NGC0637

NGC 637 is a small, tight, open cluster in Cassiopeia west of the Soul and Heart Nebulae. It is in the original Herschel 400 observing list and was discovered by William Herschel on November 9, 1787. According to WEBDA, it is about 7000 light-years distant and only about 9.5 million years old, a very young cluster. It is listed as Trumpler class I2m meaning it is highly concentrated with a medium range of brightness and richness. My visual log indicates I needed fairly high power to see 5 or 6 of the brighter stars against a faint fuzzy background of a dozen or so faint stars. Not much to look at I ventured. But it is one that easily fits my rather small field of view.

One paper ( http://arxiv.org/pdf/1105.3121v1.pdf ) on it notes it is one of 6 open clusters rich in Beta Cephei stars. These are stars that are variable due to the "kappa mechanism" with an iron caused "Z bump". Here's how Wikipedia explains the "kappa mechanism."

"In a normal star, an increase in compression of the atmosphere causes an increase in temperature and density; this produces a decrease in the opacity of the atmosphere, allowing heat energy to escape more rapidly. The result is an equilibrium condition where temperature and pressure are maintained in a balance. However, in cases where the opacity increases with temperature, the atmosphere becomes unstable against pulsations. If a layer of a stellar atmosphere moves inward, it becomes denser and more opaque, causing heat flow to be checked. In return, this heat increase causes a build-up of pressure that pushes the layer back out again. The result is a cyclic process as the layer repeatedly moves inward and then is forced back out again."

The cluster was discovered by William Herschel on November 9, 1787. It is in the original H400 program. My log from July 14, 1985 with my 10" f/5 at 80x on a good night but hurt by aurora reads: "A small tight cluster of 5 bright and a dozen faint stars. How could the writer see 20 stars in a 6" when I couldn't see that many in a 10" at any power much less the 43 he used. That's too little to even resolve this tight cluster. I needed 80 to do it. Is he copying from Burnham's?" Note I was working from a preliminary copy. How it changed by final printing I don't know.

While many stars vary by this means often this is due to hydrogen or helium ionization. In the case of Beta Cephi stars, it is due to iron at a depth creating a temperature of 200,000K.

The 2MASS lists 6 faint, star-like galaxies in the image. They are so difficult to see and impossible to tell from stars visually that I didn't bother with an annotated image.

Due to clouds, I started color one night of less than good seeing but soon was clouded out. I tried another night of better seeing and got the last two red frames. But when I went to collect luminance data I was shut down after only one frame due to clouds. Somehow I never went back. So I used all frames to make a pseudo luminance frame and processed the color frames normally. With little luminance, this one doesn't go as deep as usual but is plenty sufficient for this cluster. If seeing had been better for the blue and green frames I'd have just made an RGB image but that was too fuzzy. Adding the one much sharper luminance frame and two red frames sharpened the stars considerably. I considered using only those three for the luminance but even though adding the other 4 made for slightly fuzzier stars some deconvolution helped considerably so I went with using all 7 to make the pseudo luminance frame.

14" LX200R @ f/10, Pseudo L=1Lx10'+RGB2x10'each color RGB=2x10', STL-11000XM, Paramount ME

Related Designations for NGC0637

NGC0654

NGC 654 is an open cluster about in Cassiopeia about 6650 light years distant per WEBDA though I've seen a lot of undocumented estimates of 7800 to 7900 light-years away and one that put it only 5200 light-years away. The large dark nebula to the upper left is LDN 1337. The smaller one at the top just right of center is LDN 1332. The blue reflection nebula around the star BD+61 315 at the southwest corner of the cluster is vdB 6 aka GN 01.40.6. The cluster was discovered by Caroline Herschel on September 27, 1783. William didn't record it until November 3, 1787.

I was quite surprised how many images of this cluster I found on the net that didn't show either the reflection nebula nor the dark nebula except very faintly. Most showed the cluster against a dark background rather the dust field it is in. One of the few that do show these features and very well is Tom Davis' wide field image. In fact, I think it is what caused me to put this one on my to-do list or at least move it to the front of the list. http://tvdavisastropics.com/astroimages-1_000094.htm.

This image illustrates what I call the f ratio myth. Those who believe the myth would say at f/10 imaging such faint dust as in this image would take many days with a total of maybe 40 to 80 hours exposure time, not one hour ten minutes I used. Low f ratio usually means a nice wide field of view but isn't necessarily "faster" as many claim. It all depends on aperture, image scale and the signal to noise ratio you find acceptable. Notice F ratio isn't a factor though it does have a say in the image scale factor.

