ARP301

ARP 301 is a pair of interacting galaxies in northwestern Leo about 300 million light-years distant. The two galaxies are UGC 6204 (face on spiral) and UGC 6207 the edge on spiral. Arp put them in is Double Galaxy class. Looks like it could have gone in his Wind Effects class to me. The plume on the east end of UGC 6207 that gives it that wind blown look doesn't have that appearance in Arp's image. Arp has no comment on this pair.

UGC 6204 is classed at NED as Sb? pec. Edge on UGC 6207 is classed as Sb? pec one place and SBb another. Arp made no comment on these. UGC 6204 does have three interesting knots in the arm that have been created by the interaction. The edge on also is full of blue knots. Wish we could see it from a better angle. UGC 6204 seems to have a double core. The SDSS sees the southwest (lower right) one as the main one apparently while everything else refers to the northeast one as listed at NED.

UGC 6207 has a blue knot just east (left) of the orange disk. The Sloan survey gives it a separate designation listing it as a separate galaxy. They give it a redshift that puts the object about 6 million light-years further away than UGC 6207. I really doubt that it really is a different object, however. There is a blue, maybe fuzzy, spot at the very end of the long tidal arm of UGC 6204 right where it begins to overlap UGC 6207. It's hard to tell from my image or Arp's if it is a star or star knot in UGC 6204. The Sloan image seems to show it is a knot. It doesn't list it in any way, either as a star or part of a galaxy. I will go out on a limb and say it is a knot below my resolution.

I've prepared an annotated image but many I'd like to have distance data on, have no redshift data at NED. There's a tight pair of apparently interacting red galaxies a bit over 8 minutes east of Arp 302. The western one with the plume is 2MASX J11103049+2416187 the one east and south of it is SDSS J111031.01+241612.9 but neither have redshift data. Further east and north is a galaxy with two wide faint spiral arms. It is 2MASX J11104138+2417298. North of it is KUG 1108+245. This catalog entry indicates it is an ultraviolet emitting galaxy. It is also known as the IR source 2MASX J11104153+2418248. So it is both an IR and UV emitting galaxy. This is interesting but again little more data is available for either of these galaxies.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp301.jpeg

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

Related Designations for ARP301

ARP302

ARP 302 is a pair of interacting galaxies known as UGC9618 located 460 million light-years away in the constellation of Bootes. Arp put it in his class: Group Character: Double Galaxies. Apparently, he missed the tidal star clouds around especially the northern member.

The southern galaxy is a Sc blue spiral. It shows some rather strong HII emission but isn't considered a starburst galaxy as it lacks the needed IR light. The northern member, however, is quite different. It is a red spiral classed at NED as Sb and is a LINER galaxy indicating its core is very active. It is classed as a starburst galaxy and does have strong IR emission showing active star formation. This is odd. Normally red spirals are considered dead spirals. Ones in which star formation has ceased so they are dying as all the new blue stars are long burned out leaving only yellow and red stars giving it a reddish hue. But here we have massive stars being formed though this is hidden to us by warm dust we see as IR light. I do note the very ends of its arms are blue. Usually, in a starburst galaxy, the majority of the star formation is in the core. These spirals are often barred spirals but this apparently isn't one of them.

While this field is covered by the Sloan survey NED shows no distances for any galaxies in the field beside the two making up Arp 302. Below Arp 302 is a tight trio of galaxies almost in a line. The two on the left look like one on the POSS plates but are separated by a narrow dark band in my image as well as the Sloan image. The right object is much bluer than the left but far smaller in angular size. Looks like a piece broken off the left piece but the color difference makes it obvious they are separate objects. I have no distance data so can't tell if they are really close together or not but at least NED does list them. The third member of the group just to their right isn't listed at NED but the faint 23rd magnitude galaxy beside it at the one o'clock position is. There are many interesting galaxies but about all I have on them is a magnitude estimate and their coordinates. Thus I didn't bother to prepare an annotated version.

