NGC7146

NGC 7146 and 7147 are the largest of the three galaxies in the WBL 672 galaxy group about 400 million light-years from us in southwestern Pegasus. Both appear to be red and dead spirals. Spirals that aren't making new stars in any significant amounts so all the hot blue stars that normally define spiral arms are long gone. Both are barred galaxies. Both were discovered on August 11, 1863 by Albert Marth being number 456 and 457 in his list.

The only blue galaxy in the group is CGCG 376-046. NED doesn't classify it, not even as a spiral which it obviously is. More confusing is that it is listed as a double galaxy. The brighter component is located about one galaxy diameter west of the blue galaxy. There's nothing at that location. The blue spiral they call CGCG 376-046 NED01 (I left the NED01 part off of the annotated image). The redshift for the missing galaxy gives a distance of 380 million light-years while the distance for the blue galaxy is listed at 280 million light-years. But then it notes another measurement that puts it about 380 million light-years. So that's what I used for the annotated image as most seem to include it as part of the group anchored by NGC 7146 and 7147. Also, the position of the missing galaxy is given with an error bar of 150" radius or anywhere in a 5 minute diameter circle centered on the position. I'm totally confused by what or where this galaxy is unless it is NGC 7147.

This area of the sky is poorly studied for galaxies. These are the only ones in my image with redshift data. Since there is a short asteroid trail near the top of the image I did prepare an annotated image (see it for details on the asteroid) and gave designations for the few in the image that had designations that weren't just positional. There weren't many of those either.

This was taken on the best of several poor nights I attempted it so doesn't begin to go as deep as I'd wanted to go. In fact, I marked all of them as unprocessable but decided this one night's attempt was worth trying to salvage. I think NGC 7147 may have some faint halo stars well beyond the edge as defined by my image as I see hints of it in the FITS but it was so in the noise I didn't try to pull it out. This shows better when I combined all nights but seeing was so bad for all but this night it may just be an artifact of the seeing. The best seeing frames I left in the image shows a diameter of just over 100,000 light-years using the 380 million light-year distance. NGC 7146 is slightly larger at 110,000 light-years. The blue spiral is 64,000 light-years across if the same distance but if it is really 280 million light-years away then it is only 47,000 light-years in size.

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

Related Designations for NGC7146

NGC7156

NGC 7156 is a face on SAB(rs)cd: spiral in southeastern Pegasus. It is about 72 to 170 million light-years distant. OK, most sources say the distance is unknown. NED, however, puts the redshift distance at more than twice the Tully-Fisher determination. That makes it either 33.5 or 79.1 thousand light-years across. If I had to vote I'd say the redshift distance is likely closer to correct but that's just a guess.

It is a very lonely galaxy. It is considered an isolated galaxy. What attracted me to it was the odd broken arm south of the core. It just suddenly stops then restarts after a 9" gap. Is this really a gap or is a dust cloud blocking that part of the galaxy? I suspect it really has the gap we see. The other reason it was on my list is I'm slowly imaging the Herschel 400 objects I can reach from my 47 north latitude. This one is in the second 400 list. William Herschel discovered it on October 13, 1827. It is in the second H400 program. The NGC describes it as "faint, pretty large, round, brighter middle, mottled but not resolved".

Being isolated there's little on the field. While you will see a couple dozen obvious galaxies none had redshift data at NED. Only two quasars and some 22nd magnitude galaxies had any data. On a good night I could have picked up those 22nd magnitude galaxies but this was a poor night for transparency and the moon was brightening up the sky a bit which didn't help. I took 60 minutes of luminance data rather than my usual 40 but it didn't overcome the bad night and moon. The night really went bad when taking the green data which I saved for last since I can make a reasonable color image without it. One of the two frames was usable though noisy. I made it work.

Due to conditions, only one galaxy was bright enough for me to try and label though you will likely need to blow up the image to find it. It is label GP for galaxy pair which is NED's designation. For morphology they say Merger. So apparently it is two merging galaxies but at nearly 5.5 billion light-years I can't see much but a very faint smudge. The two quasars are also very distant but being quasars were bright enough I could pick them up even though one is nearly 12 billion light-years distant by light-travel time and the other not much closer, at a bit over 11 billion light-years. If not for them I'd not have prepared an annotated image as there wasn't even an asteroid down to 24th magnitude in the field let alone one bright enough to get through my gunky skies.

