cut off my imaging. By then I had to move to the other side of the meridian. I did so and took the remaining three color images while the clouds never came rolling in, whew.

In the annotated image there's a very red but faint (magnitude 21.2) galaxy with a redshift of z=.484314 which puts it about 4.9 billion light-years away light travel time. It is directly south of Arp 173. In the lower right corner beyond the asteroid is a very blue star that is a quasar with a redshift of z=2.357128 which puts it at 10.9 billion light-years light travel time. Just beyond it is an even more distant quasar. It has a redshift of z=2.611678 and a light travel distance of 11.2 billion light-years. While the light took 11.2 billion years to reach us it wasn't that far away when the light left the quasar over 11.2 billion years ago. The universe has been expanding. The quasar was less than 6 billion light-years distant when the light left it. "Today" if the quasar even exists this expansion has moved it to where it is nearly 20 billion light-years from us. This leads to some amazing conclusions. 11.2 billion years ago the universe was only 2.7 billion years old and thus any astronomer of that time could see only 2.7 billion light-years away. Actually less but I won't go into that issue. Yet this quasar was 6 billion light-years away. It was beyond the observable universe to such an early astronomer. Given enough time though, as the universe aged such an early, and very long-lived, astronomer, could eventually see the quasar, it was now within the observable universe. But "now" it is nearly 20 billion light-years distant and the universe is only 13.7 billion years old. Given enough time would we see the light it is emitting today? No, we will never see that light. For it to have moved from about 6 billion to 20 billion light-years away (actually we are both moving apart) it has moved about 14 billion light-years in 11.2 billion years. That means we are now moving apart faster than the speed of light! Thus, the light it emits "today" is actually getting further from us each day even though it is moving at the speed of light. The race is lost even before it has begun. Now, this does not violate Einstein's relativity. That says nothing can accelerate through space faster than the speed of light in a vacuum, it puts no restrictions on how fast space itself can expand. Space is free to expand at any rate even one far exceeding the speed of light.

In the upper right corner are several galaxies at about 680 to 690 million light-years. This group has more than a dozen members, most of which are off the image to the northwest. I found no recognized cluster in the area, however.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp173.jpeg

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

Related Designations for ARP173

ARP174

Arp 174 is a pair of galaxies with a large tidal plume. It is also known as NGC 3068 and is located about 300 million light-years away in the constellation of Leo. Arp classifies it under Galaxies (not classifiable as S or E): Narrow counter-tails. Why this plume is a counter tail and others aren't I'm not sure. It's hard to say if the plume comes from the small companion or the larger one and by perspective passes over or behind the smaller galaxy. There is a faint connection between the two. If they come from the small companion then yes, it could be a counter tail assuming the connection between them also comes from the smaller galaxy. Arp's only comment on the pair is: "Smaller galaxy very condensed." NGC 3068 (northern part) was discovered by William Herschel on March 12, 1785 but isn't in either Herschel 400 observing programs.

The NGC Project considers NGC 3068 to only be the larger galaxy but NED applies the name to both. The smaller one is also known as LEDA 087670. It is classed simply as an elliptical galaxy. The larger one is classed as S0 pec. To me, it appears the source of the plume as it has other obvious tidal features all about it.

The galaxy directly east of the bottom end of the plume is 2MASX J09584551+2848466 at about 1 billion light-years. Directly east of it is an orange star, about the same distance east and a bit more brings you to a rather white star with a fainter one above it. The brighter one is actually quasar SDSS J095854.99+284858.4 at 9.9 billion light-years. Up and a bit left of Arp 174 is a small arc of golden near starlike galaxies along with a bunch of fainter ones in the background. The middle one is brightest. It is SDSS J095849.29+285615.4, a 20.2 magnitude galaxy some 3.7 billion light-years away.

There is one asteroid in the upper left quadrant. It is (193683) 2001 EO14 with a predicted magnitude of 18.3.