I'd like to know more about the edge on spiral near the right edge of the image at the same level as Arp 302. It too is a red spiral and seems to have blue stars at the very ends of its arms. Coincidence? Or is it related to Arp 302 and had a run in with it in the distant past causing these blue ends? Wish I knew. There's just nothing much on these galaxies unfortunately Even Arp made no comment about them.

Normally I image at 1" per pixel binning the image 2x2. But this night seeing was far better than normal so I went to 0.5" per pixel by not binning. To keep the image size within reason for the internet I only downloaded the center one quarter of the image by area. When seeing permits I often enlarge the image to 0.67" per pixel. No need here as it already is at 0.5" per pixel. Still, the stars are very tight. Many only 1.2" to 1.4" FWHM. This is likely my highest resolution Arp image to date, slightly better than Arp 149 taken the previous night. But like the previous night, the good seeing didn't last. I'd hoped to take 12 L images but after only 7 seeing went very bad. So bad in fact I had to shut down. Color data was taken binned 2x2 the following night. I'd hoped I'd be able to get more L data that night but seeing was 2.5" (about normal) and far from what I needed to go to the 0.5" pixel. I never did get more luminance data. So the image is noisier than I'd like but the detail makes it worth it.

See Arp 177 for later and better images of this one.

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

14" LX200R @ f/10, L=7x10'x1, RGB=2x10, STL-11000XM, Paramount ME

Related Designations for ARP302

ARP303

Arp 303 is classed by Arp under Group Character: Double galaxies. He apparently made no notes on this one. Thus, other than there being two galaxies at the same distance, one of which appears a bit distorted I don't see that it is all that unusual. Many exist that to me are far more unusual that aren't in the catalog.

The southern, somewhat distorted galaxy, is IC 563. NED classes it SB(r)ab: pec. It does show a large dark area north of the core and a tidal arm to the west. The northern galaxy is IC 564 classed by NED as SA(s)cd? pec. Its peculiarity seems mostly due to a large radio loop. The pair is located in northwestern Sextans and are about 290 million light-years distant. According to the SDSS, the small blue knot in IC 564 to the southwest, just beyond a redder knot is really another galaxy, SDSS J094619.84+030406.6. They give no redshift data. I doubt it could be seen through the disk of IC 564 so is most likely a foreground object or really what it appears, a star cloud in IC 564. I vote for the latter as there's yet another such "galaxy" in IC 564 per the SDSS. It is a more yellow star cloud directly east of the core that is very small and nearly star-like except for its elongation. Usually these are noted as PofG by the SDSS indicating they are part of the galaxy or NED puts in a note to this effect. Neither happened here but I still am going to vote for them being part of the galaxy, maybe pieces digested from IC 563 when they were closer.

There are two other galaxies in the image that are at the same distance as Arp 303. They are close together to the northwest. The further, bigger and brighter one is IC 561. It is unclassed by NED but looks like a typical disk galaxy except for the two "holes" to the southeast and southwest. The other is, of course, the smaller spiral like galaxy to its southeast. It is SDSS J094602.21+030803.5 and is also not classed by NED. Again the CGCG catalog considers these a pair and records them as CGCG 035-049. Both were discovered by Stephane Javelle on March 21, 1893.

The large, low surface brightness galaxy toward the southwest corner of the image is UGC 5224. At only 100 million light-years it isn't related to Arp 303 but makes a nice addition to the image. It is also cataloged as CGCG 035-048 which considers it a triple galaxy with the blue and red galaxies toward its southeastern end. I find no redshift data but suspect this is just a chance alignment and they really aren't a physical triplet. To the northeast of the triplet as a nice oval galaxy with a large orange core surrounded by a slate blue disk. This is SDSS J094600.84+030141.1. Again I have no redshift data on it. Beside it to the east is the smaller blue galaxy, SDSS J094602.46+030140.3, at 940 million light-years. Why there's data on the fainter one only I don't know. Though it is unusual to see a blue galaxy at this distance.