14" LX200R @ f/10, L=6x10' RB=2x10' G=1x10', STL-11000XM, Paramount ME

Related Designations for NGC7156

NGC7160

NGC 7160 is a rather coarse open cluster in Cepheus about 2570 light-years distant and 19 million years old according to WEBDA. Using a different source Wikipedia says it is 2400 light-years distant. The cluster is one of the objects in the original Herschel 400 list. My description from the list reads: "Open cluster dominated by two bright 'eye' stars and four lesser stars that distract from a scattering of much fainter stars. Scattered and poor but the 'eyes' make it interesting." This from June 14, 1985 using my 10" f/5 at 60x on a humid night. I didn't bother to retype it. The eye stars are B1V (lower) and B1IVe stars so super hot very short-lived massive stars. The lower is still on the main sequence while the brighter has likely already moved off the main sequence so is probably coming to the end of its short lifespan as it has entered the subgiant branch of the HR diagram. t is possible for a main sequence star to be a subgiant. I don't have enough information to say for sure it has left the main sequence due to age. Might be a result of its composition but I doubt it.

When I get a chance I will grab a Herschel 400 object. William Herschel found this one on November 9, 1787. The weather was lousy the night I took this, October 11, 2012. I managed to get only 2 luminance frames that were usable out of 6 taken, 2 of four red and blue frames and one of 8 green frames. I combined all 7 into a pseudo luminance frame. Clouds caused a glare over the cluster due to the bright stars. Color is highly suspect due to the bad conditions. If it were more interesting I'd likely reshoot it but with so many yet to do and it's rather bland nature that isn't likely to happen. I probably should have just left it in mono. The two red frames had little glare but were hit by clouds. It's much nicer in the eyepiece than my camera.

14" LX200R @ f/10, Pseudo L=7x10' RB=2x10' G=1x10', STL-11000XM, Paramount ME

Related Designations for NGC7160

NGC7171

NGC 7171 is in southern Aquarius almost on the border with Capricornus. It is also very near the ecliptic so I expected some asteroids. Thanks to the smoke at -13 degrees only 3 of them are visible in the image. The smoke did help seeing some but dimmed the image by over a magnitude. Note how the three trails I did catch vary due to the smoke and how faint they are. Normally 19th magnitude asteroids are a lot brighter than these.

The smoke also resulted in a rather underexposed image with lots of noise. I needed considerably more exposure time to smooth things out. Still, it came out better than I would have expected due to conditions. This is the next to the last image I took with heavy smoke. Unfortunately, while the smoke is finally history the clouds aren't. It's been mostly cloudy since the smoke cleared. I've only managed two images in decent skies and they were taken the same night.

NGC 7171 was discovered by William Herschel on August 12, 1787, and is in the second H400 program. IC 1417 was discovered by Stephane Javelle on November 4, 1891. It is an Sb spiral by Seligman and Sb? sp Sy2 according to NED. NGC 7171 is SB(rs)b HII by NED and SBb? by Seligman. Seligman seems to like question marks.

Being at -13 degrees and not far from the Zone of Avoidance the field is poorly studied. I wanted to know more about LEDA 942584 but NED had little on it, not even a redshift. It looks interesting with its two well-defined arms. None of the other galaxies in the image but the NGC and IC galaxies have any info at NED. The only other object it has is what it says is a quasar right near IC 1417 by angular separation. The redshift for it is moot as to how it was determined but with only two significant digits for its redshift, I suspect it is photographic and may just be a field star. I included it as there was little else to annotate just note it may not be a quasar. Per NED 7 catalogs list it as a radio source and 5 list it as a quasar. It also has a few entries as an infrared source and an Xray source.

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

Rick


http://www.mantrapskies.com//image-archive/NGC/NGC7171-IC1417/NGC7171L4X10RGB2X10.JPG
http://www.mantrapskies.com/image-archive/NGC/NGC7171-IC1417/NGC7171L4X10RGB2X10CROP125.JPG
http://www.mantrapskies.com/image-archive/NGC/NGC7171-IC1417/NGC7171L4X10RGB2X10ID.JPG

Related Designations for NGC7171

NGC7177

NGC 7177 is an SAB(r)b spiral in western Pegasus. Redshift puts it at 37 million light-years distant but its lack of resolution argues it is much more distant. The median of non-redshift measurements at NED put it at 79 million light-years which seems more reasonable. If the shorter distance is right it is only 32,000 light-years in diameter. That too seems wrong. The larger distance gives a size of 69,000 light-years which also is a better fit so I'm going with it being at least 79 million light-years distant.