SDSS image:
http://astronomerica.awardspace.com/SDSS-20/NGC3068A.php

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp174.jpeg

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

Related Designations for ARP174

ARP175

The Tower of babble bit me again. I reimaged Arp 175 without realizing it as I also had it under its IC numbers. This turned out to be a good thing, however. The original data was taken on a night of poor transparency while the new image was under better conditions. While they weren't framed the same at all I've managed to include a bit over half of the first images data in the image stack so part of the image uses just the new data and part all the data. The result is I can bring out a lot more of the plume.

Arp 175 is considered to be three interacting galaxies also known as Zwicky's System. But that was before redshift measurements that now show that IC 2483 has a very small redshift compared to the other two putting it less than 10% the distance of the other two. Of course, the fringe makes a big deal about this assuming it is established they are all at the same actual distance. That, however, isn't all that likely at all.

See http://ned.ipac.caltech.edu/level5/March02/Zwicky/Zwicky3.html for a very old discussion on this. Note their enhancement of the POSS II blue plate seems to show a connection to IC 3483 that's almost as bright as the rest of the plume. Arp said the couldn't see the plume going beyond 2/3rds the way to IC 3483. My new image shows a rather abrupt end to the plume about where Arp put it. I don't see it continuing to IC 3483 at all.

What is certain is there's a connection between IC 3481 and IC 3481A. This is rather confined with no hint of it ballooning out. Yet beyond IC 3481A, we have that huge arcing plume. I'm going to speculate here that this plume is not what everyone says. The area is full of very small dwarf galaxies with the same redshift as these two large galaxies. Could one of them have been torn asunder by the gravity of these two and we are seeing the remains of this third galaxy? To me, the plume doesn't fit with the stars obviously part of the IC 3481-81A system's plume. It seems to me to be entirely separate. I wasn't able to find any redshift determination for this plume. That might answer this puzzle.

I couldn't find any images deeper than mine on the net. But even if the plume does extend to IC 3483 that doesn't mean IC 3483 is involved. It likely is near in the foreground and its just coincidence we see it from this perspective. If it is all one vast plume it stretches some 350 million light-years. Now that's some plume!

Another puzzle in the image which I discussed the first posting is of VCC 1464 which appears many times at NED under various designations. Two have a redshift of z=1.1 which puts it over 8 billion light-years away. But NED says the redshift is likely in error. One entry calls it a quasar at 18th magnitude. Quasars are starlike points so an 18th magnitude one would shine brightly through the faint fuzz of this galaxy yet is not there. Seems like some major error is involved here that has yet to be straightened out. In any case, there's no way I could pick up a dwarf E4 galaxy at 8 billion light-years. That famous Chinese astronomer Sum Ting Wong has struck again I'm afraid.

IC 3481 was discovered on May 10, 1904 by Royal Frost an American astronomer working from the Arequipa observatory in Peru. He's credited with finding 454 IC objects. He discovered IC 3483 at the same time. I don't know who found IC 3481A.

NGC 4528 was found by William Herschel on March 15, 1784. While it is considered a lenticular galaxy and certainly appears to be one in all images I found I was surprised that applying my usual stretch for bright cored galaxies a barred spiral appeared! While it has some characteristics of an S0 lenticular galaxy it also has a bar and ring seen in some barred spirals. It seems to be a hybrid of both types.

Oddly NGC 4503 is classed as such a hybrid being SB0-: Yet I was unable to pull a bar out of it. It does have a rather featureless bright disk around the core that is quite white, then a dark ring and the outer disk is rather red in color. The inner bright disk seems twisted about 15 degrees clockwise from the outer red disk. It was discovered March 15, 1784 by William Herschel and isn't in either Herschel 400 list.

IC 3470 is the remaining IC galaxy in the frame. Its a dwarf E0 galaxy with an obvious nucleus. No surprise here, it was also found on May 10, 1904 by Royal Forest.

