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

ARP267

Arp classified Arp 267 in galaxies (not classifiable as E or S): Irregular clumps. He said of it: "Semi-stellar nucleus, faint oval ring outside." I'm not sure which of the knots he is considering the "semi-stellar" nucleus. The big blue one is an HII region where most of the current star formation is going on. It's their blue light that gives it the color. Or is it the fainter only slightly blue object under it? It is closer to the center. Or is it the condensation in the only slightly orange area to the NE? It's far off center but of the right color for a galaxy "core". Though an irregular galaxy isn't called irregular without reason. I doubt this one even has a nucleus.

The galaxy is known as UGC 5764 and is classed as IB(s)m and is located in Leo Minor. It is a very low surface brightness irregular, dwarf galaxy. Notes at NED indicate there is little current star formation but its blue color would indicate it certainly had some major star formation not all that long ago as current formation doesn't appear sufficient to keep it blue for long. The disk also appears warped. I'm puzzled by the orange core appearing to be at the NE (upper left) end of the galaxy. Nothing in the notes indicates there even is a core let alone it being off center. But this is an irregular galaxy and one odd enough to make Arp's list. At first, I thought that with such weak color data due to its faintness my color was at fault but then I looked at the SDSS image and even in their super enhanced color image the area where orange stars dominate is the same as in my image. As with most Arp galaxies, Hubble hasn't imaged it.

The galaxy's redshift indicates a distance of about 40 million light-years so this is a rather close but very small, faint galaxy. But then NED also lists a redshift independent distance estimate of only 22.5 million light-years. I'm no expert in the Tully-Fisher relationship of spiral galaxy rotation rate to its actual luminosity, the method used here. Luminosity varies as the 4th power of rotational velocity at the core. I don't know how reliable it is when applied to irregular galaxies. Notes do say its rotation curve is normal near the core so it may work here. But at 22 million light-years Cepheids should be visible, they are a primary standard candle, T-F relationship is a secondary one. So Cepheids would be a far more reliable method. Since this wasn't used it makes me wonder about this distance estimate. The lack of Cepheid data might imply a distance too great for them to be seen. Though they are usually easily seen at 40 million light-years, getting too far at 100 million light-years. Recently a new class of super long period Cepheids has been discovered. They are bright enough to extend the primary standard candle to 300 million-light years in galaxies with them. Apparently, no one has used a large scope on this one to look for Cepheids. I just am not seeing enough detail in my image to support the nearer distance nor in Arp's image.

For those who like to compare dwarfs to giants, note the only other galaxy in the image to show much detail toward the left edge and above Arp 267. It is 1,100 million light-years away, 27.5 times further away yet is about one-third the angular size of Arp 267. It's rare for me to see much detail in a galaxy at that distance.

This image contains the most distant object I've imaged, at least that I know I've imaged I should say. Of course, Arp would disagree. It is the quasar SDSS J103711.04+313433.5. It has a Z of 4.89 for a distance of 12.5 billion light-years using 5 year WMap data at NED. It is so far away it is no longer blue. Few quasars are seen at this distance, the universe was just too young for them to have fired up yet. It would be another 8 billion years before the earth was formed for instance! At the common distance for quasars, they shine with a very blue light as they are super hot glowing mostly in the ultraviolet. This is then red-shifted to blue light by the universe's expansion. But this one is so far away and moving away so fast the ultraviolet has been shifted down into the infrared! In fact, it shines at magnitude 19.5 in the infrared but at magnitude 24 in blue light. I can't be more exact as it varies greatly at this frequency. Looking at the Sloan data it varied from 24.3 to 26.1 in their green filter that also picks up blue. Yet it held very constant at 20.7 to 20.8 in the red filter and even more constant at 19.5 in near infrared. Since my camera is very insensitive to red light it is seeing the overall brightness of it at about 22.7 and thus very near my limit for this night. Trying to wrap my mind about seeing something at this distance with my system is just impossible. When I started imaging over 50 years ago even 200 million light-years seemed beyond anything I could dream of imaging using my wildest imagination. Two billion light-years was at the known limit for the 200" at the time. Imaging something this distant seems as impossible to me as landing on the moon must have seemed to my grandparents (none of whom lived to see it).

