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

ARP271

ARP 271, in Virgo, is a rather classic Arp pair, much photographed compared to most Arp galaxies. Thus my desire for a better night than I had. It is two spiral galaxies, NGC 5426 (bottom) and NGC 5427 that are just now starting to interact as they orbit by each other, apparently for the first time. Some distortion can be seen in each galaxy. The arms of NGC 5426 seem to be reaching out to connect with NGC 5427. It, in turn, has some tidal effects showing. But we are seeing them in 2D rather than 3D which makes determining the real relationship between these in space difficult to determine. For some insight as to what is happening here, I will refer you to the article and great image taken by the Gemini South telescope with nearly 6 times the resolution I can achieve here. I wish now I'd have taken some H alpha data with this as both galaxies are rich in HII regions as shown by the Gemini South image. http://www.gemini.edu/twinspiral The pair was discovered by William Herschel on March 5, 1785. NGC 5426 made the Herschel II 400 observing program. My notes from that failed to arrive when we moved to Minnesota so I can't give them.

Arp classed the pair under "Group character: connected arms". His comment reads: "Arm's linked. Note bifurcation in arm of N spiral." NGC 5426 is classed by NED as SAc pec. while NGC 5427 is classed as SAc pec. Sy2. The latter meaning it is a Seyfert 2 galaxy with an active nucleus. I find no consensus on their distance. Redshift puts them a bit over 130 million light-years away but various papers I've seen put them closer, more like 90 to 110 million light-years. The ability of Gemini south to resolve so many HII regions would argue for these somewhat closer distances.

While there are a lot of faint fuzzies in the image, most are cataloged under the LCRS catalog, that stands for Las Campanas Redshift Survey. Oddly, the nice big bright entries have no redshift value in NED. For instance, the large orange elliptical NW of Arp 271 is very obvious. It is cataloged as LCRS B140024.4-054536 without a redshift. Most that do carry a redshift are the tiny yellowish orange galaxies. Those fall into two camps, those near Arp 271 are about 1.1 billion light-years distant and those in the SW corner belong to a different group being 1.7 billion light-years distant. But the larger, likely closer galaxies have no redshift data that I could find.

In my north up image the lower galaxy seems to my brain to be nearly face on but in the Gemini image, it appears quite tilted. So I rotated my image for east up and suddenly it looked very 3D and tilted. I've attached the cropped rotated version, see link for full north up version. Is it just me or does it seem to appear to change orientation for you as well?

Arp's image of the pair with the 200" Palomar scope is at:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp271.jpeg

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

Related Designations for ARP271

ARP272

Arp 272 is a trio of galaxies in the Hercules cluster. Arp put it in his category for group character, connected arms. The disks of all three do overlap as seen from earth. Whether they really overlap is questionable. It could be just an alignment due to our viewpoint. Their redshifts are rather different which would argue this is just an illusion though the lower two both have plumes that are likely due to interaction. So they may be related but just passing by each other at rather high speed. The interaction, if any could be happening as we look or happened some time ago with them lining up from our viewpoint. It is hard to tell.

The eastern galaxy is NGC 6050 classified by NED as SB(rs)cd, the western is IC 1179 classified by NED as SB0^0^. They are about a half billion light-years distant. NED doesn't consider IC 1179 part of Arp 272 yet most sources consider it one of the two or three galaxies that make up Arp 272. Again Arp's catalog (1966ApJS___14____1A.pdf) lists Arp 272 as NGC 6054 which can't be correct. In any case, the southern pair was discovered twice by Lewis Swift. Once on June 27, 1886 becoming NGC 6050 and again on June 3, 1888 becoming IC 1179. It is likely he saw these as one galaxy as even in larger scopes than his they can't be seen as two objects. The eastern galaxy seems to only carry the NGC 6050 name at NED but most consider it also as IC 1179. It is classified as SA(s)c.

This brings us to the northern object, UGC 10186. Some sources consider it a piece of the pair that has broken off. I have trouble with that and see it as yet another galaxy. If so this may be a triple system. NED considers it part of Arp 272 and calls it a double system which I find rather confusing as it ignores IC 1179. Seligman however considers IC 1179 the same as NGC 6050. He says the two are PGC 57053 and PGC 57058 right to left. Anyone confused?

This data was taken September 13, 2007. I didn't have the tools to do it justice back then. I need to reshoot this one. It also contains ARP 71, Arp 122 and Arp 172. Details are in the annotated image. The annotated image shows details on many other galaxies in the cluster and beyond it.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp272.jpeg

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

Related Designations for ARP272

ARP273

Arp 273 is a near collision in progress. The large galaxy is UGC 1810, the other spiral, UGC 1813. They are located about 330 million light-years away at the southeast corner of Andromeda. It's obvious that UGC 1810 is highly distorted. One arm looks more like Saturn's F ring than a spiral arm and seems to make a complete ring about the galaxy. It's hard to tell if NGC 1813 is distorted. It looks greatly distorted to me as the arms are almost straight but that is seen in other barred spirals. But it has faint a faint arm that curls back and runs along the arm while the ends of the bar, if it is a bar, seem to end differently. The left one ends in a faint blob while the right one seems to curve back from the arm of UGC 1810 as if repelled by it. Obviously, it isn't but sure gives that appearance. In any case, they curve very differently, likely due to the near collision. To appear so large at such a great distance these have to be two very large spiral galaxies. Indeed they are. I measure UGC 1810 as being 210,000 light-years in diameter. It is probably larger unless seen exactly face on. I measure NGC 1813 at 160,000 light-years including the long eastern plume.

