This is the first part in a series based on visual observations of Halton C. Arp's "Atlas of Peculiar Galaxies". The other parts are:
I had long been interested, from an aesthetic viewpoint if nothing else, in the various oddball galaxies depicted in those few images from Arp's "Atlas of Peculiar Galaxies" that had widespread distribution. When CalTech made the entire atlas available online, I started thinking of the fascinating observing project it would make. With a little research on my part, I soon realized that I would be able to visually observe at least 120 objects with my then 12.5" f4.5 dob. I started the list on a target of opportunity basis in early 2000, eventually getting downright serious about it by fall of that year. Some of the objects, those that are also in the Messier Catalog, I have been observing for decades in apertures ranging from 80mm refractors to 25" dobs. Most of the object descriptions come from observations from my 16" f4.5 dob. Before getting to my notes on the individual objects, however, I think that a little background information would be useful. If you prefer, you may skip directly to the observations.
This was the base premise of standard "Big Bang" cosmology in the 1960s. It was supported by three pieces of evidence:
1. The relative abundances of light elements.
2. The Cosmic Microwave Background Radiation.
3. The redshifted light coming from just about every external galaxy that can be observed.
All mainstream cosmology is based on these three facts and one theory - General Relativity.
Unfortunately, not many pieces of observational evidence seem to agree with this simplified view. As a result of this there have been many additional theories tacked onto the basic theory, all trying to make the Big Bang model viable. After a while, it all starts looking suspiciously like the epicycles that were tacked onto earth-centered cosmology in an attempt to explain the motions of planets.
For example, in the last twenty-five or thirty years we have seen Dark Matter (that still has not been found), Inflation (which doesn't really predict anything testable), Cosmic Strings (for which no evidence has been observed), and most recently a mysterious repulsive force that is being called a Cosmological Constant. This relies for proof on one observation of a type 1a supernova at a Z of around 1.3 that seems to be 20% dimmer than its redshift distance would imply. Could not the observation be as easily explained by using a Hubble constant slightly lower than was used to show this "proof"? It also seems that mainstream astronomers are very busy seeking evidence to support these accepted theories, rather than developing new theories to explain the observations.
Of course, the Hubble Constant is part of the problem. In addition to having no agreed upon value, it seems to give a different result depending on just where you point the spectrometer. Part of this is due to the observations in our own near (300 MLY) neighborhood which showed that besides the portion of redshift that was supposedly due to universal expansion, there was also a large component of redshift that was due to peculiar local velocities involving large scale motion towards very massive objects. Hubble's Law assumes that if we just look far enough back in time, or out in distance, we will be able to neglect these peculiar velocities. Without some independent way to gauge distance, how reliable will distance "guesstimates" be? Comparing the results from the various high-Z supernova searches suggests that there may be a peculiar velocity component at work no matter what reference frame is chosen.
With all the problems involved in using redshift as a velocity and thus a distance indicator, what good is it?
Well, maybe redshift is not an indication of universal expansion. Maybe it has very little to do with distance. Edwin Hubble, throughout his illustrious career, always held out the possibility that redshift may have some other mechanism behind it than velocity.
One of the most vocal opponents of using redshift to determine distance is Dr. Halton C. Arp. Throughout his career, Dr. Arp has been one of the few voices opposing this practice, especially when it comes to the curious objects known as quasars. In the conventional view quasars lie at vast cosmological distances, emit copious amounts of energy, and are the brightest objects in the universe. In Dr. Arp's universe a quasar is a very young object ejected by a low redshift parent galaxy. In it's lifetime, the quasar will evolve into a BL Lac object, then into a dwarf high redshift galaxy, and eventually into a normal low redshift (but higher than its parent) galaxy.
The parent or dominant galaxy in a cluster will be an energetic type 1 Seyfert of morphological type Sa, Sb, giant E or cD. All other galaxies in that group will have higher redshifts than the parent they descended from. These energetic parent galaxies are frequently sources of radio emission, often bipolar in form, and often are associated with jets. More often than chance would seem to allow, in Dr. Arp's view, they will also have a pair of high redshift quasars, BL Lacs, or high redshift galaxies aligned with their ejection cones on both sides of the active nucleus. Rather than a black hole dragging surrounding matter into oblivion, Dr. Arp feels that these active nuclei are white holes creating new matter. There needs to be further study to either prove or disprove Dr. Arp's theories, but it remains to be seen if anyone will be granted observing time on any major facility to do research relating to these theories, since they have been branded as crackpot by the people who run the various Time Allocation Committees.
