ARP257

Arp 257 is a double galaxy in Hydra about 170 million light years distant. Arp classed it in his category, Galaxies (not classifiable as E or S): Irregular clumps. for once I can sort of agree on the not classifiable as E or S part. I'm not sure what the clumps are he speaks of. Likely it is the two blue blobs leading from the lower galaxy to the upper. Arp's comment reads; "Galaxies joined by segment of thin arc."

Both galaxies are cataloged as UGC 4638. But they do carry separate entries in the MGC catalog. The southern being MGC +00-23-005 which is described as a disrupted spiral (?) with a chaotic outer disk, main body 0.8' x 0.5'. NED classes it as S pec. The upper galaxy is MGC +00-23-006. NED says of its classification "spiral ?"

The blue color of both would indicate spiral or irregular and certainly indicates massive star formation is currently going on in both due to their tidal interaction. SIMBAD considers the larger of the two other galaxies to be "Part of Galaxy" and gives it the designation VV 041c. VV 041a and b are the two galaxies Arp considered as Arp 257. Is it part of the upper or lower galaxy? Looks rather like a separate galaxy to me. What about the fourth galaxy? Wish I knew. Neither NED nor SIMBAD mention it. The blue galaxy north of the Arp 257 group near a bright star is anonymous. To the west of Arp 257, nearly 9.5' away, is 6dF J0851002-022201 and is only half the distance of Arp 257 at about 85 million light years. There are no other galaxies with a distance estimate that I could find. This region is rather obscured by our galaxy's dust. For that reason, it has been little studied. Sloan stays away from such regions so hasn't covered it nor is it likely to in a future survey.

I didn't check around my field of view. I wish I had as just out of the image at the top is UGC 04640 a much larger galaxy than those of Arp 257 but at the same distance. In fact, the redshift is virtually identical so it is likely related. I usually check for such things before taking the image but didn't this time -- the one time I should have.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp257.jpeg

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

Related Designations for ARP257

ARP258

Exactly what constitutes Arp 258 is a bit difficult to determine. Some sources are quite inconsistent from page to page in this regard. Some say it is just the chain of debris plus one galaxy at the bottom all collectively known as Hickson 18 or UGC 2140. Others leave off the bottom galaxy as it is a distant interloper. One that leaves off the bottom one on one page includes it on another and adds the two anonymous galaxies to the west. So take your pick.

The upper string carries three entries in the PGC/LEDA catalog 10042, 10043 and 10044 top to bottom. The top two are blue, 10044 is more orange. The redder galaxy below this is 10046 in that catalog. The first three have a redshift indicating a distance of about 175 million light-years while the bottom one shows the much greater distance of 445 million light-years. Way too big of a difference to be considered part of the group. While the upper part carries 3 PGC numbers it is made up of a lot more pieces. Some papers say there are 6 galaxies in this group. I could argue for even more as the upper part alone has 7 bright condensations. The lower part is drawn out into two longer pieces or is it just one piece darker in the center? Then there's the debris cloud that is spread across the whole mess. I can find no data on the two galaxies to the east. They, like PGC 10046 appear unrelated to the smash-up. One is a near starlike elliptical and the other an S0 galaxy. PGC 10046 is classed as SB0. Arp's comment on the blue parts: "Resolution into knots on larger galaxy." Or is he referring to the two parts of the somewhat orange one that's so torn apart? I don't know.

PGC 10042 is listed as Im. Exactly how much of the upper part of this mess it is considered to be is hard to tell. Its dimensions of .6 to .7 minutes covers most of the northern pieces, 6 in all.

PGC 10043 seems to consist of the northern part of the elongated double southern half. It too is classed as Im but is shown as .7 by .4 minutes which must include some of the debris cloud.

PGC 10044 is another mystery. NED considers it the entire group of 3 galaxies while most other sources consider it the bottom part of the three. In any case, the bottom part is also classed as Im. Likely because they had no idea what the heck is going on here.

