ARP166

Arp 166 is composed of two interacting elliptical galaxies NGC 750 and NGC 751 (lower). Both are classed E pec though one source says they are two normal E0 galaxies. While the NGC project classes them as E1 and E respectively. Redshift data puts them about 225 million light-years away in the constellation of Triangulum. Arp put the pair in his category; Galaxies (not classifiable as S or E), with diffuse elements. Note the bright short bridge between the two galaxies. Arp didn't mention this feature, however. His only comment refers to a third galaxy saying "Small spiral at end of plume." The galaxy wasn't cataloged at the time of Arp's comment. Now it is known as 2MASX J01572652+3314452. I find little on it, however. It is likely unrelated to Arp 166 however. Did it have anything to do with the plume? I doubt it as the interaction of the two elliptical galaxies could easily account for it though its alignment is suggestive of more than a coincidence. NGC 750 was discovered by William Herschel on September 12, 1784. It's not in either Herschel 400 observing program. He found others in this field that night as well. NGC 751 was discovered by Bindon Stoney on October 11, 1850. He found several others in this field that same night as you will see below.

There are many other galaxies in the field but many of them, other than the brightest or IR galaxies aren't cataloged at NED. Several though are NGC objects. At the top of the image, partly out of frame is NGC 761, an SBa galaxy about 218 million light-years away so likely related to those in Arp 166. It was discovered by Bindon Stoney on October 11, 1850. The double star below it is NGC 760. In the rush to find and catalog galaxies many such double stars were seen as galaxies, some single stars as well. The misidentification was made by Ralph Copeland on December 19, 1873. He was using Lord Rosse's 72" scope at the time yet still made the mistake. Photography has greatly reduced but not totally eliminated such errors.

NGC 739 is the S0? galaxy 40% of the way to the upper right corner. It is about 200 million light-years away per redshift data. It was discovered by Ralph Copeland on January 9, 1874. Copeland got its position in relation to NGC 750 correct but then described it is south preceding rather than north preceding. This has led to some catalogs considering it lost but since its coordinates in relation to NGC 750 are correct there's no doubt this is the galaxy he saw.

NGC 736 is the large elliptical galaxy toward the lower right. Notes refer to an outer halo or pseudo outer ring. Does this include to the odd plume to the north that spreads out east and west at the top making a ring arc? That reminds me of the Umbrella Galaxy, Arp 189/NGC 4651. Its redshift indicates a distance of about 190 million light years. Could the plume be due to a galaxy it ate? That is what caused the Umbrella Galaxy's similar plume. It was discovered by William Herschel on September 12, 1784. It isn't in either Herschel 400 program. NE of it is NGC 738 at 189 million light-years, a much smaller, elliptical red compact galaxy. To the southeast of NGC 736 is NGC 740 described as a very red spindle and classed SBb?. Redshift says 199 million light-years. Other measurements vary between 178 and 215 million light-years with a weighted average of 201 million light years in good agreement with RS data.

Another NGC galaxies around NGC 736 is NGC 738. NED doesn't classify it. The NGC project says C which likely stands for compact. Seligman says S0? which seems more correct to my eye. It was discovered by Bindon Stoney on October 11, 1850. NGC 740 is listed as Sb? or SBb??. It was discovered by William Herschel the same night he found NGC 736, September 12, 1784 according to some sources. Others say he didn't see it and it wasn't found until the night that Stoney found NGC 738. Seligman votes for Stoney. It isn't in either Herschel 400 programs. The same night Stoney found stars within NGC 736 that are recorded as NGC 737. Some sources call all three NGC 737 while others say it is just the center star.

Then there's NGC 733 also found by Stoney the same night as the others he found. Most likely it is the star the annotated image points to but some sources equate it with PGC 7255 so I drew lines to both. To add to the confusion NED indicates the star is PGC 7255 and NGC 733 while my The Sky program shows the galaxy as both as does SIMBAD.

Some of the fainter galaxies of interest include 2MFGC 01479 (2MASS Flat Galaxy Catalog) which is 70% of the way from Arp 166 to the 15th magnitude NGC 739. In K band IR light this little guy shines at magnitude 14, a full magnitude brighter than NGC 739 in visual light! A short hop east and a bit north brings you to VI Zw 116 just 6" south of a star. It is a Red spherical compact galaxy that is also an IR bright galaxy.