Dr. Arp set up several classes for the oddball galaxies that he had been observing early in his career, from 1962 through 1967. These were set forth in his "Atlas of Peculiar Galaxies" that was released in 1967. Dr. Arp stated at that time, "Because so many of the physical processes pictured are not understood, no rigorous attempt at classification has been made. The galaxies have been grouped empirically, putting together all the objects that look alike." There are five broad classes of objects depicted in the atlas, with anywhere from four to fourteen subclassifications in each main class. Included therein are enough interesting galaxies to keep us, as observers and imagers, busy for many nights under the stars. I will give the Arp classification of each object in the observations to follow. You can get the complete listing of objects, and all the original images, at the NASA Extragalactic Database website.
Arp 1 NGC 2857 - m12.3 sb 14.3 2.2'x2' Sc 9h24.7m +49°21.1'. Arp Classification - Spiral Galaxy with low surface brightness. In the 12.5" at 89x (16 Nagler) it was a very faint glow that was almost obscured by field stars adjacent to the galaxy. These four field stars only range in magnitude from m12.3 to m14, so the low surface brightness of the galaxy was readily apparent. At 119x (12 Nagler), the glow of the galaxy was more apparent, with a brighter small nucleus, about 10" in diameter, surrounded by a soft glow extending out to 2' diameter. At 158x (9 Nagler) with averted vision, faint hints of spiral structure were visible in the inner half of the structure. At 178x (8 Radian), this structure was slightly more apparent, but still needed averted vision to see well. Also in the field 7' to the SW at PA 210° are NGCs 2856 and 2854, AKA Arp 285.
Arp 18 NGC 4088 - m10.6 sb 12.7 5.6'x2.1' SBbc 12h5.7m +50°32'. Arp Classification - Spiral Galaxy with detached segments. In the 16" at 131x (16 N w/ Parracor), it had a bright core .3'x.1' with a central bar elongated NE - SW about PA 210°. At 175x (12 N) the N arm showed some mottling for about 1' in length, and then faded rapidly in the next .5'. The S arm was brighter than the north, fading abruptly after 2', then having a bright mass attached at the end that extended another 1' to the NW.
Arp 24 NGC 3445 & PGC 32784 - m12.6 sb 13.6 1.6'x1.4' Sc 10h54.7m +56°59'. Arp Classification - One armed Spiral Galaxy. In the 16" at 233x (9 N), it was faint, round and mottled with slight brightening in the nucleus off center in the northern half of the structure. The very faint arm wrapped around the south side of the nuclear region had a couple of faint brighter spots that would pop in and out as seeing permitted. PGC 32784, AKA MCG +10-16-24, is a very faint .3'x.1' bar about 1' to the E from the south edge of 3445. The m10 field star about 2' away to the NE definitely makes this one hard to see.
Arp 104 NGCs 5218 & 16 - 5218 m12.3 sb 14.1 1.8'x1.3' SBb/p - 5216 m12.6 sb 13.9 1'x1' E0/p 13h32.2m +62°46'. Arp Classification - E galaxies connected to spiral. With the 16" at 175x, these two are aligned NS about 4' apart, with 5218 to the north. 5218 has a faint bar about .5'x.2' aligned EW with a very faint haze extending from NE-SW about 1'x.5'. The bar has a slightly brighter almost stellar core. 5216 is a 1' diameter round galaxy that brightens to a non-stellar nucleus. At 233x with averted vision, there are some hints of additional structure E and W of 5218, where the very deep photograph in the Arp Atlas shows arcs from jets. There was no sign of the bridge between the galaxies that is shown on the Atlas image.
Arp 105 - NGCs 3561 & 3561A - 3561 m14.7 sb 14 .7'x.7' SBO - 3561A m14.3 .9'x.9' Sa 11h11.3m +28°41'. Arp Classification - E and E-like galaxies connected to spirals. This is a very nice area to get lost in for a few hours. These two galaxies are on the eastern side of Abell 1185, a cluster of 52 galaxies. In the 16" at 300x I had 24 galaxies in the field with others on the bare edge of visibility. 3561 is a small round object about .6' in diameter with a brighter core. 3561A is 1' to the N of 3561, small and oval, aligned NS about .6'x.3' in size. It has a bright almost stellar nucleus. There are very faint wings of nebulosity extending out about .3' on either side of the oval region. On the Arp photograph there is a thin stream of material extending N for about 3' ending in a small condensed object called Ambartsumian's Knot. This was not visible in either the 16" or 20" scopes with which I observed this object. Extending to the W from these two for about 12' is a dense stream of small dim galaxies with a couple of brighter NGC galaxies as outliers on the N and S of this stream. You can actually follow a pretty dense trail of galaxies for about 1.2° to the W of 3561 & 3561A. Immediately to the E of the Arp pair is another stream of faint galaxies, this time extending NS for about 20'. A very interesting field. Dr. Arp thought enough of this object and its immediate environs that he used it for the back cover of his most recent book, "Seeing Red" (Aperion, 1998.)
