NGC6829

NGC 6829 and NGC 6831 are a pair of possible interacting galaxies in Draco. Though the lower left corner of the image lies in Cygnus. NGC 6829 is listed as an Sb galaxy by NED and the NGC Project. Seligman says Sb?. Redshift puts it at 144 million light-years. The CGPG says of it: "Red 'sandwich' galaxy, heavy absorption line, twisted tips, internal compact knots." To me the entire southern part of the galaxy is weirdly distorted showing two dust lanes rather than just the "sandwich" lane. It is surrounded by a large halo that extends further to the southwest than the northeast. I measure its size at 95,000 light-years.

NGC 6831 is a truly strange beast. It is classified by NED and the NGC Project as S0 while Seligman says S0?. What very few images of it I find show only the core which indeed looks to be an S0 galaxy but my exposure picked up an outer region that paints quite a different picture. It has an odd blue loop that as it comes across the galaxy it appears to change into a red dust band. But a closer look shows these to be two separate features with one ending near where the other starts. Still, such features are normally seen in S0 galaxies. Are they evidence of a polar ring? Are these features due to interaction with NGC 6829? I found nothing on either of these galaxies. NED's redshift puts it 151 million light-years distant which makes it 83,000 light-years across its long axis. Though if this is a true oval galaxy with an unknown orientation its true size may be larger.

Both of these galaxies were discovered by Lewis Swift on September 3, 1886.

Actually, these are two of a trio of galaxies. I was so taken with how odd NC 6831 was I totally missed this. The third galaxy is UGC 11475. It is out of the field to the south though its very northern outskirts show as a blue glow on the very bottom edge of my image a bit right of NGC 6829. It is listed as SBd at NED with a redshift placing it at a distance of 142 million light-years. The trio is known as UZC-CG 268. If my brain had been in gear I could have included it in the image. I don't know how I missed this.

This field is within the Zone of Avoidance which is little studied for galaxies. As a result, these are the only ones with redshift data. With so little to annotate, I didn't prepare one. This is my first image finished in October. I'm only 3.5 months behind and with December and so far January a dud that's more like 2 months behind. I may get caught up if this horrid weather continues.

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

Related Designations for NGC6829

NGC6830

NGC 6830 is an open cluster in Vulpecula. When time and skies permit and nothing else is in an optimum position I work on Herschel 400 objects. This is one of them. It was discovered by William Herschel in 1784 using his 18.7" reflector. My notes from my Herschel 400 log dated May 20, 1985 reads "An open cluster at the north end of a rich star cloud extending north from 12 Vulpecula. Hard to tell where the cluster ends and the star cloud begins! The cluster is good the field is even better!" I was into exclamation points at the time it seems.

WEBDA say the cluster is reddened by a half magnitude, it is 5,300 light-years distant and about 37 million years old.

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

Related Designations for NGC6830

NGC6834

NGC 6834 is an open cluster in Vulpecula that fits my limited field of view. I took it more of a test of a new method I thought up of better pulling a cluster from the background Milky Way stars. I've had problems with them getting lost in the Milky Way's starry background. I developed some different curves that bring out the brighter stars but holds back background stars somewhat. I tried this with two approaches. One using a luminance stack to pick up any background galaxies and the other using only RGB data. Due to the loss in the filters and not exposing long enough to be sky limited the fainter stars are greatly reduced but the brighter ones come though well. Sort of like using less aperture. RGB always helps star colors as well. For this purpose, I prefer the RGB version but am presenting both in case you disagree. Let me know which you prefer.

Details on star clusters are often sketchy. Dreyer's description reads; Cl,P,lC, st 11...12 which translates into cluster, poor, little condensed with 11th and 12th magnitude stars. Dreyer would be rather impressed I'd think by what today's small telescopes see when looking at his "poor cluster". WEBDA says this cluster is 76 million years old and is 6,700 light-years distant while Wikipedia says it is 65 million years old ± 18 million years and is 7,000 light-years distant. Quite reasonable agreement for a change. SEDS puts its diameter at 5 minutes. At a distance of 6,850 light-years (splitting the difference), it would be 10 light-years across. I found little else on the group. It was discovered by William Herschel on July 17, 1784. It isn't in either H400 program.