The asteroid north of Arp 166 is (126304) 2002 AX119 at magnitude 18.6.

Besides the full image, I've included a 125% enlarged crop of the pair which shows the bridge between them a bit better than the normal size image. It also includes the asteroid and an inset of NGC 736.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp166.jpeg

14" LX200R @ 1/10, L=4x10', RGB=2x10"x3, STL-11000XM, Paramount ME

Related Designations for ARP166

ARP167

Arp 167 is a pair of interacting galaxies located in Cancer, just east of M44, at a distance of about -- Houston we have a problem. There seems to be some uncertainty about these two galaxy's distance.

The two galaxies are NGC 2672 and NGC 2673 right to left. NED classes them as E1-2 and E0 pec respectively. Arp put them in his class of Galaxies with Diffuse Counter-tails saying; "Companion galaxy very condensed, has curved plume." NGC 2672 was discovered by William Herschel on March 14, 1784. It isn't in either Herschel 400 observing program. NGC 2673 was discovered by George Stoney on December 19, 1849.

Now back to the problems. While I called them interacting galaxies some papers say they are non-interacting. I see two reasons for this. First only NGC 2673 seems distorted. You'd think if they really did interact NGC 2672 would show some sign of it but I don't see any. The other reason is the redshift distances are different. By redshift, NGC 2672 is about 211 million light-years distant while NGC 2673 about 185 million light years. Relative speed in a galaxy group, however, can vary by this much and more. So it could be they had a fast interaction due to their high relative speeds. Still, you have the problem of NGC 2672's lack of apparent distortion. Yet most sources do consider them interacting and one puts them both at a distance of about 167 million light-years using the D-Sigma method. See http://adsabs.harvard.edu/abs/1994AAS...185.5217G for more on how this works for elliptical galaxies. Does it work for peculiar ones? Or was this just a measurement of NGC 2672 and NGC 2673 was assumed to be the same distance? I can't tell from the abstract. For now, I'll say they are interacting as I don't see any other candidate for the distortion. A large galaxy can survive such an interaction without much distortion.

The two spindle galaxies on the right (west) side of the image are NGC 2667/IC 2410 (lower) and NGC 2667B/IC 2411 (upper) at 195 and 211 million light years. About the same as the two galaxies in Arp 167. Obviously, these two aren't interacting. NGC 2667 was discovered by Heinrich d'Arrest on February 18, 1862. It was later photographed along with IC 2411 by Max Wolf on January 13, 1901 and given its IC number. Due to an error in position by d'Arrest, it wasn't realized these were the same galaxy until after the NGC was released. NGC 2677, to the southeast (lower left) of Arp 167 is the other major galaxy in the image. It splits the difference at 206 million light years. It was discovered by John Herschel on March 17, 1831. Certainly, these are all part of the same group.

Zwicky shows a galaxy cluster centered about 7 minutes south-southwest of Arp 167 with over 250 members and a distance of about 200 million light years. It covers an area almost 2 degrees across so goes far outside of my frame. It is listed as UGCl 131/ZwCl 0846.3+1910.

I've provided an annotated image showing distances to (G) Galaxies and (Q) Quasars. As usual, the label is to the immediate right of the object when possible. A line points to the object when it might not be obvious. The quasar east of Arp 167 appears elongated north/south and not a point source. NED gives two SDSS designations for it, one labeled quasar (main one) and a second one labeled galaxy though the quasar designation is the default one. It's about the same distance as a much brighter galaxy so seems dim for a quasar. I've given it a Q label as that is NED's preferred designation. It looks more like a galaxy to me. Compare it to the far more distant but brighter quasar to the northwest of Arp 167 at nearly 11 billion light years.