|Arp 155 NGC 3656 - m12.5 sb 14.3 1.5'x1.5' E/p 11h23.7m +53°50.2'. Arp Classification - Disturbed galaxy with interior absorption. With 16" at 233x it was a faint 1' diameter nebulosity. M12.5 field star immediately adjacent to west. Some hints of nebulosity to S of 3656, MCG+9-19-64 is shown in MegaStar at this position, but I was not able to definitely confirm it. 3656, at moments of good seeing, would show a hint of a dust lane dividing the galaxy from north to south.|
Arp 224 NGC 3921 Mark 430 - m12.4 sb 12.8 2.1'x1.3' Sa/p 11h51.2m +55°4.2'. Arp Classification - Galaxy with amorphous spiral arms. With 16" at 131x, small, faint, bright core. At 175x, bright core about 20" in diameter. With averted vision, a faint haze, almost oval extending to the south about 1'x.3'. There were several other galaxies in this field, MCG +9-19-213 m14.2 is 5' to the west about PA 210°. NGC 3916 m14.7 is about the same distance to the NW, PA 330°. 3916 appears edge-on, about 1.2'x.3' in size.
Arp 239 NGCs 5278 & 9 Mark 271 - 5278 m13.6 sb 13 .8'x.6' SB/p - 5279 m15 sb 13.6 .4'x.6' SBa/p 13h41.8m +55°39.9'. Arp Classification - galaxy with the appearance of fission. At 133x, it was a small spot of haze with a bright core, and another small bright spot less than 1' to the east. At 233x 5278 showed a bright almost stellar nucleus surrounded by a bright arm that faded to the north. 5279 was non-stellar, but showed no other signs of structure. At 262x (8 Radian), with averted vision, there was a very very faint dusting of nebulosity joining these two objects on their northern side.
|Arp 280 NGCs 3769 & A - 3769 m11.8 sb 13.8 3.3'x.9' SB(r)b - 3769A m14.2 sb 14 .9'x.3' SBm/p 11h37.8m +47°53.2'. Arp Classification - Interacting double galaxies. With 16" at 175x, 3769 is oval, aligned NW - SE PA 150°. It has a bright core region approximately .3'x.1' in size surrounded by an oval region 1.3'x.4' fading off to the background. At 233x with averted vision, the surrounding haze grows to about 2.5'x1' in size. Also with averted, 3769A appears off the southern end of the brighter portion of 69's disk, about .6'x.2' at PA 110°.|
Arp 285 NGCs 2854 & 6 - 2854 m13 sb 14 1.6'x1' SB(s)b - 2856 m13.1 sb 13.4 1.1x.5' Sbc 9h24.1m +49°12'. Arp Classification - Double galaxy with infall and attraction. These were mentioned in the section with Arp 1 NGC 2857. In the 12.5" at 119x, 2854 was the brightest of the three. At 178x (8R), it was elongated NE-SW PA 45°, about 1.2'x.5' with a bright non-stellar core in a nice bar about .7' in length. the arms were fainter, but easy to see, giving this galaxy an "S" shape. 2856 was a smaller oval 3.5' to the NE at PA 45°, but aligned at right angles to 54. It has a 1'x.5' size with an even brightness with a slightly brighter core. Definitely need to re-observe this system with larger aperture.
Arp 294 NGCs 3786 & 8 Mark 744 - 3786 m12.3 sb 14.5 2.1'x1.1' SAB(rs)a/p - 3788 m12.6 sb 13.4 1.8'x.5'SAB(rs)ab/p 11h39.8m +31°54.1'. Arp Classification - Double Galaxies with long filaments. With the 16" at 233x, a nice pair, touching at the ENE end of 3786 and the S end of 3788. 3786 oval, 1'x.5' in size with a bright stellar core fading quickly to an even haze. Smaller than it's specification, but deep photo from the Arp Atlas shows very faint surrounding nebulosity extending to 2' diameter. 3788 is larger of the two visually, about 1.7'x.4' aligned NS. Magnitude 10.5 field star 2' to SE prevents any detection of the faint nebulosity surrounding 3786.