I started this one night but only got 2 blue images before clouds nailed me. I then retook it assuming the blue frames were cloud damaged but they were fine so I used them along with the normal data and incorporated them into the pseudo luminance image used for that version.

14" LX200R @ f/10, L=4x10' or pseudo L=8x10' RG=2x10' B=4x10'

Related Designations for NGC6834

NGC6835

NGC 6836 is a rather odd spiral galaxy in northeastern Sagittarius. It's a rather featureless low surface brightness galaxy with a few scattered blue star clusters. Any hint of arms in the featureless disk is so faint I can't really see any. The RC1 (Reference Catalogue of Bright Galaxies -- 1964) Describes it: "Bright middle, no bright nucleus. Very faint spiral arms or arcs. Very poorly resolved. Low surface brightness. Non-interacting pair with NGC 6835 at 7.5 arcmin." I find the "...no bright nucleus" part hard to understand as my image shows a tiny but bright nucleus. It is classified as SABm with a redshift distance of 65 million light-years. At that distance, it would be about 29,000 light-years in diameter so a near dwarf. Unfortunately, that's about all I was able to find on it. Thanks to the odd gap in its disk filled by three bright field stars in our galaxy it looks like a glutinous Pac-Man that is eating three pellets at a time.

It's companion to the northwest is NGC 6835. It appears to be an edge on spiral. The 1994 Carnegie Atlas of Galaxies Vol. 1 says of it: "The classification of NGC 6835 is uncertain. From the asymmetry in the pattern seen in the short-exposure image at the top right, one guesses the presence of spiral structure ... No resolution into components of the stellar content is seen ... the Amorphous? classification is suggested." NED classifies it as SB(s)a? with some spectral lines. Its redshift is similar to that of NGC 6836 putting it 64 million light-years from us. This indicates they are likely true companions. It's much larger angular size gives it a diameter of 45,000 light-years, rather typical of many spirals.

Both NGC galaxies were discovered by Édouard Stephan on the night of August 2, 1881.

Sloan indicates about 0.54 magnitude loss in green light and 0.4 magnitudes in red. Another source puts blue's loss at 0.62 magnitudes. I applied these adjustments to the two galaxies. Stars and other galaxies were adjusted to G2V standards. Usually, I don't adjust galaxies separately but without this NGC 6836 was mostly white and NGC 6835 too red. They looked more "natural" with the adjustment.

NED had redshift data for only one other galaxy in the image. It is shown on the annotated image. I'd ordinarily not prepare one for a field with so little in it but two of the three asteroids wouldn't be found without one.

Conditions for this one, as usual, were very poor. The third frame of 4 was mostly lost to conditions as shown by the gap in the asteroid trail. Seeing deteriorated and was really bad for the red frame. This results in some red halos around brighter stars as their size was nearly double the blue stars. It didn't help that this field is at my southern limit for even a very good night. But considering how poor conditions have been all year I've have little to do if I waited for good conditions.

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

Related Designations for NGC6835

NGC6840

I've been taking clusters that get no respect from imagers. In this case, the disrespect seems deserved. I'm wondering why I even put these on that list as there's nothing much here. Probably because it gave me the chance to catch two "nothings" in one narrow field of view. Unfortunately, I apparently forgot that twice nothing is still nothing.

This field is in northeastern Aquila. It has two NGC objects not in the RNGC catalog (R for revised). Though most NGC listings include them. This is because most feel they are both just asterisms the Herschels recorded as clusters. William Herschel recorded the stars of NGC 6840 on September 4, 1784 and John recorded NGC 6843 on July 29, 1829. NGC 6840 is in neither Herschel 400 observing program.

While a bit east of the main part of the Milky Way there still is a lot of dust in the region. I doubt enough to turn blue cluster stars as red as most of the stars seen here, however. Unfortunately, being considered asterisms I found virtually nothing on either of these. WEBDA lists neither. My The Sky 6 calls both a "Double Star" and gets the position of both wrong for clusters but maybe right for double stars The annotated image shows both the "correct" position for these asterisms as shown in most catalogs as well as the double stars The Sky 6's database points to. The one for NGC 6840 is very obscure. Why they picked that I have no idea.