I've noted 4 asteroids on the image. All are from the April 2014 data. There were two in the original image but due to how I combined them I accidentally deleted them from the combine. I'd meant to hide the new image in that area to allow them to be better seen and instead hid the asteroids. Somehow I didn't notice until I started writing this weeks later.

14" LX200R @ f/10, L=8x10' RGB=4x10' (but see text), STL-11000XM, Paramount ME

Related Designations for ARP175

ARP176

Arp 176 is a pair of interacting galaxies also known as NGC 4933 though this designation includes a third non-interacting galaxy. The IC catalog lists the two interacting galaxies separately as IC 4173 and IC 4176 west to east (right to left). They are located about 160 million light-years away in the constellation of Virgo. Arp put these in his category: Galaxies (not classifiable as S or E): Narrow counter tails. His comment on the pair is simply: "Companion galaxy [IC 4173] very condensed." Most notes seem to consider the streamer as coming from IC 4173. I'm not that convinced. Tearing out a tidal arm from such a tight E0 galaxy isn't easy. Tearing one from the far less dense IC 4176 seems to me far more likely.

Most sources class the main galaxy as S0/a. The dust lane I picked up seems to cross the galaxy at a very odd angle. My seeing was awful the night I took this both because it is low in my sky and due to a nasty haze layer that moved in mid-exposure. It really ruined my color data. I tried to salvage it as best I could but the red data was very weak and the green noticeably weakened. I took the blue first before the haze was bad. As a result, getting a good color balance was impossible. I need to reshoot this one next year under better conditions.

NGC 4933 was discovered by William Herschel on May 9, 1784. It isn't in any of the Herschel 400 observing programs. It was later discovered at somewhat different coordinates by Guillaume Bigourdan on April 16, 1895 and listed as IC 4176. He discovered IC 4173 at the same time.

The third non-interacting galaxy is MCG -02-33-103. It shows a similar redshift as the other two but is apparently far enough removed from the other two it isn't involved in the interaction. To the east of Arp 179 is the barred spiral MCG -02-33-105. It is incorrectly identified as IC 4134 in the Kanipe-Webb book on Arp galaxies*. I find no redshift data on it so can't say if it is part of the NGC 4933 group or not. Note that in researching the group I found no consistency in which member was A and which B. It was about a coin flip which a paper would consider to be A. All agreed the tiny eastern galaxy was C. Thus I went with the IC and MCG designations.

Below Arp 176 is a blue edge on or SO galaxy. The excess blue may be due to haze blocking red and the strong red glare from the nearby G5 star which is obviously too blue. Getting rid of its red haze skewed color beyond my ability to rebalance it in this part of the image. It is LCRS B130109.0-112106 at about 270 million light-years. The round puff of a galaxy near the G5 star is LCRS B130102.8-111941 of unknown redshift. West of Arp 179 is NPM1G -11.0360, a strong IR emitting galaxy of unknown redshift. Further west near the right edge is 2MASX J13025195-1129599.

*While some sources do show this galaxy as IC 4134 the NGC project, Seligman and NED have identified it as being NGC 4920 which is just out of my field of view. See the NGC Project for the details. Click on the data button for NGC 4920. http://www.ngcicproject.org/dss/dss_n4900.asp

Arp's photo showing several dust lanes I lost to my seeing is at:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp176.jpeg

14" LX200R @ f/10, L=4x10' R=1x10 GB=2x10, STL-11000XM, Paramount ME

Related Designations for ARP176

ARP177

Another twofer image. I'll start with Arp 177 since it is near the center of the image. At the time I didn't realize Arp 302 was also in the field or I'd have moved the field to get them both better centered. These galaxies are in Bootes.

Arp 177/MCG +04-35-016 and MCG +04-35-17 fall in Arp's class; Galaxies with narrow counter tails. Arp's comment reads: "Very small plume comes off companion galaxy opposite larger." It appears the blue plume to the north-northwest coming from MCG +04-35-016 is the "very small plume" while the large diffuse plume to the east of MCG +04-35-17 refers to the "opposite larger" part of the comment. The western galaxy with its plume reminds me of a comet. Redshift data is only available for the western (-016) comet-like member. That puts it at about 460 million light-years. I found very little on this pair. NED made no attempt to classify either galaxy.