At the top of the image almost directly above Arp 303 is a very red small galaxy. It is SDSS J094618.88+031417.9 at 1.52 billion light-years. To its east is what appears to be a group of very distant galaxies. While I find each listed in the SDSS none carry any distance data nor do I see a galaxy cluster listed for the area. To the southeast of SDSS J094618.88+031417.9 is SDSS J094618.88+031417.9. It is listed as being 930 million light-years distant. Go directly east from this galaxy some distance and you come to two equally bright blue stars of 15th magnitude. Continue east to the first much fainter orange star. Go southeast to another slightly fainter orange star. Continuing an equal distance brings you to a blue star of about 20th magnitude. This is the most distant object in the image that I'm aware of. It is the quasar SDSS J094649.38+031152.7 with a redshift of z=2.059650. This would put it about 10.5 billion light-years distant. The light was leaving it about the time our galaxy was born and 6 billion years before our sun was created.

Well left of center and a bit south are two 20th magnitude elliptical galaxies that seem in the core of a bunch of much smaller and fainter galaxies. Large galaxies often anchor galaxy clusters. Is that what's happening here? I see no cluster listed. They are SDSS J094702.91+030023.8 and SDSS J094704.71+030024.0. Redshift puts them about 3.6 billion light-years away. None of the smaller, fainter galaxies in the area have redshift data that I could find.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp303.jpeg

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

Related Designations for ARP303

ARP304

Arp 304 consists of two galaxies NGC 1241 and NGC 1242, right to left and a double star to the southeast, NGC 1243. The two galaxies were first seen by William Herschel. John Herschel, unable to see 1242 recorded the double star. Dreyer saw all three but recorded the double star as a nebula. It seems odd that even with a 72" scope (speculum mirror I assume) he couldn't recognize 2 14th magnitude stars 12" apart. The NGC is full of such mistakes, some single stars. They are the two stars southeast of NGC 1242. William Herschel found NGC 1242 on January 10, 1785 and NGC 1243 on December 15, 1786. Neither are in a Herschel 400 observing program.

The pair is about 175 to 178 million light years distant in the constellation of Eridanus. Arp put them in his catalog under double galaxies with filaments. I suppose that is the northward arm of NGC 1241. While red shift puts them at about the same distance there's some question about whether they are interacting or not. One note at NED says no, another yes and another wanted more data. NED classes NGC 1241 as SB(rs)b Sy2, NGC 1242 as SB(rs)c:. NGC 1241 does have that odd arm and NGC 1242 seems odd with that very blue northern arm and one heavy arm. So I vote for the interaction being possible. Still, there are no real plumes which is likely why others say no interaction.

The field is out of the Sloan Survey coverage. Only one other galaxy in my field has a known redshift. To find it look well east (left) and a bit south (down) of Arp 304. It is the largest red round galaxy. Further east is a close rather bright double star with a blue galaxy above it. The red one is 2MASX J03121399-0858394 at 1.3 billion light years. The blue one is APMUKS(BJ) B030959.78-090917.2. Other than it being magnitude 18.15 there's no data on it or any other galaxy in the image.

But there is one asteroid 2005 LZ45 at magnitude 19.8 shows up as a short streak angling slightly upward west of the bottom end of NGC 1241. It is at the edge of the 150% crop image above a slightly orange star that's the first up from the bottom right corner of the cropped image.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp304.jpeg

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

Related Designations for ARP304

ARP305

ARP 305 is a pair of galaxies. That's how Arp classified them as well, "Group Character: Double Galaxies. This is the same classification as Arp 303 though this pair is far more interesting. The northern galaxy is NGC 4016. It looks to me as if it has two sets of spiral arms. One set narrow and looping back to the core like a pretzel while the other pair are broad and set at nearly a right angle to the first pair. Both are obviously due to tidal effects of a close encounter, probably with NGC 4017. But explaining their vast difference would seem to me to be a major headache. Could it be two merged or superimposed galaxies? If so, rotational rates would likely be different but since we see it so face on, likely not enough different to be measurable. NGC 4016 is classed by NED as SBdm:. Train-wreck is likely a better classification. One note at NED says of it: "Distorted, patchy, hints of spiral structure in the outskirts". Odd but I thought those arms were rather obvious. Why it isn't classed as peculiar as well I can't fathom. NGC project though does class it SBc-Irr which makes more sense to me.