Since I was using NGC 6840 as my centered object I almost fell for this until I noticed the true asterism and changed my center point. Good thing I was at the controls that night. The annotated image shows the only three galaxies NED lists in the image though several more can be seen. Due to the size of these files I've reduced them to 1.5" per pixel rather than my usual 1" per pixel.

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

Related Designations for NGC6840

NGC6842

NGC 6842 is a planetary nebula in Vulpecula. It was discovered by Albert Marth on June 28, 1863. Determining the distance to planetary nebulae is difficult. Most posts of this one don't list a distance. I found several ranging from 4400 to 8800 light-years. The later one has an error bar of 3000 light-years. In other words, the distance is still pretty vague. Most papers on this one were behind paywalls so I was unable to learn much.

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

Related Designations for NGC6842

NGC6846

NGC 6846 is located in southern Cygnus about 14,500 light-years distant. It is a rather small cluster, likely due to its distance. The NGC Project gives a size of only 30" of arc for the cluster. I get a size more like 45 seconds if the bright stars are used. Otherwise, the edge is impossible for me to discern. It is classified Trumpler class IV1p which really stumps me. IV indicates a cluster that doesn't stand out from the background. That would rule out the bright stars I used as members. The "1" means its stars are of very even brightness. So now it is either the bright or dim ones and since the bright ones are ruled out that leaves the dim ones. Since they do fade into the background with no edge I can see how was its size determined? The "p" means it has few stars (less than 50). I suppose this means it isn't the obvious stars but the faint ones that make up the cluster. Using a 17.5" scope Steve Gottlieb says of it: "...at 225x appears as a small, faint clump of stars over unresolved haze." The cluster was discovered by Édouard Stephan on August 17,1873 but he had use of a 31" reflector. For some reason, while Stephan got the position right the RNGC and a few other sources put it 2 degrees south of the right position. Fortunately, The Sky has it correct or I'd have taken only stars.

Using my larger size of 45" and a distance of 14,500 light-years, the cluster is only 3.2 light-years across. WEBDA gives it an age of 400 million years and says it is reddened by a full magnitude.

The Sky told me there was a planetary nebula just northeast of the cluster. In fact, it said there were two. SAC 68+1.1 and PLN 68+1.1. They are plotted 35" apart even though it is obvious they are the same Planetary. Turns out when I plate solved for them neither position was correct. Fortunately, NED has the position that matched a blue nearly star-like object in my image except its PSF was all wrong for a star but reasonable for a planetary nebula of that size. I've noted it in the cropped image.

The full image does contain one galaxy that got through the dust of our galaxy. The field is only about 1 degree from the galactic plane so very heavily obscured. It is in the lower left corner and except for its PSF indistinguishable from a star. It has no info, not even a magnitude, just a position so I didn't point it out.

Since my usual exposure times are overkill and because two of the 4 luminance frames were full of satellites, I used only the two free of the many trails. I only took one frame of each color. Somehow all those satellites failed to show making it unnecessary to clone any trails out. On a night of good transparency (though not good seeing this night) I can get away with only one color frame when no satellites show up.

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

Related Designations for NGC6846

NGC6852

NGC 6852 is a blue planetary nebula in east-central Aquila. I found distance estimates ranging from 5,100 light-years to 13,800 light-years. The most recent I found said 7,400 light-years and gave reasons why the others were wrong. http://adsabs.harvard.edu/abs/2004MNRAS.353..589P

I was surprised at how many distant galaxies were in the image being the field is on the east edge of the Milky Way and thus quite heavily obscured. Or so I thought. Seeing all these faint fuzzies makes me think it isn't nearly as obscured as I suspected. However, none of these are in the NGC, IC or PGC catalogs that I could find. NED showed no redshift data for anything in the field.