Arp 313 NGCs 3991, 4 & 5 - 3991 m13.1 sb 12.2 1.3'x.3' Im/p - 3994 m12.7 sb 12.2 .9'x.5' SA(r)c/p - 3995 m12.4 sb 13.7 2.6'x.9' SB/p 11h57.8m +32°17.2'. Arp Classification - Groups of galaxies. 16" at 233x, barred spiral 2.5'x1' with bright non-stellar core. There is a .5' bar aligned EW with thick bright arms extending north and south from the ends. 3994 is about 2' to the SW PA 240°, a small oval about .8'x.4' in size with a slightly brighter core region. 3991 lies 3.5' to the NW of this pair, a thick streak 1.2'x.3' aligned NE-SW. You have to keep SAO 62774, 5' to the ESE out of the field to see any detail. IC 2979 is 15' to the SW of this triple system, very faint in the field.
Arp 336 - NGC 2685 m11.3 sb 12.6 4.6'x2.1' SBO/p 8h55.7m +58°44'. There is no Arp classification for the last six objects in the atlas, but this one looks as if it would fit into the "interacting double galaxies" class. By the redshift published for this system, 997 kps corrected for the CMB, this is the nearest and brightest polar ring galaxy. That redshift implies that this system is at 2/3 the distance of the Virgo cluster, around 35-40 MLY. I looked at the MAST web site and found Hubble images taken in 1998 and 1999 of 2685, and it is not resolved into stars. This is a case wherein the redshift indicates that the galaxy is much nearer than it actually is. In the 20" at 423x 2685 is a spindle shaped object 2'x.5' aligned NE-SW. It has a bright core region that is .5'x.3' in size. There is a bright field star located 2.5' N of the core. On the side of the galaxy towards that field star there were occasional dark contrast features that would cross the plane of 2685. There is a very faint half oval brightening of the field about 1' in length at right angles to the system on the NW side of the galaxy.
Arp 26 - M101 and Arp 337 - M82 are the two brightest Arp galaxies in Ursa Major. They have been observed innumerable times by many many observers, photographed zillions of times by others, so I won't bore you with yet another description of these two. I will say that after trying to tease detail out of some of the other Arp galaxies in UMa (there are 34 Arp galaxies and galaxy groups in UMa of which I have observed 20 thus far) swinging your scope over to these two will make you fear for your dark adaptation. Arp 85 - M51 - in Canes Venatici falls into this same category. But to continue in Canes...
|Arp 23 NGCs 4618 & 25 - 4618 m10.8 sb 12.9 4.2'x3.4' SB - 4625 m12.4 sb 14.5 2.3'x1.9' SB/p 12h41.6m +41°8.5'. Arp Classification - Spiral galaxy with one arm. 16" at 233x 4618 is a large oval 4'x3' in size elongated NS. There is a bright bar on the N side of the system aligned NE-SW about 1' in length with a brighter non-stellar core region. A thick arm is attached to the E end of the bar, wrapping around to the south. The arm has a mottled appearance. In the catalogs it appears that this system at one time had three different IC numbers attached to it, 3667 for the core region, and 3668 & 9 attached to two of the brighter star clouds in the arm. 4625 lies 8' to the NNE at PA 30°. It is much dimmer with an even brightness 2' diameter circular appearance. It has an offset nucleus in the northern portion of the galaxy that is slightly brighter than the rest of the system.|
Arp 84 NGCs 5395 & 4 - 5395 m11.4 sb 13.5 2.7'x1.3' SA(s)b/p - 5394 m13 sb 14.4 1.7'x.8' SB(s)b/p 13h58.7m +37°25.1'. Arp Classification - Spiral with large bright surface brightness companion on arms. 16" at 233x, 5395 is a large oval 2.5'x1.2' aligned NS. It has a bright compact non-stellar core with thick spiral arms. The arm on the north and east fades away in about 90°. The one that winds around from the south to the west extends to within about 1' from the nucleus of 5394. 5394 is small, about .6-.7' in diameter, even brightness and circular. With averted vision there were signs of an extremely faint arm extending from the core to the near arm of 5395, although this was more of a teaser than a concrete sighting.