NGC 4017, while at first appearing more "normal" shows strong signs of interaction with NGC 4016, not the least of which is the faint connection that seems to run from its northern arm up to NGC 4016. Most obvious is the debris almost dead center between them. It seems a bit "windswept" (to use an Arp term) with wisps of stars appearing to have been "blown" northwestward. Arp commented on this filament when he said: "Segment breaking from arm of small galaxy, weak filaments reach to north galaxy, which has figure 8 loops." The detached piece plus the faint piece half way between almost make it look like the northern arm of NGC 4017 is shooting star blobs at its companion. Note too that there's a lot of debris off the southern arm as well that heads nearly due east. I've attached a 150% enlargement of my image that shows this a bit better than the main image. I suppose any residents living on stars orbiting these detached pieces would resent being called debris. NGC 4016 was discovered by R. J. Mitchell on March 30, 1854 while NGC 4017 was seen by William Herschel on April 11, 1785. It isn't in either H400 observing program.

The pair are located about 170 million light-years from us. NGC 4016 is located about 2/3rds of a degree south of the southern border of Ursa Major only a few seconds of arc into Coma Berenices from Leo. About 10 minutes of arc north of my image is the center of the NGC 4008 group. This group is listed in NED to be about 170 million light-years distant. It is likely Arp 305 is part of the group. Not far from its center is NGC 4004 which is also highly distorted and on my list for next spring. It too is 170 million light-years away and may have tangled with Arp 305.

The galaxy northwest of NGC 4016 is MAPS-NGP O_320_0562408. Its redshift indicates a distance of only 40 million light-years. If so, it is a dwarf irregular galaxy.

Well below NGC 4016 and southwest of NGC 4017 is a small lenticular like, very red galaxy. It is SDSS J115824.86+272340.4 at just under 2 billion light-years. West of it is a blue star, angle up a bit from it toward the very bright blue star, about one third of the way you come to a smaller reddish galaxy, it too is 2 billion light-years away. It is not an IR galaxy like the previous one was and not as red. It is SDSS J115808.00+272428.4.

Southeast of NGC 4017 are two short dashes with a gap between them. This is the asteroid (84842) 2003 AS17 at magnitude 19.1. I took color data between two 20 minute luminosity imaging runs. That created the gap as there's nothing for the color data to color in the gap. Below the western end of the western trail is a very red spherical galaxy. It is SDSS J115903.15+272321.9 and is also just under 2 billion light-years from us. There are quite a few other galaxies in the lower part of the frame that are at this 2 billion light year distance. 2 minutes of arc below the south edge of the image almost on its centerline is the galaxy cluster MaxBCG J179.60472+27.27528 with 22 members per NED. Its distance is listed as, you guessed it, just under 2 billion light-years. With no size given for it, I can't tell if the 2 billion light-years distant galaxies in my image are part of the group or not. It seems likely, however.

The fuzzy galaxy in the lower right corner is MAPS-NGP O_320_0562408.

SDSS image
http://astronomerica.awardspace.com/SDSS-30/NGC4016.php
http://astronomerica.awardspace.com/SDSS-30/NGC4017.php

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp305.jpeg

14" LX200R @ f/10, L=4X10' RGB=2X10', STL-11000XM, Paramount ME

Related Designations for ARP305

ARP306

ARP 306 is classed by Arp under his double galaxy class. It is located in Pisces. Arp's comment: "Diffuse, hooked countertail." NED considers this a double double galaxy much like Epsilon Lyrae is a double double star. Each of the main galaxies is listed by NED as being a merging galaxy pair.