Something has certainly disrupted whatever this was before the encounter. So there were at least two objects here. We now see many pieces. Likely they will combine to form one elliptical galaxy in the future. But for now, it's one big mess. I couldn't find many papers trying to straighten it all out either. A couple however referred to it as two disrupted galaxies, another a faint spiral and fragments and yet another as 6 galaxies. Based on the color in my image, it appears the 2 galaxy idea might be right as one is somewhat blue while the other reddish. To me, the scientific name for that type of agreement is to call it a mess. Though it deserves an adjective I can't use here.

The galaxy to the SE of the group is 2MASX J02393096+1819089 ID Other than it being an IR emitting galaxy in the 2 micron IR survey I have little on it. The same applies to the smaller galaxy to its southwest. While a few other IR galaxies are in the field none have much information other than position. At least I can identify the 3 asteroids in the image!

ASTEROIDS
(36784) 2000 SU11 18.9 Upper right from Arp 258
(68306) 2001 FU103 19.6 near left edge a bit north of 258
(718) Erida 15.9 Below 2001 FU102, nearly starlike, bright, below two stars of similar brightness forming an equilateral triangle. It is slightly reddish in color which surprised me. I must have caught it a the end of its retrograde loop when it was nearly stationary in the sky.

Directly east of Arp 258 is what appears to be another asteroid. It isn't one. I suspect it is a distant edge on galaxy. It just barely shows in the POSS two plates. This isn't an area covered by the SDSS survey. It is too faint for other surveys so, for now, is anonymous.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp258.jpeg

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

Related Designations for ARP258

ARP259

Arp 259/NGC 1741/Hickson 31 is a tight group of galaxies about 180 million light-years away in the constellation of Eridanus just north of the Witch's Head Nebula (far too large for me to try imaging). Arp put it in his category Galaxies (not classifiable as S or E): Irregular clumps. His comment reads: "Material extends SE toward peculiar round spiral." That is IC 399 which is also the G member of Hickson 31. NGC 1741 was discovered by Édouard Stephan on January 6, 1878. IC 399 was discovered by Rudolf Spitaler on February 25, 1892.

Hickson considered this to be at least 6 galaxies, A-F but some put IC 399 in as G. NED includes many more. I've shown most of them on the annotated image but in a couple cases, the positions had a 5" error circle making it hard to tell which was which. In one case H1 and H2, I gave up and drew one point for both. Others I saw nothing in the circle so didn't include. Most had redshift distance. All but one of which put it at about 180 million to 185 million light-years. One Hickson 31D was very red in color, often a sign of distance due to interstellar reddening. Sure enough, it is 1.2 billion light-years distant and obviously just a bright line of sight galaxy far larger than any in the true group. Some members of Hickson 31 are considered part of NGC 1741, parts A, B, C, and D. Though again, D is obviously only a line of sight member.

It appears to me that many of the other members NED includes are really just massive star formation regions created out of the debris of the interaction of A, B, C and possibly E. G is certainly a separate galaxy. F could go either way but I prefer it a small dwarf with massive star formation creating the strong IR light it emits.

Then there is the one that NED labels as Q! I have no idea what happened to all the rest between G and Q. It's only other catalog name I could find is NPM1G -04.0219. Since this field is out of the SDSS survey only a few galaxies in my image are cataloged. Just yesterday, as I type this the Sloan 3 data was released. It covers some other areas of the sky besides that of previous Sloan surveys but I don't think this field qualifies. Still, I wanted to check but the website seems to have new site jitters and refused to do anything when I entered this field. Just timed out doing nothing. Fields I knew were in the survey did load so apparently, that is its way of telling me I was out of bounds as I expected.

The annotated image gets a bit busy trying to point to all the pieces NED records with the HCG31 label. To save space I left that part off and only included the suffix, add HCG31 to all. Most had redshift data. A few of the faint pieces didn't. I didn't distinguish those. Only D is noted with redshift distance since it was obviously a line of sight member. Other galaxies not considered members by NED are labeled only with their redshift distance using 5 year WMAP data and the time travel distance. Many galaxies, including the large low surface brightness one NE of Arp 259 weren't in NED at all. Very frustrating but it wasn't an IR strong galaxy so not picked up by the 2 micron survey which most of the field relies on.