There are two asteroids in the image. The bright one is just southeast of Arp 167 and is named (23153) Andrewnowell and is at an estimated magnitude 19.1. The dedication for its name reads: "Andrew John Nowell (b. 1988) was awarded first place in the 2007 Intel International Science and Engineering Fair for his electrical and mechanical engineering project. He attends the Nottingham High School, Nottingham, England." The other one is hiding in the north end of NGC 2677. It is (118611) 2000 GG143 shining at an estimated magnitude 20.0.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp167.jpeg

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

Related Designations for ARP167

ARP168

M32 is Number 168 in Arp's peculiar galaxy atlas. That puts it in his Galaxies (not classifiable as S or E): Diffuse counter-tails. How many times have you seen this companion to M31 yet not seen the counter-tail? Yeah, me neither. Arp's comment to this one: "Faint diffuse plume curved away from M31's disk." Odd Arp would consider it neither Elliptical or Spiral. Every source I checked classed it as a compact elliptical galaxy, most saying cE2. The "c" for compact. Most sources say much of its outer halo has been stripped away by the tidal forces of M32 yet the counter tail remains, albeit very faintly. If you blow up the image some of the stars of M32 are resolved around the left and bottom edges. At least I think they are members of M32 rather than M31. Blue M31 stars are seen along the right and top edges of M32 however.

To try and find this nearly invisible plume I exposed for several hours but skies were awful. Only 4 frames had decent seeing and halfway usable transparency. I didn't realize this at the time as I looked only at the first and last of the series and they looked good. But CCDSoft's auto histogram stretch can hide a lot. I didn't realize the first frame had 8 times the light throughput as the last. I ended up using only 4 of the series as that gave the best image. Including more just made the plume even harder to see. Note this was taken the day before my high-resolution C179 image and seeing was very good. Good enough to have binned 1x1 but I wanted the added speed of the 2x2 binning. That was a good choice as only 40 minutes of 1x1 binned data wouldn't have been as good due to added read noise. The color data was useless due to clouds so used the same low-resolution data I used for the previous C179 shot. It wasn't as bad of a match for this image so worked somewhat better.

In the raw data, M32 goes to the far lower left corner of the image. When stretched to bring this out the plume vanished into the background of M31. Probably why few are aware of its existence. Since this outer part of M31 is very blue but the plume from M31 rather red I dimmed down the blue parts of M31 in this area letting the redder features remain. This makes the plume visible though I'm not sure it is curving like Arp says. I don't see the curve on his image either. M32 was first seen by Guillaume Le Gentil on October 29, 1749.

Some of the same features on my close-up of M32 that I ran earlier are seen in this lower resolution image. Many other features beyond the edges of that image are seen as well so I've prepared an annotated image showing these as well. A few on the edges are shown on both but most objects already shown on my C179's annotated image are not included for the most part. Also, see that for details on the labeling scheme used.

G117 is a bit of a puzzle. It is on both Chart 5 and 6 of the atlas but the lines connect to different star-like objects! NED shows the lower and brighter one to be a globular so that is the one I chose to use. NED refers to it as SKHV 117. I put a ? by the other object as it has the PSF of an extended object, rather than a star. Just that it isn't in NED and only "half in" the Hodge atlas.

The image is full of open clusters. I've only identified a few of them. In one place I just put OC and ran lines to three in the area. Many fuzzy patches were not in the Hodge atlas nor NED. I gave up trying to track them down. I could spend months on this image alone. Just not worth it.

What I noticed most was the color of the globulars. Many appeared identical to orange stars but for their PSF not being starlike. Seems most globulars I image in our galaxy seem to have a slightly blue overall color thanks to the highly luminously blue stragglers. Are M31 globulars lacking in such stars, are we seeing them through lots of reddening dust? In any case, the tendency of neutral to orange color seems surprising to me.

There are many differences between NED and the Hodge atlas. For instance, the cluster C205 in the upper right corner is at the location of a very blue starlike object. NED shows no cluster at that point but does show the round emission object just below and left of it as a cluster. This whole region seems to be rather poorly mapped to RA/DEC coordinates. It made it impossible to really pin down which of the many HII regions in this area are which on my image. While NED says the position error is 5" on both axes I was finding nothing within that range. Even when I put those coordinates into the DSS it came up with nothing in that range either but maybe 10" away there was something that might be the object but go 10" another direction and there was another possible object. Move a couple minutes from the area and everything was fine again, I was agreeing within a tenth of a second of arc, not tens of seconds as I and the DSS were in this area. The round bubble below the bright star Hodge sees as a cluster is likely one of the Wolf Rayet bubbles listed by NED in the area. I just can't tell which one. In NED its position is nearly that of a cluster with the WR bubbles further away. I've given up, just enjoy the region. Blow up the image 2x for a better view.