The galaxy appears rather face on in some respects but the elongation east-west when the bar runs close to north-south doesn't seem to fit. Either it is oddly distorted or seen more edge on that its inner ring structure would indicate. That is rather odd as it is made up of mainly one bright arm coming from the end of the northern bar. The galaxy is rather red indicating new star formation is rare except for some slightly blue knots at the edge of the galaxy's disk.

NGC 7177 was discovered by William Herschel on October 15, 1784. It made my imaging list because of its odd inner arm structure and its inclusion in the Herschel 400 II observing list. It is another one I have not logged visually though I'm quite sure I've seen it back in the early 80's before I had a field computer to log in such observations for the second H400 project.

I wasn't going to prepare an annotated image as NGC 7177 is the only galaxy in the field with redshift data and there are no asteroids in the image. But then I saw IC 5153 was in the image. That is a very strange object in that it is far too faint to have been discovered by Guillaume Bigourdan with the 12" refractor he had available on September 30, 1891. When he recorded it he said it was "extremely faint, perhaps a star; 9.5 magnitude star 1.4 arcmin to southeast". According to my data, the galaxy is about magnitude 17.3 but the star just below it is magnitude 15.5. At 15.5 the star would just be at the limit of his scope. Thus it seems likely he just saw the star and got lucky that there is a galaxy next to it he couldn't have possibly seen. The 9.5 magnitude star is obvious to the lower left of the galaxy and star below it that he likely did see. NED says IC 5153 "includes the superposed star." Seligman considers it just the star. I put the label on the galaxy. This galaxy is near the top of my image right of NGC 7177.

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

Related Designations for NGC7177

NGC7183

NGC 7183 is a peculiar red galaxy in southwestern Aquarius about 110 million light-years distant. It is well below my normal imaging area where seeing is poor and atmospheric dispersion a major issue. I had to try for it when I had a better than usual night (well what passes for usual this year). The dust lanes are what interested me especially the one coming in diagonally from the lower right side that obviously doesn't follow a spiral pattern. Actually, none of them do. Also, it is very asymmetric with a faint extended region to the southwest. Thanks to faint plume-like extensions I measure its size at about 150,000 light-years. That's one big galaxy. With nothing else in the field at its distance, I'm going to assume its distortion and odd dust is due to a rather significant galaxy it merged with in the not too distant past. I suspect with better resolution a lot of fine dust structure would be seen. It was discovered by William Herschel on September 23, 1786. It didn't make either of the Herschel 400 observing programs.

NED classifies it as S0+ pec. The plus sign indicating it has some characteristics of a Sa or SBa galaxy. That likely refers to the very vivid dust lanes. So vivid I was surprised it was listed as an S0 galaxy. Seligman apparently agrees classifying it as Sa pec? The NGC Project agrees saying Sa: but without the pec label. So much for the "exact" science of galaxy classification. The core of the galaxy is so bright The Sky plots it as a star. Most sources consider the galaxy as disturbed and list it has having 4 companions to the north and 1 to the south. I see 6 to the north and several more to the south. Only two have redshift data. That shows they aren't companions at all as they are some 4 times more distant at nearly a half billion light-years. The northern galaxy has two others, not listed at NED as galaxies in its spiral disk. Are they just background galaxies or members of the same system. Another pair of galaxies without redshift information lie closer to NGC 7183. I assume these two plus the two LEDA galaxies are the 4 others mention as companions. The southern "companion" is likely MRSS 601-107599 which also has no redshift data. Many others without redshift data are in the area and noted in the annotated image, including one seen through the southwest end of the galaxy as a faint blob. Is it a star cloud in the galaxy or really a distant galaxy?