The below chart listS the catalog designation of the members of this group.

NGC 1741A HCG 31A Sdm 186
NGC 1741B HCG 31B SB(s)m pec 189
PGC 16573 HCG 31C SB(s)m pec 184
PGC 16571 HCG 31D Sbc 1169 Obviously not a member
HCG 31E no class 183
GALEX 2732886767084503642 HCG 31F 181
IC 399 HCG 31G IAB(s)m pec 182
HCG 031Q 187

All are between 181 and 189 million light-years distant by redshift.

Hubble Space Telescope image of A-E, north sort of up It's a "little" better than my image for some reason.
http://upload.wikimedia.org/wikipedia/commons/0/05/HCG_31_HST.jpg

Arp's image oriented west up rather than north up as mine is
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp259.jpeg

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

Related Designations for ARP259

ARP260

Arp 260/UGC 7230 is a pair of interacting galaxies in southwest Coma Berenices a bit north of M98. They are thought to be about 340 million light-years distant. Arp put them in his classification Galaxies (not classifiable as S or E): Irregular Clumps. I suppose that refers to the two star clusters north of the core of the western (right) member. His comment on it reads: "Possible lines of faint condensations extending south." Does this refer to the large southern plume from the western member? The attached Sloan image seems to break it up into linear features.

The pair is listed in many catalogs as a pair. I didn't find a separate designation for them. So they are known as UGC 7230 or MCG +03-31-077 or KPG 326 etc.

NED classes both members as Sc. I'd think they both are worth a pec. designation but apparently NED doesn't agree. The western part of the two star clusters north of the core of the western member does have its own entry in the Sloan catalog, SDSS J121337.45+160718.0. Though it is marked at NED as being part of the galaxy, not a separate galaxy.

Arp 260 is a member of a group of galaxies at about 340 to 360 million light-years years by redshift. The actual distance is probably closer to 350 million light-years averaging out their redshifts. All are marked on the annotated image that are in NED. Several are very blue like Arp 260 though far smaller. Something has happened to trigger all that star formation. Group members include the more ordinary spiral CGCG 098-102 at the upper right. I'm rather puzzled that it is classed as SA0. I'd think SAb would be more reasonable. It has one somewhat blue arm but otherwise is a pretty old star looking spiral. The other old star looking galaxy is VCC 0075 west and a bit south of Arp 260. It looks rather like an elliptical galaxy but NED shows it as S0? If so it must be seen end on to be so elliptical looking. At the very bottom is a blue member of the group LEDA 1497645, also known as AGC 226038 and ALFALFA 1-171. No, it's not a member of the Our Gang movie series. ALFALFA stands for Arecibo Legacy Fast Arecibo L-band Feed Array. Someone was having acronym fun it would seem. In any case, it is obviously a strong radio source. AGC stands for Arecibo General Catalog so that scope put it in two of its catalogs. I couldn't find anything at NED on it, however. Must be a lot going on there, however. It's strong blue color would also indicate lots of new stars being created there.

NED shows a galaxy cluster at 2.7 billion light-years, MaxBCG J183.37186+16.06813. They show it as having 16 members. The center of the cluster is at the position of a very red galaxy southwest of Arp 260. The galaxy is 2MASX J12132924+1604054 and has a redshift showing it to be 2.7 billion light-years distant. The cluster has a photographic redshift distance of 2.6 billion light-years. I've noted it on the annotated image as G/GC with both distances shown. I don't know if the smaller red galaxy just east of the marked one is a member of the group. I suspect it is but NED doesn't give me enough information to be certain of this. There are several galaxies at the 2.7 billion light-year distance in the image. I assume they are members of this group. No angular size is shown for it.