There is a spear of blue light coming in from the top right of center. That's a reflection from a bright star hitting the edge of something (chip?) in the camera and is not a real feature. A fainter one is at the top left of center.

14" LX200R @ f/10, L=4x10' RGB=1x10'x3, STL-11000XM, Paramount ME

Related Designations for NGC0654

NGC0659

NGC 659 is an open cluster in Cassiopeia. The WEBDA says it is about 6,300 light-years away though many internet sources say it about 10,000 to 11,400 light-years away without giving a source. Its diameter is about 5 minutes of arc which translates to a diameter of about 15 to 17 light-years using the larger distance, 9 light-years using the 6,300 figure. The cluster's age is difficult to pin down but it is likely about 112 million years old. For more on this see:
http://www.springerlink.com/content/q263568660312q37/

The cluster was found by Caroline Herschel in on September 27, 1783. William verified it 4 years later.

14" LX200R @ f/10, L=4x10' RGB=1x10'x3, STL-11000XM, Paramount ME

Related Designations for NGC0659

NGC0660

IC 148 is a rather small blue, warped, disk galaxy in Pisces only 22 minutes of arc from the far more famous polar ring galaxy NGC 660. Just too far for me to put them in the same FOV. They do have similar redshift so are likely related and maybe even interacting. It may be the cause of the warping of this galaxy. The distance to it is rather uncertain. Even APOD won't try to pin that down for NGC 660 saying only that it is over 20 million light-years from us. Redshift puts IC 148 at 22 million light-years while a single Tully Fisher estimate says 35 million light-years. I tend to favor the larger value mainly due to its angular size. If the 22 million light-year figure is used the galaxy is only 22,400 light-years across. That seems small to me. The larger distance makes it 35,600 light-years across, a more reasonable size. If its angular separation from NGC 660 is a good indicator of their real separation, that is they really are at the same distance from us, then they are only 139 thousand light-years to 221 thousand light-years apart. That's quite close. This, of course, is the minimum distance between them, the actual distance could be much greater since neither has a good distance estimate.

NED classifies it in one place as Sc(f) and Im another. The latter could be consistent with the smaller size and nearer distance while the former gives it about the same size as M33 which fits its classification better. In case you are wondering the (f) is from the Yerkes classification system and means it has prominent F type stars. This helps explain its rather blue color.

The annotated image shows a surprising number of quasars and quasar candidates (labeled UvES in the annotated image). The one asteroid is identified in the annotated image.

After writing the above I checked my image of NGC 660 taken in 2009 using generation 1 filters rather than generation 2 used for the IC 148 image. There was a small amount of overlap. My processing methods have changed greatly since 2009 so it is processed much differently. Rather than take the time to reprocess the 2009 image I did a quick rework to sort of match the two into one large 2705x2464 mosaic at 1" per pixel. Due to the small overlap of only stars the processing differences aren't very noticeable. It does show the relationship between these two galaxies. To do it right I need to retake NGC 660 with today's optical train (even that has changed slightly) and process them the same. I don't see that happening however. Thank goodness for RegiStar that managed to match the two with only a very small overlap between the two and slightly different image scales and distortions at the edges where they meet.

Data for the IC 148 image:
14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME
Data for the NGC 660 image is the same but for some reason the blue channel used three 10 minute images rather than 2 used for the other color channels.

Related Designations for NGC0660

NGC0663

NGC 663 is an open cluster in Cassiopeia. It made my list by being a Herschel 400 object from his first list. My log entry, from July 14, 1985, right after I'd noted a nearby tiny open cluster NGC 659 which I imaged back on November 3, 2010, reads: "Large, scattered cluster of more than 50 stars. A very good cluster after all the small, tight, faint ones on the list." That last bit a reference to NGC 659. Most sources credit the cluster with some 400 stars rather than the 50 I estimated visually in my 10" f/5 scope.

So why did it take so long for me to get this one right near the small one? The answer is it didn't. I took NGC 663 on November 9, 2010, less than a week later. Yep, I did it again. In yet another sweep of the hard drive, I turned up yet another lost object! I spent hours making sure I'd finally found them all last time and now this one pops up. I wasn't even looking for lost files. Instead, I was verifying all had been backed up and this one wasn't on the backup drive but was on both the hard drive of the imaging computer from 2010, no longer being used, and on my processing computer but not in the "to process" log. That explains how it got lost. William Herschel discovered it on November 3, 1787. I almost took it on the 223rd anniversary of its discovery. My log entry from the first H400 program using my 10" f/5 at 60x on an average night hurt by an aurora reads: "Large, scattered cluster of more than 50 stars. Best seen in 10x50 binoculars or at very low power in a 60mm refractor. It's just lost in a 10" telescope.