Arp 302/UGC 09618a and b (b is the north member) is in Arp's category for double galaxies. Arp had no comment on this pair. They appear to be barely interacting. Some star plumes seem to be starting as there is a halo of stars around both galaxies. The northern member is a starburst galaxy. It's not necessary for an interaction to start a starburst but it certainly helps! This pair is also about 460 million light-years distant so both of these are part of the same local group of galaxies. NED classes the northern one as Sb with strong HII emission and a LINER spectrum. Signs of a disturbed galaxy. Problem is the southern member is rather normal though its spiral arms are a bit kinked. It is classed as Sc. I've attached a Hubble image of this pair.

There is very little information on this area. Sloan shows about 3000 galaxies in the area but has little on any of them. The only other galaxy with any redshift data is the edge on galaxy north of Arp 177. It is UGC 09606 and is in the flat galaxy catalog as FGC 1828. Seems to have too big of a core to make that catalog. Apparently not. A faint hint of a dust lane can be seen crossing the core area but I couldn't pull it out of the disk. It is classed Sbc by NED with a redshift that puts it much closer at 230 million light-years.

North northwest of Arp 302 is a small, very orange galaxy surrounded by a lot of faint galaxies as well as some much closer galaxies. One of the close ones is a very blue spiral with an orange edge on disk galaxy to its right. The orange galaxy I'm referring to is the distant elliptical galaxy almost due east (left) of the blue spiral. It anchors the galaxy cluster NSC J145649+244122. NED shows it as richness class 2 (80-129 galaxies) with a distance of 1.5 billion light years. The galaxy is SDSS J145651.46+244203.5. There's no redshift given but since it is considered to anchor the cluster its safe to assume the same distance. The blue spiral is MAPS-NGP O_383_0185334. That's the only catalog entry NED has for it. It is not in the Sloan catalog though the westernmost point of its faint arm is listed in NED as a separate galaxy. Looks like a bright knot to me. The orange spindle is MAPS-NGP O_383_0185301. Again, it's not in Sloan either. The rest of the field is just as frustrating.

Sorry about my stars. Somehow I managed to turn off PEC and since I don't guide the result is rather imperfect stars. I need to redo this one and get round stars. Maybe that's why the dust lane in the flat galaxy is so hard to detect.

Arp's image of #177
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp177.jpeg

Arp's image of #302
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp302.jpeg

14" LX200R @ f/10, L=6x10 RGB=2x10x3, STL-11000XM, Paramount ME

Related Designations for ARP177

ARP178

Arp 178 consists of three galaxies NGC 5613 (upper), NGC 5614 (lower) and NGC 5615 (inside NW halo of NGC 5614). These are located in the constellation of Bootes. NGC 5613 is nearly 400 million light-years distant while the other two are a bit less than 190 million light-years away. Arp put these in his category of galaxies with narrow counter tails. His comment reads: "Ring off center, broad ejected plume from condensation in ring."

Most papers of the era of Arp's Atlas and prior consider NGC 5614 as interacting with the northern galaxy (5613). We now know that with 5613 having over twice the redshift this isn't the case. It is unrelated but worthy of its own entry in the atlas. It is classed as (R)SAB(r)0+ by NED and the NGC project agrees but leaves off the + sign. At first glance, it appears to have a faint outer ring. But look closely and you see it is really two very extended spiral arms that nearly overlap. One starts at the 11 o'clock position and goes around to the 4 o'clock position. The other starts at 5 o'clock and goes around to the 10 o'clock position. In both cases, the ends are further from the core than the other arm inside it. This may be easier to see in the Sloan image stretched a bit differently than my image. What caused this? There seems no likely source. Prior to its redshift being determined, it is easy to conclude that NGC 5614 caused it. Now it is a puzzle.