The annotated image shows galaxies and quasars over 1 billion light-years distant that I found in NED. Note that doubling z doesn't double the distance if z is large (above .5 or so). Fortunately, there are calculators on the net that make dealing with this far easier than doing the math yourself, unless you're a masochist that is.

Two very bright (for my images) asteroids show up in the image. Glaring at us directly west of Arp 267 is the 157th asteroid, Dejanira shining at about magnitude 13.4. Almost directly above Arp 267 at the very top is asteroid # 70643 known as 1999 TE242 at an estimated magnitude of 18.7. Seems brighter than that to me.

Arp's image, inverted from mine:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp267.jpeg

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

Related Designations for ARP267

ARP268

Arp 268/Holmberg II is part of the M81 group and is located about 3 megaparsecs from us, about 10 million light years. It is classed as a Magellan type irregular galaxy. Arp classed it under "Galaxies (not classifiable as S or E); Irregular clumps. Being close and having blue giants up to 19th magnitude I was able to resolve many of its brighter stars and star clusters. Arp's comment: "Resolution of stars: Note linear loop of emission regions." I'm not sure how a loop could be called linear but I'm sure he is referring to that looping feature on the east side (left) of the galaxy. The CGPG catalog notes: "Large post-eruptive blue irregular with compact core and many knots." I'm not such what is considered the core of this guy. I can't say I see it in any image I looked at.

There are several interesting galaxies in the field. Above and slightly left is the oddly red spiral NPM1G +70.0037. I find no distance estimate. Galaxy Zoo in studying the Sloan Deep Sky Survey images has discovered a new class of spiral galaxies, red spirals. This appears to be one of those. Spiral arms are usually very blue as this is where new star formation is going on. Without current star formation, it was thought the spiral structure would quickly break down. So this class of spirals is a real problem to explain.

Down and to the left of the red spiral is the double spiral KUG 0815+709. Apparently, that bright spot on the upper arm is a second galaxy. Both it and the red spiral are strong IR emitting galaxies.

Most galaxies in the image are anonymous, including the interesting looking spiral below the double spiral KUG 0815+709 and the narrow edge on spiral seen through Arp 236's east side just above that loop of star forming regions. I'd love to know more about it but couldn't find even a mention of it anyplace.

There is a large galaxy cluster centered just above my image, RX J0819.3+7054. Some of its members are seen along the top center of my image. They are somewhat reddened by their great distance of about 2.7 billion light years. None were listed individually, however. Therefore I can't separate which are cluster members and which are just background galaxies. Two other clusters are listed in this region to add to the confusion of who belongs to what.

An excellent image of this galaxy taken by the 10 meter Keck telescope is at:
http://cse.ssl.berkeley.edu/bmendez/pics/TRGB/Holmberg_II.jpg

Arp's image of this galaxy is one of his best, indicating a very good night atop Palomar mountain.
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp268.jpeg
Arp's image was taken in blue light it appears to show the super hot blue stars recently formed in the galaxy.

14" LX 200R @ f/10, L=4x10' RB=2x10'x3 G=1x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP268

ARP269

Arp 269 is made up of NGC 4485 and NGC 4490. The big one is NGC 4490 which is sometimes known as the Cocoon Galaxy. They are located in Canes Venatici which is high overhead in the evening this time of year. These two have had a near collision that has ripped stars out of both and started massive star formation in them as shown by the many bright HII regions (pink). NGC 4490 gets the Cocoon name for being embedded in a faint cocoon of stars much as a pupa is in a cocoon. I've posted two versions of this guy. The first as it is more normally seen and then a very deep processing to better show the cocoon of stars that surrounds it. The distance to these two is rather vague. I see published papers giving distances ranging from 25 to 60 million light years. Those citing about 35 million seems better researched so that's what I'll go with. There's very little on the net about these guys other than published papers so I don't have any links that are of much use here. I would have thought it a target for Hubble but it isn't in their database that I can find. But Chandra has looked at it in X-ray light.
http://chandra.harvard.edu/graphics/press/03_releases/052703_images/ngc4485.jpg while an HST image of NGC 4485 can be seen at: http://cseligman.com/text/atlas/ngc4485hst.jpg