Arp 266 NGC 4861 - m12.3 sb 15.9 3.3'x1.5' SB(s)m 12h59.1m +34°51.3'. Arp Classification - Galaxy with irregular clumps. 16" at 233x 4861 is 2.6'x.4' in size aligned NNE in PA 25°. There is a bright nucleus at the SW end with a bright round .2' nebulosity surrounding it. There is a haze approximately 2.5'x.3' stretching to a m12.9 star at the NW end. The star and nucleus are fairly close in brightness, the haze between is clumpy in appearance, the whole thing looking kind of like a small transparent guppy, with more clumpiness towards the end with the nucleus.
Arp 269 NGCs 4490 & 85 - 4490 m9.8 sb 11.9 6.4'x3.2' SB(s)d/p 4485 m11.9 sb 13.9 2.4'x1.8' IB(s)m/p 12h30.7m +41°37.9'. Arp Classification - Double galaxies with connected arms. This system has been on my favorite observing target list for a long time, with the fan-like spray of short arms coming off either end of 4490 being an awe-inspiring sight in larger apertures. 4485 hanging above the NW end of 90 is just icing on the cake. It is easy to find, lying just 40' NW of Beta CVn. For 25" and larger scopes, this target will match any of the other "tourist attraction" targets at your next star party.
And again, there are other Arp targets in Canes, but we have a bit more of the springtime skies to cover, so for this first installment, I am just covering some of the highlights. So, moving on to Coma Berenices...
|Arp 34 NGCs 4613, 14 & 15 - 4613 m15.5 sb 13.8 .4'x.4' Sa/p - 4614 m13.3 sb 14.3 1'x.9' SB0/a - 4615 m13.1 sb 13.8 1.6'x.7' Scd 12h41.7m +26°4.5'. Arp Classification - Integral sign spiral galaxy. This classification applies to 4615 only, but you cannot observe it without observing the other two, so they got included. 16" at 233x, 4615 is small, faint, elongated NW-SE about 1'x.4' in size. 4614 is 2' SW from 15, small slightly brighter, elongated NW-SE .4'x.2' in size. 4613 lies 2' NW of 15, small very faint circular haze seen with averted vision only. The core region was brighter than the rest of this very small galaxy, but not by much.|
Arp 163 NGC 4670 - m12.7 sb 13.6 1.4'x1.2' SB0/a/p 12h45.3m +27°7.1'. Arp Classification - Galaxy with diffuse counter tail. 16" at 233x, small bright nucleus fading to .5' diameter round central area with extensions to either side oriented EW. These "ears" extended the object to about 1' in width. Reminded me of the Saturn Nebula, with its ansae on either side.
Arp 242 NGCs 4676A & B the Mice - 4676A m14.1 sb 14.7 2.6'x.5' S0/p - 4676B m14.1 sb 14.6 2.3'x1.2' SB0a/p 12h46.2m +30°49'. Arp Classification - Galaxies with appearance of fission. 16" at 175x (this night had too many light gusty winds to support any higher power on this object.) A pair of faint compact objects, each about .5'x.3' in size. Both have bright stellar cores, with the object to the NW showing the "tail" with averted vision. The aforementioned wind gusts jiggling the scope made the tail surprisingly easy to detect. It stretched due north from 4676A for about 1.5', but there was no sign of the faint nebulosity around the B component.
And now to Leo Minor...
Arp 270 NGCs 3395 & 6 - 3395 m12.1 sb 12.3 1.8'x1.6' SABcd/p - 3396 m12.1 sb 13.6 4.2'x1.4' IBm/p 10h49.8m +32°59. Arp Classification - Double galaxy connected arms. 16" at 233x 3395 oval 1.6'x1.3' aligned NE-SW with irregular outline. Even brightness, possibly a little brighter in core region. Joined at NE end to 3396, 1.5'x1', rectangular in shape, aligned EW brighter in first 1' after join.
And in Leo ...
Arp 63 - NGC 2944 m14 sb 13.7 1'x.4' Sc/p 9h39.4m +32°18'. Arp Classification - Spiral with small high surface brightness companion on arm. In the 16" at 263x this is a small thin edge on object about 1' in length elongated EW with a brighter non-stellar nucleus. It appears slightly wider on the W end with a second stellar nucleus at the tip of 2944's lens. There would be an occasional very dim almost stellar point appear about 30" S of the E end at the position where MegaStar plots KUG 936+325B. 4' to the NNE of 2944 is the galaxy pair MCG +6-21-71 and +6-21-72, AKA Arp 129. At mag 16 and 13 respectively, this would seem to be a difficult pair, but they were easily seen as a pair of nucleii separated by 30" sharing a common envelope.