Anyway looking up the cluster I find some disagreement. WEBDA puts it at 6360 light-years distant and about 16 million years of age. Various sources at Wikipedia say it is 6850 light-years away and 20 to 25 million years old. Not all that major of a disagreement. Still for how well studied it is I'd expect better agreement.

The cluster is also known as Caldwell 10 and is sometimes claimed to be visible naked eye though its listed magnitude is 7.1. It is thought to have formed in the Cassiopeia OB8 association. It has an unusual number of Be stars. Also, three blue stragglers have been found in it. These are the result of stars merging, a rather rare event in open clusters.

This was taken back when I binned my color data which I don't do today. Not because I didn't like the result be because it allows me to use color data to augment luminance when conditions make that necessary. I also took only half my color data. Something I still sometimes do with bright open clusters like this one with no galaxies in the background and no asteroids to remove.

A check of NED shows no galaxies listed. SIMBAD notes the Be stars I mentioned but little else. Since they appear the same as any other star, maybe slightly less blue, I didn't bother to annotate them. It would have made for a rather tightly packed image needing many lines pointing to the various stars. Those interested can plate solve the image with Astrometry.net and look them up in SIMBAD.

WEBDA indicates the cluster is rather significantly reddened by .78 magnitudes (that is almost exactly a factor of 2) which explains why the many B stars are rather white rather than blue as you'd normally expect. I see a lot of images online with very blue stars for this cluster. I can only surmise they pushed the blue to achieve that.

14" LX200R @ f/10, L=4x10'x2 RGB=1x10'x3, STL-11000XM, Paramount ME

Related Designations for NGC0663

NGC0664

The NGC 664 galaxy group is located in the southeastern corner of Pisces about 240 million light-years distant. NED says there are 6 in the group but I find only 4 in my image at the right distance. I was unable to determine where the other two are. The four I imaged are NGC 664, IC 150, PGC 006329 and tiny NSA 130250. NGC 664 is almost 100,000 light-years across while NSA 130250 is only 10,000 light-years long. NGC 664 was discovered by John Herschel on September 24, 1830. IC 150 was found by Stephane Javelle on December 5, 1893.

The asteroid (2682) Soromundi photobombed my image. While the Minor Planet Center said the citation info was unavailable being behind a copyright I found the copyright info in Google Books. It reads "Discovered by E.F Helin and S.J. Bus June 28, 1979. Named by Helin in honor of the Los Angeles Chapter of the YWCA 'sisters of the world'." Google translates the word Soromuni in Latin to "sisters of the world". When I simply "googled" the term I got back dozens of references to a lesbian chorus by that name. I had to dig many pages down to find the Google Books reference.

This field is only 6 degrees north of the ecliptic so I expected many asteroids but only the one appeared. Though a plane with its bright lights and strobe flew through one of my two red frames it was easy to remove using the other red frame for that part of the color data. That's why I take two unless I'm around to see the frames as they come in.

Since the frame is near the Zone of Avoidance there was little information on the field. Most galaxies carried only positional names, often from very obscure catalogs. So most are just noted with a G for galaxy along with its redshift distance.

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



http://www.mantrapskies.com/image-archive/NGC/NGC0664_IC0150_PGC6329/PGC6329L4X10RGB2X10.JPG
http://www.mantrapskies.com/image-archive/NGC/NGC0664_IC0150_PGC6329/PGC6329L4X10RGB2X10CROP.JPG
http://www.mantrapskies.com/image-archive/NGC/NGC0664_IC0150_PGC6329/PGC6329L4X10RGB2X10ID.JPG