Due to being so low dispersion elongated stars in the luminance frames. The color frames showed much less elongation due to covering a much smaller spectral range. This is why using RGB only is better when this low. But I have only a one hour window this low. It takes me two nights just to do the LRGB if everything goes perfectly. I'd need 4 or more to do it pure RGB so put up with wonky looking stars. Another issue working this low is the image is severely reddened. The only color image I found of it is at Seligman's sight made from the red and blue POSS plates. It shows the galaxy very blue. Even after correcting for the normal loss of blue at this altitude and adding in another 15% for good measure I get a very red galaxy. If I'd add enough blue to match Seligman's image everything would be blue. While no Sloan data for this field exists there is some NOMAD data which I used. Also, there's a quasar at 7.96 billion light-years with spectral data. I used these to try and correct for the blue loss. As mentioned that still didn't seem enough so added an additional 15% "to taste" as Robert Gendler calls it. Sill the galaxy is very red. Since everything else looks reasonable I'm going with this color balance.

The annotated image shows what NED calls a quasar group LQG 11 which they list as having 11 members. One quasar is at the position of the group. Where the other rest are I have no idea. There are 4 galaxies in the image with a redshift that puts them 480 million light-years away and three others at 1.71 billion light-years. These appear to be two related groups.

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

Related Designations for NGC7183

NGC7184

NGC 7184 is a great spiral galaxy in southern Aquarius that is listed as a barred ring galaxy with a Low Luminosity Active Galactic Nucleus about 110 million light-years from us. It is also a huge spiral. I measure it at 200,000 light-years across.

It was discovered by William Herschel on October 28, 1783 and is in the second Herschel 400 observing program. The other major galaxy in the image is NGC 7180. It too is an LLAGN galaxy but is classified as S0 and is much closer at about 43 million light-years by redshift and 60 by non-redshift measurements. Its size is 20,000 to 30,000 light-years across depending on which distance you use. It too was discovered by William Herschel but on September 11, 1787, nearly three years after he found NGC 7184. There's some disagreement here however with some saying William never saw it and giving credit to his son John for finding it September 23, 1830. It's not in either of the H400 programs.

They are also the most southern galaxies I've been able to image with some clarity at almost -21 degrees. My usual cutoff is -15 degrees and that suffers quite a bit most nights. My skies this low are limited due to the wall of my observatory and trees I can't prune in any way even though I own them as they are in the shore impact zone. Also, my seeing this low is usually awful as fog rising from the lake greatly limits transparency and sucks all blue light from any but the brightest objects.

I lucked out in that this was a night of the best seeing this low I've had in the 12 years I've been observing here. Also, transparency wasn't as bad as usual but it still sucked out much of the blue light of dimmer objects. So much so fainter objects had no blue at all. If I could have had more time for color data it would have helped but I get only 100 minutes between trees without it being too low. My Meridian Tree prevents imaging an hour and a half either side of the meridian forcing low objects to be even lower.

While I had a heck of a time with color balance as blue was lost totally in fainter things, unusually weak in medium bright objects and only slightly bothered in bright objects. This meant I had to scale the color adjustment to take this into account. Even eXcalibrator had issues I've never seen before. So while I've said before "the color is suspect" I really mean it this time. I found only a few color images of either NGC galaxy in the image and none came close the same color balance. Especially for NGC 7180. All showed it either blue, yellow-white or somewhat orange. None showed the golden core and blue outer regions I ended up with but since color correction was applied by magnitude that may have had severe consequences. Those with -20 degrees objects high overhead instead of along the horizon as it is here may get reasonable results.

For all the color issues I was surprised it went as deep as it did. To the southwest of NGC 7180 is a galaxy that's 4.7 billion light-years distant and magnitude 21.9. Some nights reaching that high overhead is a challenge in 40 minutes of luminance data let alone only about 15 degrees over the lake thanks to my being unable to catch it near the meridian.

Why nearly all the galaxies NED had redshift data on were west of NGC 7184 I can't explain. I see as many to the east. Some survey may have ended at its right ascension I suppose. It is in the Zone of Avoidance so the Sloan Survey hasn't taken this part of the sky.

One asteroid is obvious near the right edge of the frame. Several others are in the frame but too faint for conditions. I can't even see them on the FITS stack.