When galaxies pass by like this they trigger massive star formation. We see it in the arms of the bigger galaxy UGC 1810, this is common, but it is confined to the very core of UGC 1813. This is not unusual. Also, UGC 1810 is a LINER galaxy. It doesn't seem to have an active core, so we know the near miss hasn't yet caused a feast for the black hole by sending matter its way. Yet UGC 1813 seems to have a heck of a lot of disturbance at its core to trigger so much star formation. This all goes to show it is very hard to predict just what will happen in a near miss like these two have encountered. Nor do we know what long-term changes it will trigger. I can't even find if the two are gravitationally bound. If so they will merge in the future.

This is one of the rare images I can display at my full resolution of 0.5" per pixel. Something my seeing rarely allows, unfortunately.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp273.jpeg

14" LX200R @ f/10, L=6x10'x1 RGB=2x10'X2, STL-11000XM, Paramount ME

Related Designations for ARP273

ARP274

Arp 274/NGC 5679 consists of three galaxies in the constellation of Virgo. Arp put them in his category of "double galaxies with connected arms." His note reads: "Perturbation of arm by small galaxy to east." He is drawing several conclusions here that may not be correct. The first is the connected arms classification. NED has this to say about the two main spirals: "Delta V > 1000 km/sec; probably an optical pair." That is they consider the two galaxies redshifts to be too different for them to be anything more than an optical pair. I'm not sure that alone is sufficient but I also see no evidence of interaction between these two. Putting the two together I have to agree they are most likely an optical pair. Note too, in the annotated image there are several galaxies with redshifts that match the center galaxy and several that match the western member. It appears we really do have two different galaxy families in the image, the largest of each family nearly along the same line of sight as seen from earth.

That brings up Arp's note. It is true the eastern end of the middle galaxy's eastward arm has a sudden kink. This apparently was sufficient for Arp's conclusion that this is due to perturbation by the small galaxy off the arm. But this is the only evidence for this conclusion. In all other M51 type interactions in his Atlas, the entire arm is distorted not just the end. It's hard to explain just a sudden change like this as caused by an outside gravitational field. The effect should gradually begin. Maybe as seen in the third dimension it does. But how you tell this from a 2D image I don't know without further redshift data on that arm. The other problem is that there is no distance determination available for the small third galaxy. It too could be unrelated. It may be related, but, to me, it is far from being a solid conclusion. The odd fringes of stars off the small one may help this argument some. However, I'd expect them to show some orientation toward the main galaxy rather than at right angles if this were the case. Again, a 3D view might show this is the case. I need far more evidence before accepting this, however. NGC 5679 was discovered by William Herschel on February 12, 1793, but isn't in either of the Herschel 400 observing programs.

The low surface brightness galaxy to the southeast of Arp 274 is UGC 09385. The UGC catalog lists it as a dwarf galaxy! It certainly has a low number of stars but with a diameter of about 50 million light-years, it is not very dwarf-like in size.

Of the galaxies to the southeast of Arp 274 at 330 million light years, the eastern one seems to have a comet sticking out of its southern end. NED lists it as a separate galaxy, SDSS J143557.41+051822.4. No redshift is given. Maybe it has a second arm hidden behind the foreground galaxy giving this illusion.

There are several galaxies at 800 million light-years scattered across the image indicating yet another family. This field also contains more quasars than average. One, in the lower right corner, is listed both as a galaxy and quasar at 1.9 billion light-years. Its spiral arms are clearly visible in my image. I'd think a quasar would be so bright as to drown out the galaxy at my resolution. It must be a very weak quasar.

Along the top of the image toward the left is the asteroid (237813) 2002 CP84 at an estimated magnitude of 18.4. That appears reasonable in this case.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp274.jpeg

14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Related Designations for ARP274

ARP275

Arp 275/NGC 2881 is a pair of colliding galaxies in Hydra nearly a quarter billion light-years from earth. Arp had no category for colliding galaxies. Though he did have one for interacting galaxies. Many dozen of his galaxies were interacting but only 6 made this category, This was the first of the 6. Unlike most entries, he had no comment for this entry.

The two galaxies making up Arp 275 are also known as VV 293a and VV 293b with VV 293a being the one on the left (east). It is the only one of the pair to have redshift measurements. It isn't classified at NED other than mention it has HII regions. VV 293b to the west is classified at NED as Sbc? pec. A note at NED from the MCG catalog says; "Bright, interacting. Two galaxies Fd in close contact with very large deformations." A note with the VV catalog says; "On the (red) POSS print the two major bodies are not in contact against the background of a homogeneous disk." I can't tell from any image if they are in contact. To me, it appears that the eastern galaxy may be slightly in front of the western one. Since I can't really tell where one galaxy ends and the next begins I measure the long axis of the projected pair at about 74,000 light-years. So these aren't very big galaxies, even including the plumes created by their interaction. The pair was discovered by Lewis Swift on February 9, 1886 using a 16" refractor.