Arp 94 NGCs 3226 & 7 - 3227 m10.3 sb 13.7 6.6'x5' SAB(s)a/p - 3226 m11.4 sb 13.3 2.5'x2.2' E2/p 10h23.5m +19°53.5'. Arp Classification - Spiral galaxy with E galaxy on arm. Pretty pair, Leo's version of M51. 16" at 233x, 3227 is large bright oval with a very bright stellar core surrounded by a central oval 2.3'x1' in size with faint arms looping tightly around for another 1' to 1.5' around the core region. Aligned SW-NW. 3226 is attached to the NW end of 3227, a dimmer round object 2' in diameter increasing in brightness to a stellar core. There is a faint haze of nebulosity surrounding both galaxies.
Arp 232 NGCs 2911 & 12 - 2911 m11.5 sb 14.1 4'x3.1' S0/p 2912 m12? sb 12? 9h33.8m +10°8.8'. Arp Classification - Galaxies with appearance of fission. 16" at 233x, 2911 is a large round haze about 2.5' in diameter with a gradual slight brightening towards the nucleus. 2912 was much easier to see, a small bright non-stellar object embedded in the haze of 2911 about 1' ENE, PA 70° from the core of 11.
Arp 316 NGCs 3190, 3187, 3185, and 3193 - Hickson 44 - 3190 m11.1 sb 11.1 4'x1.5' SA(s)a/p - 3187 m13.4 sb 13.9 2.9'x1.2' SB(s)c/p - 3185 m12.2 sb 13.3 2.1'x1.4' (R)SB(r)a - 3193 m10.9 sb 12.2 2.9'x2.8' E2 10h18.2m +21°49.6'. Arp Classification - Groups of galaxies. This is another long time favorite, it is one of the objects that I use to judge sky brightness, transparency and other seeing conditions. In a 12.5" dob under mag 4.5 skies I can only make out 3190 and 93. Under darker skies with poor seeing, I can see all but 87. Under good skies with larger apertures (20" and up) this group really shines. 16" at 262x 3190, an almost edge-on spiral, starts showing its dust lane. In moments of good seeing you can just make out the curving kinks it makes at the NW end. 3187 is aligned perfectly with 90, 3' to the NW at PA 300°. Both galaxies are at this same PA in their orientation. 87 is a face on barred spiral, the bar about 1.2' in length, with no trace of a core. Extremely faint arms head off at right angles on either end of the bar. 3185 lies 11' SW of 90, another face on barred spiral with a faint bar about the same length as 3187's bar, and with the same orientation. It has a brighter non-stellar core, and the whole system is surrounded by a faint ring of faint arms, making it one of the theta shaped SB galaxies. 3193 lies 6" NE of 90 in PA 45°, a bright round 2' in diameter system with a bright non-stellar core. With a lower power eyepiece with at least a 25' FOV, you can see quite a variety of galactic morphology in one field of view. And to top it all off, throw a bright supernova in 3190 (2002bo this last springtime, about 30" away from the core on the opposite side from 87), and you get a field that is hard to beat.
Arp 317 M65, 66 and NGC 3628 - AKA the Leo Trio. M65 m9.3 sb 12.3 9.5'x2.3' SAB(rs)a - M66 Arp 16 m8.9 sb11.8 9'x4.2' SAB(s)b - 3628 m9.5 sb14.7 15.5'x4.3' Sb/p 11h20.3m +12°59.3'. Arp Classifications - Arp 16, M66 - Spiral galaxy with detached segments - Arp 317, the Trio - Groups of galaxies. You can give yourself another rest from straining your eyes with these. Dark adaptation is another story. M66 has always been a beautiful target in any size telescope. I can see it from town under mag 4.5 skies with a 120mm Chinese refractor at 40x, but all I can do is detect it. For the really nice detail, dark skies and large aperture are the only way to go. 16" at 300x (7 Nagler), large bright core region brightening to a very bright non-stellar core. Arms and dust lanes are readily visible, especially the arm that is extended to the south, tapering to a point. Both 65 and 66 are aligned almost exactly NS, with 66 due south from 3628, 35' to the north. 3628 is an interesting edge-on spiral with a very prominent dust lane. It starts spreading out about 5' from the center in each direction, and the stellar swarm, rather than tapering to a point like most edge-ons, spreads out to about 4' width at each end.