The larger galaxy pair is UGC 1102. The lower part is UGC 1102 NED01 at 76 million light-years while the main part of the galaxy is UGC 1102 NED02 with a redshift distance of 74 million light-years. This is the object he refers to in his comment. The "hooked countertail" comes off its north end. When giving the position of Arp 306 Arp used the coordinates of this pair rather than a position between both pairs.

The smaller and fainter pair to the northeast is UGC 1105 with a redshift distance of 79 million light-years. It doesn't have a redshift for each part only one for the pair. UGC 1105 NED01 is the very blue near starlike object toward the northern end of the galaxies core region. The lower, ill-defined part is UGC 1105 NED02. NED's position for the southern part is about the middle of the object where there is a faint, double, condensation rather than the lower, bigger and brighter condensation (all three appear about equal in the SDSS image, however. The lower one wasn't listed which surprised me. The only redshift value given is for the pair.

Did Arp realize this was two pairs of interacting galaxies? If he did he never mentioned it. Though he had little to say about any of his entries, letting the category speak for itself. What comments he did make added little to understanding the object, being only descriptive in nature.

The only other object in the image with a redshift measurement is the galaxy cluster NSCS J013202+044446 to the northwest of Arp 306. It is listed at NED as having 20 members and a redshift distance of about 4.8 billion light years. No diameter is given so how many of the very faint galaxies in this area are members I can't say.

This image contains more asteroid trails than I've ever captured on one image. The L channel was taken over two nights which helps in the capture of so many. 5 came from the first night under rather poor conditions while the other 11 were seen the second night. Four were in both images. Rather than 16 asteroids I actually captured 12, 4 of them twice. Color data came from the second night. So only "bright" asteroids from that night show a color trail.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp306.jpeg

14" LX200R @ f/10, L=8x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP306

ARP307

ARP 307 falls under his class: Group Character: Group of Galaxies. It is located in Leo with has more than its share of galaxy groups. Arp's comment: "Possibly not interacting." It consists of three galaxies, NGC 2872, NGC 2873 and NGC 2874. Not exactly right to left. NGC 2872 is the big E2 elliptical. Redshift data puts it at about 160 million light years distant. NGC 2873 is also about 160 million light-years distant by redshift. NED doesn't give a Classification. The NGC Project says Sb which seems reasonable. It certainly is a red spiral, a new class of galaxy to come out of the Galaxy Zoo project. This leaves the big barred spiral, NGC 2874, also a red spiral or maybe a normal spiral in the process of turning red as most new star formation has apparently long ceased with the massive blue stars long dead but some slightly blue ones left in a few knots. Classed at NED as SB(r)bc and questionably (to me) as Sc by the NGC Project. It seems a very obvious barred spiral. Though the Hubble Space Telescope image makes the bar less obvious. Redshift data puts it at 180 million light years distant. This could be due to random motions in the group or could really mean it is unrelated. I lean toward it being part of the group as there appears to be a hint of interaction at the southwest end.

There are two other nearby NGC objects. NGC 2871 is just a blue star at the north end of NGC 2872. This type error is rather common in the NGC. Things get a bit more interesting with NGC 2875. I find two positions and two identities suggested for it. Both are shown in the annotated image. There's no question this object is in the northeastern part of NGC 2874. NED's description and position point right to knots in the northeastern arm. The NGC project, however, points to an area just above two apparent stars where the galaxy is rather dim. But gives almost exactly the same position as NED. Then says "This is the north-following part of NGC 2874. Lord Rosse's micrometrically measured offsets point exactly at the rather knotty spiral arm, and his description is consistent with the appearance on the Sky Survey (DSS 1)." This seems to describe the arm NED points to but their diagram points where I show it in the annotated image. Most likely their diagram is wrong.

NGC 2872 and 3874 were discovered by William Herschel on March 15, 1784. They didn't make either H400 observing program. NGC 3873 was found by R. J. Mitchell on February 22, 1857. Lawrence Parsons is responsible for NGC 2875 on March 7, 1874.