What few images of this one I found on the net all show the central star very easily. Half show a second star that's somewhat red to the northeast. Half don't show it. In some images it is nearly as bright as the central star, for most, it is fainter but still obvious. Yet in the other half, there's no sign of it. In some cases, the resolution is too low but others with sufficient resolution don't show it. I see a hint of it in the original FITS file. My resolution was poor this night but it should at least have shown as an elongation to the NE but doesn't. Could it be a variable star with a deep long minimum? Or is it just too red for my camera's weak red response? The nebula was found by Albert Marth on June 25, 1863.

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

Related Designations for NGC6852

NGC6856

NGC 6856 is a star group located in Northern Cygnus. It was discovered by John Herschel on September 24, 1829. I can't tell you how distant it is. There is no agreement over whether this is a star cluster or an asterism. While it is listed in the NGC, the Revised NGC lists it as non-existent. SIMBAD doesn't list it under an NGC number. WEBDA has no listing for it at all. In my image, the range of star colors seems about the same as the rest of the field. I found no Hipparcos data for any of its stars. Thus I'm coming down on the side of it being an asterism. It might not be as cute as the "Coathanger" but certainly is obvious.

While there are a few galaxies in the image, none have redshift data at NED. In order to push the star colors in a cluster of lightly colored stars, I reduced the luminance level causing the galaxies to be less obvious. Since I had no data on them, not even a magnitude, just a positional catalog name (a couple are in the PGC as well) I didn't prepare an annotated image.

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

Related Designations for NGC6856

NGC6866

NGC 6866 is a beautiful open cluster in Cygnus that doesn't get the attention it deserves. Not only is it a great open cluster of very blue stars they contrast with the background red glow of the H alpha emission that floods much of Cygnus. It is located about halfway between Sadr and Delta Cygni which marks the end of its western wing. It is included in the first Herschel 400 observing program though there's some question whether it was discovered by him or his sister Karoline Lucretia Herschel. Sources seem divided on this issue. Those like the NGC Project crediting William say it was found in 1790 while those such as Seligman say Karoline found it 7 years earlier on July 23, 1783. Neither side seems to address this controversy. Since it is the earlier date I'll go with Karoline as the discoverer.

My comments on it from May 19, 1985 using my 10" f/5 at 65X under good conditions (for a change) reads "Small, rich, open cluster whose brightest stars are arranged in two parallel arcs." Even using an H beta filter I doubt I'd have seen the faint nebulosity that fills the area so I'm not surprised that wasn't mentioned. The two arcs I mention are rather obvious in my image being concave to the south. Usually, after processing my digital images of star clusters, they look nothing like my visual description. This one is a rare exception.

WEBDA says the cluster is 4700 light-years distant and some 375 million years old. Though a new paper dated July 21, 2015 puts the distance at 3,875 light-years +/- 250 light-years with an older age of 813 million years give or take 50 million years. The paper is at http://arxiv.org/pdf/1507.05968v1.pdf This paper from 2014 using Kepler data (The cluster is was in Kepler's field) http://arxiv.org/abs/1403.7208 puts the distance as 4,000 light years and the age as 705 +/- 170 million years. These two papers are in rather good agreement for this sort of thing. I am bothered by the lack of red giant stars. By this time I'd expect a few to have developed.

This was taken the one good night I had in July. But it was an unusually hot night and I could cool only to -15C thanks to it being a 30C night. Most summer nights are no warmer than 18C so I can cool to -25C. At that temperature dark current is low enough it has no impact on the image. But at -15C it does to a measurable extent. Then moon rise left me with time for only one 10 minute frame for each color before it was so bright it was skewing my color data. I planned on getting more but the weather never cooperated so went with what I had. Not realizing it was in nebulosity I find that sufficient for bright objects. I was surprised when it was sufficient at the warm temperature to still show the nebulosity in the field with good color. Of course, it may have been even better with more color data. But this turned out so much better than I expected I doubt I'll go back for a reshoot.

This one ends July on an up note as most of the month was horrid due to weather and fires in the northwest sending me so much smoke I might as well have been in Manhatten for the number of stars I could see naked eye many nights. I only managed 8 images all month, most poor. Several others were started in July but reshot under better conditions in August.

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

Related Designations for NGC6866