There are some galaxies I'd like to know more about. The large, but faint blue galaxy at bottom center is SDSS J121411.39+155759.5. I have no distance data on it or anything else of much use to tell how it might fit with anything in the field. The Sky shows it as PGC 39076 and classes it as S?. I don't see any hint of spiral structure but my exposure time didn't collect much to go on. It is blue like many spirals but that isn't sufficient to call it a spiral.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp260.jpeg

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

Related Designations for ARP260

ARP261

Arp 261 is one of the stranger entries in his atlas. It consists of several galaxies and or star clouds located in the constellation of Libra a bit under 100 million light-years away. This one is rather low at -10 degrees and was down in the gunk when I imaged it. This reduced my resolution and depth. I tried to compensate with more luminance images but this low the time available is limited. Only one extra frame was usable. Following nights were worse so I just gave up and went with the 5 I had.

Arp put it in his class Galaxies (not classifiable as S or E): Irregular Clumps. He did leave a comment on this one, "Some condensations resolved, similar smaller galaxy appears north." That galaxy is the irregular galaxy PGC 052943 also about the same distance from us by redshift measurement.

How many galaxies are involved with Arp 261 depends on which catalog you check. It consists of two main galaxies. The biggest is to the southwest (lower left) of center. It is Arp 261 NED01/VV140a/MCG-2-38-016/PGC 52940 as well as many other catalog entries. NED classes it as IB(s)m pec. The other main part to the northeast is Arp 261 NED04/VV140b/MCG-2-38-017/PGC 52935. It too has other catalog entries but not as many as the southwestern part. It too is classed by NED as IB(s)m pec. Notes at NED though seem to consider these two highly distorted spirals with interconnecting, tangled arms at the northwestern end. This doesn't explain the connection between the middle parts of both, however. Two catalogs list the two small condensations to the east (left) of the bottom end of the largest galaxy as separate galaxies. The lower is Arp 261 NED03/VV140d while the fainter upper one is Arp 261 NED02/VV140c. Neither are classified or have redshift data. I see them as star clouds likely created by the interaction of the two main galaxies. That's just my speculation. I have a tough time seeing them as separate galaxies.

The galaxy near the left edge of my image about level with PGC 052943 is 2MASX J14503533-1005202. The Sloan survey doesn't cover this part of the sky. Like all the others in the field, it has no redshift data.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp261.jpeg

14" LX200R @ f/10, L=5x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP261

ARP262

Arp 262 is two superimposed galaxies. It is also known as UGC 12856 among other catalog entries. Arp classed it under "Galaxies not classifiable as S(piral) or E(lliptical); Irregular clumps. It turns out those irregular clumps in the southern end are actually another galaxy. Based on redshift the main galaxy is 65 million light years away and the companion 88 million light-years away. All that really tells us, however, is that the blue companion is moving away from us 28% faster than the main galaxy. If they are really interacting wildly differing red shift speeds can occur at the same distance as the "fall" into each other. They are located in the southeast corner of the Great Square of Pegasus. Pegasus is a place lots of distant galaxies are usually seen. But this field is oddly missing the great number of faint background galaxies I'd expect to see. NED only lists 3 galaxies within an area larger than my field of view besides the two making up Arp 262. At least I see more than that! From my search of the literature, there is very little known about this object. Arp's comment on this one is: "Some resolution into knots." For now, I'm going to say these are just two line of sight galaxies that are unrelated.

Due to clouds, I got only limited data. Two luminance frames were severely hurt by clouds and only one color image was usable for each color. I'm surprised it came out as well as it did.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp262.jpeg

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

Related Designations for ARP262

ARP263

ARP 263/NGC 3239 is thought to be the merger of two galaxies. It was discovered by William Herschel on March 21, 1784. It failed to make either of the Herschel 400 observing programs. I find no records that I ever viewed this one visually. When displayed with south up it looks much like the Minnesota state bird, the loon. Though it has a spike for a tail a loon doesn't have. The spike is likely a trail left by one of the merging galaxies. The head is likely the trail of the other merging galaxies. I suspect the spike tail is straight only from our viewpoint. Seen from the "side" I expect it to is curved. The head trail has superimposed on it a red star at just about the spot the loon has a red eye. It also has a white neckband right where two bright star-forming regions and the supernova make a bright area. I've included a picture of a loon family for those unfamiliar with this large diving bird (it is not a duck) that can dive over 200 feet deep and has solid rather than hollow bones. Being so heavy it needs a lot of runway to get airborne and gains altitude very slowly. When I imaged in on January 21, 2012 it contained a supernova that I've marked in the annotated image. Its resemblance to the loon is best seen when displayed south up rather than my usual north up orientation.