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

Related Designations for NGC7184

NGC7193

NGC 7193 is considered by some to be an asterism, others such as SIMBAD say it is an open cluster. But the only paper on it that I found says it is an OCR. That doesn't stand for Optical Character Recognition as my brain first thought. In this case, it stands for Open Cluster Remnant. After lots of deep reading the paper says; "We conclude that NGC 7193 is a 2.5 Gyr OCR composed by 15 confirmed members and 19 probable members and located at about 500 pc away from the Sun." It can be found at https://arxiv.org/abs/1610.00972

The age likely explains the lack of blue stars though it appears still somewhat too red. Located under the neck of Pegasus I'd not expect it to be dust reddened. I found only one color image of it and that agrees to my color. The group was discovered by John Herschel on October 2, 1825.

There's one galaxy in the image, IC 5160, an SB0 galaxy at just under 400 million light-years. It was discovered by Stephane Javelle on October 15, 1903. It too seems rather red so maybe there is some dust reddening this field. Though it may just be a red and dead galaxy.

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

Related Designations for NGC7193

NGC7209

NGC 7209 is a type III1p open cluster in Lacerta discovered by William Herschel on October 19, 1788. It lies about 3800 light-years from us and is a bit over 400 million years old per WEBDA. It has two rather red stars near its center. Some amateur images call these carbon stars though I can't find anything to support this. My sources say the brighter is a K4 star while the fainter is a late G star. How late varies a bit. Neither are listed as being carbon stars. The Sky's database puts the K4 star at 5700 light years, SIMBAD says nearly 15,0000. Either way, it isn't likely a member. I can't find a distance for the G star in The Sky, Simbad puts it at 2100 light-years. I don't have error bars for either the cluster or star. I suppose it possible it is in the cluster as these distance determinations are usually pretty fuzzy. But it isn't a carbon star that I can find.

This cluster is in the original Herschel 400 list and thus was on my to-do list. When I went to process it I found all frames had a nasty reflection that at first fooled me into thinking it a nebulous patch near the cluster as it had interesting somewhat linear dark bands that were rather sharp-edged. Unlike most reflections that are rather fuzzy in detail. Still, I was unable to coax it out of any published image, some obviously quite deep. I found it nearly impossible to remove from the luminance data. It was far fainter in the color data, strongest in blue and nearly absent from the red. Even in the blue, it was faint enough I easily removed it. Thus, without a useable luminance, I just processed the 6 RGB images. That meant it doesn't go as deep as I normally do but considering the vast number of background stars cluttering the luminance frame that is actually a good thing. For so limited data it came out quite well. Though I'm not sure why my system decided to take this low priority object on what appears to have been a better than average night. Though from my latitude it was nearly at the zenith so in my best seeing part of the sky when this was taken.

My visual notes from June 14, 1985 agree with the image. They were made under very humid conditions with fair to poor transparency and read: "Large, bright, even but coarse cluster almost lost against a rich Milky Way background. This cluster stands out much better when I stopped the telescope down to 6". It will be lost in anything much larger than my 10" scope." Even limited to RGB data it is pretty well lost in this image with a 14".

14" LX200R @ f/10, L=none RGB=2x10', STL-11000XM, Paramount ME

Related Designations for NGC7209

NGC7212

NGC 7212 is a train wreck of galaxies under the neck of Pegasus. It consists of three galaxies which most sources say are interacting. I'll agree two certainly are but the third may be but it is little distorted and has no redshift value I could find so I can't place it in the vicinity of the other two. The only thing going for it that I can see is it has an odd dust lane south of its core that appears to cut the southern part of the galaxy off as if a galactic chainsaw hit cut it off. The two galaxies with known redshift are about 350 million light-years from us.

The two obviously interacting galaxies have a mash-up of tidal plumes. They are both heavily distorted by the interaction. The northern small galaxy has a dust lane at an angle to its plane. NED doesn't try to classify any of the galaxies but does show the main one as a Seyfert 2 galaxy. The NGC Project lists the main one as Sb while Seligman says Sb?. I find it odd no one gives it the pec label. The galaxy was discovered by Lewis Swift on October 2, 1886.

To the south of NGC 7212 is what appears to be a pair of galaxies. They may just be in the same line of sight or interacting. It's hard to tell. NED just identifies the pair with one entry as an UltraViolet Source with no further information.

Near the bottom of the image right of center is a short asteroid trail left by (84094) 2002 QB47 at magnitude 17.4. With nothing else with any useful information, I didn't prepare an annotated image.

A raw HST image of this train wreck can be found at https://commons.wikimedia.org/wiki/File:NGC_7212_hst_05479_606.png

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

Related Designations for NGC7212