The only other galaxy in the image with any information is IC 2482 in the southeast corner of my image. It is listed as an E+ at NED and much closer than Arp 275 at about 175 million light-years. A note at NED says of it; "The gradient of brightness in halo is smaller than in a normal E." Oddly it is quite a bit brighter and larger in angular size than Arp 275 yet wasn't discovered until March 14, 1899 by Herbert Alonzo Howe using a 20" f/15 Alvan Clark-George Saegmuller refractor at Chamberlin Observatory in Denver. How Swift missed it I don't know. While it is partly off my frame I measured its the length of the side fully on the frame and doubled that to get a size of 156,000 light-years. Twice the size of Arp 275. My sister-in-law lives in a southern suburb of Denver and every time I've been there the seeing has been awful. Seems like a poor place for an observatory from my limited sample. The observatory is right in Denver only about 3 blocks east of the University of Denver campus of which it is a part, right beside tennis courts and ball diamond (both unlit last I knew). Conditions must have been much better in 1899! It still is open two nights a week to show the public the moon and planets, about all you can see from that location today. Howe managed to find 60 IC objects from there. Not much light pollution in his day.

Nothing else in the frame has any distance information useful for an annotated image so I didn't prepare one.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp275.jpeg

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

Related Designations for ARP275

ARP276

Sometimes an image turns out very differently than you expect. This certainly is one of those. I never suspected the galaxy was buried in galactic cirrus. I saw a hint of it in the raw files as they came in. Only the brightest part showed however and looked like a reflection. So when I stacked and calibrated the images it came as a shock to find the field full of the Integrated Flux Nebula.

Arp 276 consists of two galaxies which are barely showing signs of interaction. Since we can't see them in 3D its possible one is well in front of the other such that gravitational interaction is minimal. Some distortion of the southern galaxy's NE end is evident but that's about it. Radio data shows these to be rather normal galaxies giving little hint of a collision in progress from what I found. Arp notes; "Both intersecting edges seem dimmed." Hard to say if that's due to anything more than one obscuring the other. I'd like to see spectral data for the overlap region.

The northern galaxy is NGC 0935 classed as Scd. The southern is IC 1801, an SBb galaxy. Redshift shows it slightly in front of NGC 0935 but this is not a reliable indicator. The pair is about 175-180 million light-years away by redshift data. Each galaxy has hosted a supernova. SN 2006F was seen in NGC 0935 and SN 1976 was seen 30 years earlier in IC 1801. NGC 935 was discovered by Lewis Swift on September 18, 1885 but he apparently didn't see IC 1801. That had to wait 12 years until found by Stephane Javelle on December 27, 1897.

This region hasn't been surveyed by the SDSS. The group is in central Aries. I need to redo it with a lot more exposure time to pick up the integrated flux a lot better than I did with my normal rather limited exposure time. NED shows only a dozen other galaxies in my image, none of which has any redshift data.

The Integrated Flux Nebula or Galactic Cirrus as it is also called is fine dust above and below the plane of our galaxy that is lit by the combined light of the stars in our galaxy's spiral arms. Some of it is reflection nebula, this part is white to blue-white in color. Some though are made up of particles that glow a red color in the ultraviolet light of our galaxy's most massive stars. This is called Extended Red Emission or ERE and accounts for the reddish areas of the nebula. Normally we think of reflection nebula being lit by the light of one or a few super bright stars that are nearby. But this nebula is lit by the combined light all the stars in our galaxy though mostly this is from the supermassive stars that define the spiral arms as they account for most of the light emitted by the disk of our galaxy. While brighter pieces of it were cataloged in the LBN catalog in the 60's based on the Palomar Sky Survey plates it wasn't until 1975 that some idea of its real extent was realized by Alan Sandage who used the 48" Schmidt to image it in a 4 hour exposure. Even then it was rather dim as film just didn't have the sensitivity to see this faint nebula, even in such a large scope. Today's electronic detectors, akin to those in digital cameras but designed for long exposure work and used at rather low temperatures (I usually run at -35C) to reduce noise by a factor of 1000 or more replaced film. The first map of it was made by the IRAS satellite as much of the ERE emission was in its infrared passbands. It was its images that gave it the "Galactic Cirrus" name as it looks much the same as earthly cirrus clouds. Since then more extensive maps have been made by Earth-based astronomers in near infrared as well as visible light wavelengths. See http://www.galaxyimages.com/UNP1.html for one such effort. Still, I'd not seen anything indicating it was "big and bright" in this part of Aries though I'd seen some fainter portions in the vicinity of M15.

Some with a wider field and faster telescopes than mine might want to take some really deep images of this area and find the extent of this portion of the IFN. My system is too narrow field for such a task.

Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp276.jpeg

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

Related Designations for ARP276