SN2012a was discovered by amateur astronomers on January 7th. It was the first supernova of the year. It is a type II supernova meaning it is a single massive star that lived fast and died in a blaze of glory we are just now seeing millions of years later. The redshift distance to the galaxy is 50 million light-years but most think it closer though, to be consistent, I used the 50 million light-year figure on the annotated image. Most current estimates are more like 25 to 30 million light-years. The one Tully-Fisher measurement at NED says 26 million light-years. In any case, it is a rather small galaxy, likely the result of a merger of two even smaller galaxies. NED classes it as IB(s)m pec. It has two tidal tails. A straight one on the west side going south-southeast that is full of knots of star formation. The other tail is a smooth curving one also starting south but curving around the east side of the galaxy and ending up going north with the SN at its base. These likely show the paths of the colliding galaxies. Assuming 26 million light-years the galaxy is about 35,000 light years across as seen from our perspective.

Colliding galaxies as is likely the case here, create a large number of massive new stars which will quickly go supernova after using up their huge fuel supply in only a few tens of millions of years. So seeing a supernova in one is not all that unexpected. It does make the fifth Arp galaxy I've imaged with a supernova going off in it. Arp often didn't realize it but many of his galaxies were highly disturbed and thus creating massive, short-lived stars destined to go out with a very big bang. In fact, SN hunters target many of them for this reason. A good paper on this galaxy is at: http://articles.adsabs.harvard.edu/full/1990PASP..102...41K

There was a lot of confusion about the SN on the net. Many at first thought the bright star to its west was the SN. That is just a star in our own galaxy. Though I found several web pages that still point to it as the supernova even though many images taken before the supernova show this isn't correct. When discovered, it was said to be magnitude 14.6 brightening to 14.4 the following day and 13.9 a few days later. Unfortunately, it was cloudy here until a sort of opening on the 21st. It closed before I could get but 4 luminance shots. I got the needed color on the 28th but clouds moved in on the blue frames. This cost blue in the fainter areas of the galaxy as it just didn't get through the clouds. Other problems with the mount driver conflicting with something in my computer has made getting further color data impossible so I'm going with this. My quick estimate shows the star at 13.6 magnitude in my image. If you look at early images when it was fainter such as the discovery image at:
http://www.skyandtelescope.com/community/skyblog/observingblog/New-Supernova-in-Leo-136977918.html the SN appears far brighter than the two star-forming regions nearby. Yet it appears about the same brightness in my image. This is due to my stretching the image to bring out the galaxy. This reduced the contrast between the two. Measuring the actual data shows the SN to be about 5 times brighter than the star clouds. Many SN hunters use red sensitive cameras as well which would also increase the difference between the white of the SN and blue of the star clouds.

There are several galaxy clusters in the image. The one to the upper right is WHL J102522.5+170225 with 17 galaxies with no diameter given. Why the anchor galaxies distance is so different from the cluster's I don't know. The cluster below the galaxy is GMBCG J156.22001+17.21934 with 12 galaxies in an undefined area. At least its distance does match that of its anchor galaxy. A third cluster is further east and south of the galaxy, GMBCG J156.54392+17.04437 at 3.6 billion light-years. It contains only 8 galaxies but its distance is the same as that of the anchor galaxy. Southwest of the galaxy is yet another cluster; GMBCG J156.13244+16.99977 at 3.7 billion light-years. It's distance matches that of the anchor galaxy as well. It contains 10 galaxies in an unknown area. Several other clusters are noted in the image at NED but seeing nothing at those positions I didn't include them in the annotated image.