Related Designations for NGC0664

NGC0669

NGC 669 is a rather red and dead spiral in northwestern Triangulum. In fact, the top third of the image is in Andromeda. It's located on the southwest corner of the Abell 262 galaxy cluster the core of which is sometimes known as "The Fath". Its redshift distance of 200 million light-years is within the range of redshifts seen for this cluster which is put at 220 million light-years. Tully-Fisher measurements put its distance at 250 million light-years but some of the papers indicate they had to make some rotation rate fudges due to a weak signal from Ha sources so these readings may be off. The red and dead idea is supported by cold hydrogen data from radio telescopes. The galaxy is surrounded by a very large but very diffuse cloud of cold hydrogen. Hot hydrogen as evidenced by H alpha emission is also very weak. It appears much of its star building hydrogen has been thrown out of the galaxy. This could explain the lack of current star formation. The galaxy isn't distorted as if it had a major interaction to cause this but it may have been so long ago things are back to normal now but for the lack of star formation. Some of the red color may also be due to dust kicked out of the galaxy that is reddening it. Though I found nothing on this, just an idea I had. It also has an odd dust cloud along the rather dense dark lane which may be left over from some long-ago interaction. If part of the Abell cluster it doesn't lack for candidates now well out of my field. The galaxy was discovered by Édouard Stephan on November 28, 1883. The galaxy is huge for a spiral with a diameter of about 185,000 light-years by my measurement. If the Tully-Fisher determination is right then it is 230,000 light-years across. Another reason to doubt that measurement.

The galaxy is listed in the 2 micron flat galaxy catalog. While not seen edge on the core region does give the appearance of being very flat. I suppose that is what allowed it to make the catalog as there's no optical evidence of a central bulge, just a very small and not all that bright core. Usually, the bright core would be much larger and hide much of the far side of the galaxy due to its bulge. Thus if seen edge on this would likely be a very thin galaxy. Two other anonymous thin galaxies are in the image. One to the northwest and another possibly more distant one to the north-northeast.

To the southeast is the double galaxy of UGC 01258. They appear connected by a tidal stream and neither has much structure left, if they had any, to begin with. The southern and brighter part has a redshift that puts it at 190 million light-years so it too could be part of the Abell 262 cluster and likely related to NGC 669. Oddly the fainter northern galaxy is at the position the PGC has for this pair. I'd have expected the position to be between the two as it is for the UGC 1258 designation. The pair cover a projected distance of about 70,000 light-years. Assuming each ends in the middle of the tidal stream the northern galaxy is 28,000 light-years in size and the lower 42,000 light-years across.

The only other galaxy in the frame with redshift distance is [WGB2006] 014400+34320_e off the northeastern end of NGC 669 but at a distance of 1.3 billion light-years. It is about 80,000 light-years in size. I suspect several more of the galaxies in the image such as LEDA 3088490 is a member of the Abell 262 cluster but without redshift data that is only a guess.

The night I took this was very hazy causing nasty halos around even the fainter stars. I tried reducing the halos but that seems to have caused some stars to elongate in various directions probably due to where the haze halo was the brightest. I'm not sure it was worth the effort.

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

Related Designations for NGC0669

NGC0674

NGC 697/674 is a spiral galaxy in northwestern Ares about 130 million light-years distant by redshift and 110 by the consensus of 17 non-redshift measurements at NED. It is considered a member of the NGC 691 galaxy group which average about the same redshift as that of this galaxy. Still, it is hard to argue with a rather nicely grouped non-redshift measurements that have a standard deviation of only 9 million light-years. So I'll split the difference and say 120 million light-years. That makes its size nearly 200,000 light-years including faint plumes my horrid night barely showed. Unfortunately, they don't show in the color image. Using the size seen in the posted image it is still very large at a bit under 160,0000 light-years across. So this is a major galaxy. While I've not yet taken NGC 691 its angular size in catalogs is smaller than NGC 697-74. NGC 697 is classified as SAB(r)c: by NED and the NGC Project and Seligman. It's unusual when those three agree though Seligman uses a question mark for a colon they two mean essentially the same, a bit of doubt in the classification as a c arm structure galaxy. Not surprising given the oblique angle we see it at. For a hint of the plume, especially on the east side see http://cseligman.com/text/atlas/ngc674wide.jpg.

So why two NGC listings. Seems William Herschel discovered it on September 15, 1784, got its position correct and earned the NGC 697 entry from Dreyer when he assembled what became the NGC catalog. Then on December 2, 1861, yes, over 77 years later Henrich d'Arrest recorded a galaxy 2 minutes of arc west of NGC 697 which he claimed to have viewed the same night. But there's nothing he could have seen at that position. Also, his description is a perfect match, including the position of a 9th magnitude star in relation to the galaxy, for NGC 697. Thus the two are now considered one and the same by nearly all catalogs. You can read a bit more on this mix-up at the NGC Project webpage for either NGC 697 or NGC 674. While Herschel discovered it the galaxy isn't in either of the H400 observing programs.