Arp 320 - Copelands Septet - NGCs 3745, 3746, 3748, 3750, 3751, 3753, 3754 and PGC 36010 - 3745 m15.2 sb 12.8 .4'x.2' E-SO - 3746 m14.2 sb 13.7 1.1'x.5' SBabR - 3748 m14.8 sb 13.1 .7'x.4' SO - 3750 m13.9 sb 13.1 .8'x.7' E-SO - 3751 m13.9 sb 12.5 .8'x.5' E-SO - 3753 m13.6 sb 14.2 1.7'x.5' Sab - 3754 m14.3 sb 12.1 .4'x.3' Sb 11h37.9m +21°58'. Arp Classification - Groups of galaxies. This group, with the addition of PGC 36010, comprise Hickson 57. In the 16" at 262x all I can say is wow! In a slightly over 7' field I counted 9 galaxies. This included MAC 1137+2202 at the NW end of the group. This galaxy is 2.5' NW of a subgroup of 4 objects, 3745, 46, 48 and PGC 36010. 3745 is a small oval of .4'x.2' in size with a brighter core region. 3746 is .7' S with an oval core area .4'x.2' with a faint haze extending NW and SE from the core. 3748 is 1.2' E of 3745, and is a small oval .4'x.3' in size with a slightly brighter core area. PGC 36010 is a very dim stellar point .9' S of 3748. 2' SE of these four is a tight grouping aligned NE-SW consisting of 3754, 53 and 50. 3754 is a small .4'x.3' oval aligned NS and is the brightest object in the group. It is just N of the core region of 3753, a WNW-ESE streak about 1.2'x.4' in size. The ESE end extends further than the other, giving it an unbalanced appearance. About .6' SW of 3753 is 3750, a small round .5' diameter galaxy with a bright almost stellar core. 3751 is 2' S from these three, an oval object aligned NS .7'x.5' in size. All in all, a very nice field.
In Virgo, several Messier objects are also Arp galaxies, M49 Arp 134, M60 Arp 116, M87 Arp 152, and M90 Arp 76. I don't have much to say about these that hasn't been said by many others, when I finally bag the jet in M87 I will talk about it then, but I will briefly mention M90. M90 in itself is a beautiful object, but have you noticed a faint bit of fluff located about 6' N of its core? This is IC 3583, m13.3 that is a bit of an eye teaser when you have the bright M90 in the field. It is a Magellanic barred irregular that is at a distance of about the same as the LMC from the Milky Way. Also in Virgo...
|Arp 274 NGC 5679. NGC is a very small object, about 1.2'x.5' that is actually a triple system. Its Arp Classification is galaxies with loops. It is also interesting in that in the image from the Arp Atlas the B component, in the center, shows signs of interacting with the A component. This is yet another system where the redshifts of the objects show them to be at drastically different distances, but they are in obvious contact. RV for the three components are - A 7483kps, B 8654kps and C 7618kps. By conventional theory A and C are fairly close, but B should be a background object, anywhere from 17 to 23 Mpc in the background. This is the distance from us to the main Virgo cluster, so how is there interaction? (When I get to the fall objects, you will see that the conventional explanation for Stephen's Quintet suffers from a similar misinterpretation. Hint, look up the redshifts of the obviously interacting pair, not the foreground galaxy.) Anyway, in the 16" at 262x, component B is the brightest, with a bright core and very faint arms. Component A has a bright core with very very faint arms. Component C is a small faint oval elongated NS.|
I hope that my observations have whetted your interest in these peculiar galaxies. They are a small sample from an Atlas containing 338 very interesting objects. I look forward to sharing with you some of the other interesting sights that I have enjoyed in my voyage of discovery. I know that I have skipped some of the Springtime constellations and their objects, but I promise you that I will make up for that in the near future. I have tried to present a range of targets, from bright to challenging, that covers a fair sample of the type of objects that you can expect to see in this interesting Atlas. I am very much enjoying the challenge, the research into these galaxies, the several books and publications that Dr. Arp has given us, and I am looking forward to continuing this voyage. I leave you with these last thoughts. Always examine your assumptions, the things that you know. There is where we find our errors. And finally... think peculiar.