CGCG 094-040 is a rather obvious galaxy in the image but without any redshift data. I included it with a question mark for the distance. Likely it too is at the 0.61-0.62 billion light-year distance of the other CGCG galaxies in the image.

What's missing are any galaxies at the distance of Arp 263. It does seem rather alone in the universe yet apparently did merge with a companion.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp263.jpeg

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

Related Designations for ARP263

ARP264

Arp 264/NGC 3104 is a rather chaotic, irregular, dwarf galaxy in Leo Minor It is classed as IAB(s)m. Redshift would indicate a distance of about 39 million light-years. Tully-Fisher measurements put it closer at about 31 million light-years. I'm siding with the closer measurement based on how much detail I'm able to resolve in this little guy. The blue regions are also HII regions but the red has been drowned out by the intense blue of stars forming in them. This is another I should collect H alpha data on but probably never will find the time to do so. The galaxy was discovered on March 18, 1787 by William Herschel. As with most Arp galaxies, he discovered it isn't in either of the Herschel 400 observing programs.

Arp classed it under Galaxies (not classifiable as S or E): Irregular clumps. His comment was: "Faint diffuse outer material." That faint outer material doesn't appear so faint in my image when compared to his. Apparently, the spectral response of the film he used wasn't appropriate for picking out the outer regions of this galaxy.

while NED lists over 3000 galaxies in this field most are fainter than 22.5 magnitude which is my limit on this image taken under rather poor skies. I've prepared an annotated image showing distance to the very few galaxies NED had any redshift data on. Not much of interest turned up.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp264.jpeg

Sloan Digital Sky Survey image:
http://cseligman.com/text/atlas/ngc3104wide.jpg

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

Related Designations for ARP264

ARP265

Arp 265/IC 3862 is a very odd object in Canes Venatici located about 210 million light-years away. Arp put it in his class galaxies with irregular clumps. Though a note at NED incorrectly says "galaxies with adjacent loops." It is also known as IC 3862 which NED then splits into two galaxies only 2" of arc apart! One is centered on the brightest part of the galaxy and the other two seconds west where little is to be found. The error circle for the location of the western galaxy is 1.25" while that of the eastern is 0.5" so they could nearly overlap and be the same object. One note at NED also says "Possibly consists of two bodies." It certainly has the look of a possible merger in progress. Arp's only comment on it is "Resolution of stars or knots." Southeast of Arp 265 about 14.3 minutes is KUG 1252+361. This is a distorted spiral at the same distance as Arp 265. A note at NED suggests it has a double nucleus. I doubt that but it certainly is distorted. It was discovered by Max Wolf on March 21, 1903.

When I go to research a field at NED I normally find the error circle for an object to be 0.5" making identification easy. In this field, many objects are in error circles as large as 5". Even objects from the Sloan survey have unusually large error circles. The object I identify as a quasar at 11 billion light years in the annotated image has a listed location that puts the object I've identified as the quasar at the very top of the error circle. It is listed as 20.0 magnitude and that matches my reading on the object I've labeled. There is nothing but black space where the catalogs put it. Interestingly, it isn't listed by any Sloan ID, only as [HB89] 1251+362, WEE 077 and [VCV2001] J125421.9+360039. Almost due east of Arp 265 is an object I show as both a galaxy and center of a galaxy cluster (G/GC). In NED it is listed 4 times, three with a redshift, none of which agree as to position, magnitude or distance. The error circles of all include the galaxy I've assumed to be the cD galaxy of the group. Two of the three entries calling it a galaxy have redshifts listed as 2.6 and 2.7 billion light years but the cluster is listed at 2.8 billion light years. I'm used to things clicking with an accuracy of a few hundredths of a second of arc but here I vary from the catalogs by up to 6" of arc on some objects. Those few with small error circles I am getting to my usual accuracy so don't think it is my measurement that's off. Never thought I'd say that but seems correct. The galaxy cluster is MaxBCG J193.58591+36.08206 and is listed as having 19 members but no diameter is given.