Arp put it in his classification for Group Character: Connected Arms. I don't see how this pair varies from many other interacting pairs he put under other categories in his atlas. NGC 4485 to the north is classified as IB(s)m pec while NGC 4490 is classified at NED as SB(s)d pec. The pair was discovered by William Herschel on January 14, 1788. Both are in the original Herschel 400 observing program as two individual listings. My notes from April 28, 1984 with a 12.5" f/6 telescope at up to 150x on an excellent night in the New Mexican desert read: "Small and dim with no detail. In the same field with much larger and brighter NGC 4490. A Mutt and Jeff pair. Appears slightly elongated. Hard to judge this one as my eye keeps jumping to NGC 4490." The entry for NGC 4490 reads: "Bright with stellar nucleus. Some detail seen in arms. Appears to be a highly tilted spiral. A bit more tilted than M31. A fine object especially when paired with NGC 4485. Seems about 9.5 magnitude, brighter than Burnham says." It's obvious I'd not seen anything on this pair before looking at it as I thought I was looking at a classic spiral rather than a messed up one with no defined arms.

Our galaxy is very overdue for a naked eye supernova event. Not one has blown in our galaxy, that we could see that is, since the invention of the telescope much to astronomer's dismay. We find them all the time in very distant galaxies where they are faint and difficult to study. So when one blows in a nearby galaxy it causes lots of observatories to drop what they were doing and get their instruments trained on the exploding star. One did so in NGC 4490 shining "brightly". It blew in 2008 and is known as 2008ax being discovered on March 3 by Link Observatories automated supernova search telescope and by Japanese amateur Koichi Itagaki who has discovered over 100 supernovae. This one was bright enough to be seen in amateur telescopes of 8" or larger size when viewed from a very dark location. It is shining at magnitude 13.2 as best as I can measure it against the background of the galaxy in my image.

The distance to NGC 4490 is a bit uncertain. I've seen estimates from 35 to 50 million light years. Maybe they'll have to pin it down a bit closer to get meaningful results from the study of this supernova. This is a very blue galaxy in which star birth has been going on at an extremely high rate due to interaction with a companion galaxy NGC 4485 also in the image. Many of these new stars are super-massive blue giants that are very short lived. Lasting only a few million years before they blow up. So it isn't at all surprising to find a supernova in this galaxy. My supernova image was taken in strong moonlight and had very limited color data due to clouds and lousy seeing. But it does show the supernova when it was about 13.5 magnitude. It apparently brightened a bit after my image was taken. Of course, all this really happened at least 35 million years ago so this is old news to residents of the galaxy, assuming they could survive living in such an active galaxy with the intense radiation caused by its star birth condition. Be very glad we don't live in such a galaxy. The pink regions easily seen in my image are due to HII emission from areas where star birth is still going on. My lousy seeing and limited color data make them hard to see in the supernova image.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp269.jpeg

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

Related Designations for ARP269

ARP270

Arp 270 is a pair of NGC galaxies, NGC 3395 and NGC 3396. Both were discovered by William Herschel on the night of December 7, 1985. NGC 3395 was also discovered at a slightly different position by Stephane Javelle on May 13, 1896 which got it the IC 2613 designation. Only NGC 3395 made the original Herschel 400 observing program even though fainter than NGC 3396 with isn't in either. My notes from April 15, 1985 under humid conditions at up to 150x with my 10" F/5 reads: "Small, circular, puff of a galaxy just west of NGC 3396."