The main feature here is NGC 5614 a very large tightly wound spiral with an off-center core and huge plume. NED and the NGC Project classes it as SA(r)ab pec. The plume seems possibly related to NGC 5615. It certainly is due to a gravitational interaction in the recent past. The off-center core causes Arp's "ring off center" comment. At first, I thought it might be that this was a case of a merger with inner arms rotating counterclockwise and outer ones turning clockwise but I found a rotation curve that says all is rotating the same way. It is just the core being off center from the first ring that creates this illusion. Still, I am having a hard time seeing it. I believe it a merger in progress with NGC 5615.

The condensation Arp refers to is NGC 5615 and has a redshift that puts it about 3 million light years more distant than NGC 5614. NGC 5615 is not classified at NED, NGC project says S? I can't see enough to try classifying it so have to agree with NED. Is NGC 5614 in the process of digesting NGC 5615. I saw suggestions of this in early papers but nothing conclusive. One paper suggests that the tightly wound arms of NGC 5614 might be due to an unusually massive black hole at its core. No reason was given other than it appears such galaxies tend to have larger than expected black holes when this has been measured. Pretty speculative to me. In any case, it is an interesting galaxy as is NGC 5613.

After I wrote this Adam Block posted an image of this galaxy taken by the 32" scope at the Mt. Lemmon Sky Center observatories. It clearly shows NGC 5615 is broken into several bright cores. It also shows the bright blue arcs in NGC 5614 far more clearly. I now think 5615 is quite likely the remains of a galaxy torn asunder by 5614, even the core of it is being ripped apart by tidal forces. I wrote Adam with this suggestion and he agreed it is likely the case. The three million light-year difference in redshift is likely due to relative motion and difficulty of assigning a redshift based distance to a mess like this.

Another galaxy at about the same distance of NGC 5514-5 is to their NE. Several galaxies of the same distance as NGC 5513 are in the frame as well. It appears they are two different groups. Several galaxies at 1 billion light-years are also found around the image. While I see several groups of galaxies in the image only one, the northwest corner is listed as a galaxy group. That is MaxBCG J215.67259+34.98489, is cataloged. It is shown to be a group of 20 galaxies in an unknown area. It is listed with the same position as its apparent anchoring galaxy though their redshift distances are slightly different. See the annotated image for these.

Normally I think of NGC galaxies as being closer than say a half billion light-years, far closer in many cases. But NGC 5609 at 1.31 billion light-years is an exception. NED lists its green magnitude as 16.3 while the NGC Project puts its visual magnitude at 15.7. Since green is usually used for this I can't explain the difference. Still, this one should be visible in larger amateur telescopes from a dark site, say a 16" or larger. Young eyes may glimpse it with less aperture if the brighter magnitude is correct.

NGC 5609, 5613 and 5615 were discovered by Binden Stoney on March 1, 1851. NGC 5614 was discovered by William Herschel on May 1, 1785. It isn't in either of the Herschel 400 observing program.

Often, in my annotated images, two similar galaxies are side by side. Only one though has a redshift published. I often get asked, "Isn't it reasonable to assume the other is at the same distance?" No, it isn't. A good example is in the lower corner of my image where two rather similar galaxies do have redshift data and one is over 3 times further away than the other yet appears only very slightly smaller. Assumptions are very dangerous in this business.

Yet again I happened to check a galaxy in my image that NED doesn't seem to know about. It lists over 5000 galaxies in this field, many too faint for me to pick up, but see Adam's image which does see them and more, on this rather poor night. Yet it missed the one in the northwestern corner of my image marked with a question mark. The star to its left and a bit north is listed but not the galaxy. Sure wish I knew why this happens. There are likely others. I don't check very many for this trait yet find one in a rather high percentage of my images. Note that most of the faint "stars" in the image are actually galaxies that are listed in NED but without redshift. Which is good as otherwise the image would have so many labels as to be useless.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp178.jpeg

Adam Block's image with the 32" telescope at the Mt. Lemmon Sky Center
http://www.caelumobservatory.com/gallery/n5613.shtml

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

Related Designations for ARP178

ARP179

Arp 179 is the object in the center of my image. Of that I'm certain. But what other catalog names it has is totally scrambled. Each source claims the others are wrong and they don't begin to agree. More on that in a bit. First I'll go with what we do know.