There are some distant objects in this image. A quasar at 11 billion light-years and a galaxy in the upper right corner at 5.2 billion light years.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp265.jpeg

14" LX200R @ f/10, L=4x10 RGB=2x10x3, STL-11000XM, Paramount ME

Related Designations for ARP265

ARP266

Arp 266/NGC 4861/IC 3961 is a rather strange galaxy about 50 million light-years away in Canes Venatici. Arp classed it under Galaxies (not classifiable as S or E): Irregular clumps. It appears much like an irregular galaxy that consists of mostly a chain of OB star clusters in HII regions. Most are star-like except for the huge region at the south end. Most classify it, however, as an SBm. Looking through the Hubble archive I found a 160 second image of the OB groups in the galaxy. Most were severely underexposed and so noisy I didn't try to clean up the image. But the region of the huge association at the south end was so bright the exposure time was sufficient though lots of hot pixels remained and some artifacts they put in processing it. It doesn't resolve individual stars in the association but the HII emission is really is obvious. If I find time next spring I'll try adding some HII data which should make these HII regions really pop out in H alpha red. The line of bright dots extending to the upper left is the gap between CCDs in the camera, not real objects.

The galaxy was discovered on May 1, 1785 by William Herschel. It isn't in either of the Herschel 400 observing programs. On March 21, 1903 Max Wolf found it but gave a slightly different position so it was recorded as IC 3961.

This image was taken through some heavy haze over the lake that really did a number on my blue and green data, especially blue. I'm not confident of the color balance as a result but think it close, maybe a bit weak in blue if anything. Due to the haze, the two bright stars at the upper left really did a number on the image sending a fog across it. In removing it and due to the low transparency, even though this used twice the luminosity data I normally use I wasn't able to go very deep. So there's nowhere near the normal background galaxy count. It didn't help that I tried a couple new processing techniques that, while helping the galaxy further reduced the depth of the image. I should have masked out much of the image before applying these but didn't do so. But thanks to them the little galaxy at the far left above center, beyond the lower bright star shows far more detail than it would under my normal processing. It is MCG +06-29-011 at 375 million light-years. I'll know better next time how to prevent this loss to faint regions. Since the galaxies came out well I didn't go back and redo the processing.

Refer to the annotated image to locate the objects referred to below:
Below the OB association, about 3 minutes and a bit to the left, is a lone blue star with a distant red near star-like galaxy to its left. This blue star is really quasar SDSS J125903.93+344702.4 at 5.8 billion light-years. The galaxy is SDSS J125906.17+344659.3 but I have no distance data on it. Further left (east) is the bright S0 like galaxy 2MFGC 10287 at 650 million light-years. Above it, the small round blue galaxy is SDSS J125924.11+344904.1 at 725 million light-years. To its left is the bright spiral galaxy KUG 1257+350 at 425 million light-years. Further east and down just under a blue star is a small but "bright" blue galaxy. It is SDSS J130001.34+344638.0 at 475 million light-years.

The bright galaxy above Arp 266 and a bit left is LEDA 101479 at 54 million light-years. Its redshift is so close to that of Arp 266 that it is reasonable to say it is a member of its local group. At the top of the image well left of center is the very faint trail of the asteroid (132462) 2002 HT12. It's estimated magnitude was listed as 18.6. It seems quite a bit fainter than that. Normally such an asteroid would be very obvious. likely the poor transparency had something to with its faintness as well.

The most distant galaxy in the image I found is SDSS J125829.54+345804.1 at 4.6 billion light-years. To find it start with Arp 266 and go northeast to two rather bright blue stars with two orange stars between them that point at almost a right angle to the line connecting the blue stars. These orange stars point right at a very bright blue star. Beyond the blue star, a bit south of the line the two orange stars define is a fainter orange "star", is a galaxy. It is 21.4 magnitude and was thought to be a star until its spectrum showed it to be a distant galaxy.

I've included a black and white HST image of the star cloud at the southwest end of the galaxy.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp266.jpeg

14" LX200R @ f/10, L=8x10' RGB=3x10, STL=11000XM, Paramount ME

Related Designations for ARP266