The night I took this image had awful seeing and even worse transparency due to a nasty haze layer. Sometimes these stabilize seeing but not this night. The 6th magnitude star in the lower left corner SAO 74966, a double star whose combined light is that of a G3III star so virtually white with a tinge of red, gave me fits sending a bright gradient completely across the frame. Combined with the loss due to lousy transparency this image is about 2 magnitudes short of my normal efforts with an FWHM of 4" rather than the 2.5" I often obtain for stars. Thus much detail in the galaxy was lost. Taken in late January 2017 it was my last January or February image. It is now well into March with a bright moon as I write this with still no imaging. Worst winter I've ever had for imaging.

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

Related Designations for NGC0674

NGC0678

NGC 678 and 680 are a rather interesting pair of odd galaxies in Aries about 116-7 million light-years away. They are part of a larger group that includes NGC 691 I thought I'd captured but see it was just out of the image at the bottom left. I need to redo this one with the field centered 5 minutes south of the position I used. All three are rather odd galaxies.

NGC 678 is a near edge on spiral classed as SB(s)b: sp. The dust lane is rather odd in that it runs along or slightly below the major part of the western arm but above the less distinct eastern arm. The dust lane seems to curve around the core rather than run straight across it as dust lanes usually do. A second short, fine, faint dust lane runs below the eastern dust lane. Both arms, but especially the eastern one seem to have plumes of stars that have been drawn out of the disk. I need to redo this with more time to see more of these plumes.

NGC 680 is the other NGC galaxy in the image. It is classed as E+ pec. It appears to be a multishell elliptical galaxy. But note the faint hint of an arm running from the core, through the shells to the outer edge a the one o'clock position. An even fainter one runs down and to the right from the five o'clock position. Shell galaxies are considered the result of mergers still in the process of settling down to be normal elliptical galaxies.

IC 1730 shares about the same redshift as the two NGC galaxies so is part of their local group. It is the S0-like galaxy to the northeast of NGC 680. NED makes no attempt to classify it. Nor could I find much on it. Of the three it is the only one that appears rather normal. Obviously, it is a much smaller galaxy than the other two.

NGC 678 and NGC 680 were discovered on September 15, 1784. Neither are in the H400 observing programs. IC 1730 was discovered by Stephane Javelle on January 17, 1896.

Nothing else in the image has any redshift values so I didn't prepare an annotated image. In fact, only a handful of other galaxies in the image are even cataloged at NED. This will change when the latest Sloan data is merged into their database.

As mentioned, I just missed picking up NGC 691, an SA(rs)bc spiral that is rather lopsided in that the western side is brighter than the eastern side. And if I'd have moved everything west about 5 minutes I'd have picked up IC 167. Those with a much wider field of view can pick up NGC 697 as well. NGC 697 has a nicely wrapped eastern arm but the western one is drawn out quite a bit so doesn't wrap around as it "should."

While I'd meant to capture at least NGC 691 all is not lost. As it happens IC 167 is Arp 31. So one of the strange galaxies in this related group did make his atlas. I captured NGC 691 while imaging Arp 31.

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

Related Designations for NGC0678

NGC0681

NGC 681 is another Sombrero Galaxy, at least in appearance. It is located in Cetus about .6 degrees west of Zeta. It's distance seems rather uncertain. I found no two sites giving the same distance. NED shows a redshift distance of 69 million light-years but a non redshift distance of 140 million light-years, twice as far away. The best agreement among sites I checked come in at about 75 to 80 million light-years. I'll say 77.5 million light-years to pick a value in the middle. Using at I get a diameter of 62,000 light-years. The real Sombrero Galaxy, M104, has a size of about twice that, 130,000 light-years. So it is a little imposter. It was discovered by William Herschel on November 28, 1785 but isn't in either of the H400 observing programs. Nor could I find I'd logged it in my many years of visual observing. Though it should have been a rather easy object in my 10" f/5.

Conditions were poor the night I took this with a very bright sky costing me to lose about 1.5 magnitudes. Thus if I had better data I could stretch much further I suspect it's halo, like that of M104 would be considerably larger than I captured here. Though looking at what few images of this one I found on line none seemed to show any more halo than I do here.

It appears to have a true companion, PGC 6637 to the northwest. At least its redshift is rather similar. It is a rather featureless S0 galaxy that I measure at about 30,000 light-years in size assuming it is at the same distance as NGC 681. All other galaxies in my image that NED had redshift data on were much more distant. Two were over 4 billion light-years distant, even further than one of the two quasars in the image.

The annotated image shows all other galaxies in the field that NED had redshift data for.

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

Rick

Related Designations for NGC0681