Arp classified this one under Galaxies (not classifiable as S or E): Narrow filaments. The class preceding it is narrow counter-tails. I'm not sure of the distinction. Arp's comment on it is "Condensed offset center." Looks more like a galaxy with a tidal plume to me but we know a lot more about such features than was known when Arp put this atlas together. The galaxy is located in the northwestern corner of the constellation Eridanus not far from M77 (Arp 37).

After this, things get muddled but good. If you ask NED what galaxy is Arp 179 it will take you to a different galaxy. It is in the cropped image. It is the one west and a bit north of the real Arp 179. It lies between an orange star to its lower left and a pair of white and blue stars to its upper right. This galaxy NED says is NPM1G -04.0134 as well as LEDA 175747 and, of course, Arp 179. The Kanipe/Webb book on the Arp Atlas says Arp 179 is NPM1G -04.0134 but points to the right galaxy. To find the real Arp 179 you have to tell NED to go to PGC 11432 or NPM1G -04.0135. Kanipe/Webb say PGC 11432 is an incorrect identification of Arp 179. So I checked The Sky's database. It agrees with NED saying it is PGC 11432 and goes to the correct location for the real Arp 179. It says LEDA 175747 is the galaxy between the two stars that NED says is Arp 179. SIMBAD goes to the right location when you ask it to take you to Arp 179 and says it is APG 179 (Stands for Atlas of Peculiar Galaxies which is Arp's atlas) rather than ARP 179 and LEDA 11432. It uses LEDA as the prefix for PGC galaxies so agrees it is PGC 11432. It says the galaxy between the two stars is LEDA 175747/NPM1G -04.0134 same as NED. Oddly the POSS site http://stdatu.stsci.edu/cgi-bin/dss_form/ when using SIMBAD to resolve object names finds the wrong galaxy. Why SIMBAD gets it right one place and wrong another I don't know.

So I'm going to say Kanipe and Webb may have this one wrong due to NED saying LEDA 175747/NPM1G -04.0134 is the same as Arp 179 but using the wrong galaxy for Arp 179. So I'll use the data for PGC 11432/NPM1G -04.0135 for Arp 179. NED has no classification for it but does show a redshift distance of 193 million light years. It is also listed as 2MASX J03020046-0441257 so is an IR strong galaxy. A good indication of a past interaction that is creating a lot of hidden star creation probably in or near its core. The other galaxy, the pseudo-Arp 179, I'll call it, LEDA 175474, is also listed by NED to be an IR source. But no distance data is available. Could they be related? No way to know, unfortunately. It isn't distorted so I doubt it created the plume. It appears to be to likely be far more distant but without more data that is only a very poorly supported guess.

Arp 179 is the only galaxy in my image with redshift data. What created the plume? I could find no obvious candidates within 3 degrees. Only 2 galaxies at about the right distance were turned up in NED within a 3 degree radius. MRK 1065 44 minutes away and KUG 0306-026 at 167 minutes. MRK 1065 is a SB0 galaxy noted as peculiar. I really didn't see much to indicate an interaction in the DSS plates, however. I suppose the plume could be the result of a merger. I found nothing to support this guess nor negate it either.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp179.jpeg

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

Arp's purpose in putting together his atlas was to help show the need to understand what is going on in peculiar galaxies. This has happened in general. We have a much better, though still somewhat incomplete, understanding of how galaxies get their peculiar features. But not all of his galaxies have been studied in any detail. This is one of the ignored ones it would seem.

Related Designations for ARP179