Several papers refer to NGC 3396 as being possibly disrupted by its companion. It is classed as a barred irregular galaxy. Though one paper claims it is SBm pec as they see hints of two arms. I found very few images of this pair on the net and those I did find didn't show the large spray of stars torn from NGC 3396, with the exception of the Sloan image which shows it to some extent. Arp's doesn't show it either. There is a dark region in this spray along the west side of NGC 3395. That is not a processing artifact. It was there to that extent in the original FITS data. It is hinted at in the Sloan image as well. I don't know what interaction could create this "shadow" but it is definitely real.

NGC 3995 is classed as midway between a normal spiral and a barred spiral having characteristics of both. I'm afraid I'm not seeing the barred characteristics in my image. They may be seen at other wavelengths such as radio. Arp's comment on it refers to the blue knots when he says: "Note arc form of emission knots."

Yet another paper classes both as Sc galaxies. It's nice to know galaxy classification is so easy to determine.

The spiral near the top of page left of center is SDSS J105030.39+330846.4, an IR galaxy indicating a lot of star birth is happening in it, is about 800 million light-years away and appear somewhat disturbed. This is easier to see if you double the size of the image.

The Zwicky galaxy cluster ZwCl 1046.0+3320 is near the right edge a bit above Arp 270. I see few galaxies right where its center is but a bit closer to Arp 270 there's quite a nice group clustered around a very red galaxy about 4 billion light-years away, SDSS J104852.82+330329.7. Many other apparent groupings exist in across the image but none were mentioned in NED.

Arp 270 is a member of a small group of galaxies all at about 90 light-years. Two of the others are at the very bottom of my image. They are IC 2604 and IC 2608. The oddly distorted spiral galaxy is IC 2604. It is classed as SBm pec. While the peculiar status is obvious with the two odd arms and a third that is mostly two star clouds, I don't see the bar that the "B" indicates. Sometime in the past, it appears to have had a near miss with one of the others in the group or ate one. Something sure tore it up. NED classes IC 2608 as a spiral. Looks like an SO to me.

You may note the dimensions of this image are unusual for me. That's because the first night I was imaging this group I was clouded out after only a few frames including 1 of each color. A few nights later I returned to it forgetting all about the two IC galaxies. So I centered Arp 270 and got some very good data just before dawn. That was last January. It wasn't until I went to process the image I realized I'd missed the two IC galaxies. So I salvaged the cloudy data as well as I could and tacked it onto the bottom of the main image. I had to crop the sides a bit as camera orientation had changed between the two images. I rarely remove the camera but did so between these two sessions, unfortunately. The bottom of the image is rather poor compared to the rest due to lack of data because of the clouds. They also created a horrid halo around the star at the very bottom. I was a bit heavy handed removing that glaring halo. When I realized what I'd done it was too late to go back and correct it.

In researching this one I came across a very good simulation of a galaxy merger of the type that is going on here. Back in the early 80's I used a 25Mhz computer with all of 4 megabytes of memory (cost $1000 a megabyte back then) to run galaxy collisions. It only could deal with about 10,000 points and took hours to calculate one simulation but showed it from three viewpoints which was nice. The only factors it considered was gravity and the motion vector of each point, which was considered to all be of the same mass. The simulation I found considers millions of points and takes into account many factors including dust and gas as well as the temperature of the dust and gas as well as how they affect the merger process. Obviously, they didn't use my ancient computer. The simulation is at: http://www.youtube.com/watch?v=agqLEbOFT2A

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp270.jpeg
Chandra image (X-ray) so shows mostly the hot gas heated by the collision:
http://chandra.harvard.edu/photo/2002/arp270/
Not imaged by Hubble that I could find. :(

My image data:
Main image 14" LX200R @ f/10, L=6x10' RB= 4x10' G 3x10',STL-11000XM, Paramount ME
Exposure for bottom part: L=3x10' RGB=1x10' through clouds

Related Designations for ARP270