A couple notes about the annotated image. Two faint galaxy clusters are anchored by a cD galaxy. These are noted by G/CG with the distance shown being that of the cD galaxy. At bottom center, there's an object that NED lists in some catalogs as a galaxy with an AGN and others call a Quasar. It is marked G/Q for that reason. Labels are immediately west of the object unless that would cover up some other object. In those cases, a line points to the object.

There are 5 asteroids in the image. They are labeled in the annotated image. Here's the list in order of closest to furthest from the center of the image. Magnitudes are estimates of the Minor Planet Center. These aren't always very accurate. Note that Burkam is listed as at more than a magnitude brighter than the rest but appears dimmer than the brightest. Some of this may be due to the lack of red sensitivity in my sensor.

(155041) 2005 QZ172 19.8
(158647) 2003 DL2 18.7
(14570) Burkam 17.3
(97481) 2000 CF61 18.2
(121727) 1999 XQ155 18.7

Naming citation for Burkam:
"Ann Burkam mentored a finalist in the 2002 Discovery Channel Youth Science Challenge (DCYSC), a middle school science competition. She teaches at the Buckeye Valley Middle School, Delaware, Ohio."

When taking this object the first blue frame was dimmed by clouds. The following night I took two more blue frames. I seemed to get better color including the first blue than I did not using it so this is why there are 3 blue frames and only 2 of the other colors.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp307.jpeg

Sloan image:
http://astronomerica.awardspace.com/SDSS-19/NGC2872-4.php

Black and white HST image
http://upload.wikimedia.org/wikipedia/commons/c/cf/ARP307-NGC2872-NGC2874-HST-702.jpg

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

Related Designations for ARP307

ARP308

Arp 308 is a pair of galaxies; NGC 545 and NGC 547 that is associated with the radio source 3C40. That is NGC 547 is considered to be the source of 3C40. Arp put the pair in his category of simply double galaxies. His simple remark says: "Close ellipticals." which isn't very informative. NGC 545 to the north is listed as an SA0 galaxy while NGC 547 is E1 and a bright cluster galaxy. Redshift puts it at 6 million light-years further from us that NGC 545. However, NED gives a D-Sigma distance determination that is the same for both. Likely the difference in radial velocity is due to relative motion rather than distance. The exact same D-Sigma distance is found for NGC 541 (Arp 133) as well. A 1964 paper concludes NGC 545 is not interacting with NGC 547. I find that hard to accept.

Notes about the annotated image.
Objects considered part of Abell 194 are listed by name.

Redshift distance using NED's 5 year WMAP assumptions are used. They are expressed in billions of light-years. Differences in cluster member radial velocity are most likely due to relative velocity around the cluster's center of mass rather than a true distance indicator. Most, likely lie within a few million light-years of each other. The label is immediately right of the object when possible. Otherwise, a line will connect the object and its label.

XMMU J012535.9-012546 is an X-ray galaxy. It appears to be a very compact dwarf of some sort.

ARK 45: A note at NED says "Together with NGC 0547 this is the radio source 3C 40." I'm not sure how this was determined, especially since NGC 545 is in the middle yet not considered part of 3C 40 that I found. Also, note its redshift is surprisingly different.

NSCS J012537-011739 is a galaxy cluster at 4.97 billion light-years. It contains 36 members. The diameter isn't specified. I see a dozen or two within a few minutes of the center. Many look like faint stars.

WHL J012538.1-011301 is another galaxy cluster at 5.3 billion light-years. It contains only 8 members. Its center is a couple seconds of arc from a faint galaxy, probably the anchoring member. The NED position is only approximate so likely means to point to this galaxy.

The UvES (Ultraviolet Excess Source) is likely a quasar given its distance.

Arp's image of these galaxies is made from the same plate and cropped to exclude the other atlas entry. Most of his images are shorter than the one hour exposure on 103a-0 image. The added time is likely due to losses in the "Polaroid" filter. He lists the seeing as average 1" to 1.5".