To take out the bad taste left by the above fiasco scan down about halfway to the bottom on the right edge of my image and you'll find a small round red blob. That is listed by NED (coordinates match!) as a Super Nova Remnant they call MLA 0266. Looks like it would be grand as seen from a few thousand light years rather than a few million.

Arp's image, apparently with the Schmidt camera not 200" (at least his resolution is well below mine) and rotated so east is up rather than north is at:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp168.jpeg

14" LX200R @ f/10, L=4x10', RGB=4x10'x3 (same as used for C179 image), STL-11000XM, Paramount ME

Related Designations for ARP168

ARP169

Arp 169 is a trio of galaxies sharing a common envelope of stars, or at least they appear to. Redshift would put these at about 340 million light years. But studies using the D-sigma method which is often quite accurate when applied to elliptical galaxies put the distance much closer, say about 280 million light years. The group appears to be part of the ZWCl 2212.0+1326 galaxy cluster, a group of some 138 galaxies about 340 million light years distant. If so then the redshift distance to Arp 169 is probably correct. I suspect that the fact these are S0 galaxies and share a common halo has skewed the D-sigma calculation. Still, this galaxy cluster has galaxies with redshifts that match the D-sigma value as well. In any case its a ways from us. I've marked the approximate center of the cluster and its details on the annotated image. The center is just left of the annotation. Thus much of it is off the southwest portion of my image. It's size being 44' in radius fully covers my frame even this far off center.

Arp 169 is Arp's class: Galaxies (not classifiable as S or E) with diffuse counter tails. I see mostly a common envelope of stars, not a counter tail. I think Arp is referring to the somewhat north-northeast extension of the halo off the upper right galaxy NGC 7236. The middle galaxy is NGC 7237 with the small galaxy to the southeast being NGC 7237C/PGC 200377. Arp's comment; "Faint diffuse plumes coming away from two galaxies. 3C442." This would indicate he sees a plume from NGC 7237 or 7237C as well. I see a hint of one, maybe. The reference to 3C442 is because it seems to be coming from the core of NGC 7237 a radio galaxy also known as 3C442. This could be a sign they are actually interacting causing its black hole to be very well fed at the moment. While one source describes these as elliptical galaxies with no sign of recent star formation most describe all three as blue compact S0 galaxies. From the color of the halos in my image, I'd agree with the latter. The halo doesn't have the orange color most always seen with elliptical galaxies. Though there are some exceptions 3 in one spot would seem a bit too much of a coincidence to me anyway. The two NGC galaxies were discovered by Albert Marth on August 25, 1864. I measure the full extent of the halo that surrounds all 3 galaxies as about 250,000 light-years assuming a distance of 320,000,000 light-years.

While most galaxy clusters are populated with elliptical galaxies as their most common members this cluster seems to be mostly S0 galaxies. I don't recall seeing so many on one image before. One of the few exceptions is the face on, low surface brightness spiral south and a bit west of Arp 169. It is PGC 068368 a 15th magnitude galaxy. NED describes it as a Malin-like galaxy. These are usually huge low surface brightness galaxies but this one is only slightly larger than our galaxy at 125,000 light-years.

The annotated image shows all galaxies and quasars NED had redshift for. There's a very blue quasar at 8.4 light years right beside a galaxy that is quite likely far closer than the quasar. The most distant galaxy I know of in the image is about halfway toward the lower right corner. It is SDSS J221402.08+134424.9 at a magnitude of 21.1. It must be a big one for me to see it at a distance of 4,300,000,000 light-years. It anchors a group of 17 galaxies toward the lower right corner. The cluster's distance is by photographic spectroscopic methods (p) which gives only 4.04 billion light-years for the distance. The measurement of the galaxy itself is likely more accurate.

The rather bright asteroid is (88528) 2001 QU177 which is shining at about magnitude 17.4.

Arp's 200" image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp169.jpeg

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

Related Designations for ARP169

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