NGC 535 and 543 were discovered by Heinrich d'Arrest on October 31, 1864.
NGC 541 was discovered by Heinrich d'Arrest on October 30, 1864.
NGC 545 and 547 were discovered by William Herschel on October 1, 1785. It isn't in either Herschel 400 observing program.
NGC 548 was discovered by George Searle on November 2, 1867.

Arp's image of Arp 308
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp308.jpeg

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

Related Designations for ARP308

ARP309

ARP 309 is made up of two interacting galaxies, NGC 942 (lower) and NGC 943 (upper). The pair is located in Cetus about 200 million light-years distant. They are the largest two of a group of galaxies known as the USGC S088 group. NED lists it as having 8 members. While they are not identified there are 8 galaxies with known redshift values which indicate they are at the same distance as Arp 309. Since no other galaxies in my field have redshift values I've not labeled any but those probably in the group.

Arp put #309 in his class for double galaxies. Arp apparently missed or wasn't interested in the large plume going north from NGC 943 or the smaller one going south from NGC 942. His only comment addresses the very red dust ring in NGC 943 when he says: "Peculiar absorption ring, possibly broken." Both were discovered by Frank Muller sometime in 1886. The exact date is unknown.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp309.jpeg

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

Rick

Related Designations for ARP309

ARP310

ARP 310 and 311 is an odd combination in Arp's catalog. Arp 310 consists of IC 1259, a close pair of galaxies. Arp 311 consists of Arp 310 and adds IC 1258 to its southwest and IC 1260 to its southeast. Arp 310 is classed under Group Character: Galaxy pairs while 311 is under Group Character: Galaxy Groups. There are other galaxies in the area but as far as I can determine they aren't included in 311 by Arp. Arp 311 is also known as WBL 640 and is listed by NED as consisting of only 4 galaxies. But the SDSS lists a cluster centered on Arp 310 called SDSS-C4-DR3 3143 consisting of 47 members. It puts the average redshift for the group at 8394 km/s while that of Arp 310 is a bit less at 8100 km/s. The difference is insignificant as relative motion within a cluster can easily exceed this difference. So apparently the group is much larger than Arp realized. Using this latter redshift the distance to Arp 310-311 would be about 375 million light-years. Arp's comment on Arp 310 was simple that it consisted of two close elliptical galaxies. He had nothing to say about Arp 311. These galaxies are located near the head of Draco, just east of the Draco Dwarf Galaxy, a satellite galaxy of our Milky Way Galaxy that is one of the dimmest galaxies known consisting mostly of "dark matter" and a handful of stars.

Arp 310's two galaxies are classed as S? (right) and S0 pec (left) by NED. This disagrees with Arp's elliptical statement but does agree with my image that shows them as having a somewhat bluer cores than the outer halo. Most ellipticals have a far redder core than these do. IC 1258 is classed by NED as Sab? I'd put a pec on that. It does appear to have somewhat blue arms but this is an illusion. Looking at the three color planes red is slightly stronger than blue yet it appears blue to my eye when compared to the red of the nearby galaxies and its own core. My image seems to show a bridge of red stars between the two galaxies. As best as I can tell Arp usually used a blue sensitive film with a yellow filter to take most of his images. This won't pick up a bridge of red stars very well but I think I see a hint of it in his image when shrunk down. Odd he never commented on it.

There's a lot going on in the image. I've prepared an annotated image. Galaxies in the SDSS-C4-DR3 3142 cluster beside those of Arp 310 are listed by name with no distance while those far beyond the cluster are listed by distance. Quasars are also listed by distance. One is very near Arp 310. Something Arp considered meaningful rather than a coincidence nearly all other astronomers agree it is.

In the annotated image note the two very close quasars in the lower right corner, both of which have virtually the same redshift showing a distance of 8.7 light-years. The redshift of the one on the left is z=1.269000 while the left is z=1.269040. I find nothing to indicate they are the product of gravitational lensing. Their colors are not the same, the left one has far more blue in it. Two quasars this close, 7 seconds of arc, is rather unusual I'd think. I'm only guessing here.

Arp's images:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp310.jpeg
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp311.jpeg

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

Related Designations for ARP310