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FGC 1735/NGC 5529 Impressive galaxy and field

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#1 Rick J

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Posted 05 February 2013 - 04:18 PM

Why such an impressive galaxy and field is so rarely imaged I can't fathom. Looking back through this forum for 5 years turned up no images of this fantastic galaxy. Why?

NGC 5529/FGC 1735 is a massive flat galaxy with a warped disk in Bootes about 140 million light-years from us. At that distance it is a bit over 250,000 light-years across, twice the size of our galaxy which is a big one. Thus it met two criteria I use for finding targets, a member of the FGC catalog and distorted. It should remind you of the Needle Galaxy NGC 4565 and NGC 128 though there are some major differences. NGC 4565 has a round central bulge while NGC 5529 has a box like core with 4 "points" much like NGC 128 I ran October 1st of this year. Also like NGC 128 both arms are warped in the same direction while with NGC 4565 the arms are warped in opposite directions and only at the very ends. It does have the strong dust lane and coloring of NGC 4565 while NGC 128 had neither but did have the most obvious box or peanut core I know of while it is rather subtle in NGC 5529. The "points are rather hidden on the northern side unless you look for them. NED and the NGC project class it as an edge on Sc galaxy. One paper says it is exactly edge on though to me it appears a few degrees away from that as the dust lane is a bit north of being centered and the northern "points" of the box are mostly hidden behind the closer structure of the galaxy while the southern points are seen against black background sky.

A box structure is usually indicative of interaction with other galaxies, usually from digesting a companion or two. NGC 5529 certainly has some dwarf companions but none appear large enough to warp a galaxy of the massive size of NGC 5529. So I'm going out on a limb and say the warping is due to galaxies it digested long ago creating the box-like core. In the annotated image I've noted the true companions by showing their catalog name as well as a redshift distance in the 140 to 150 million light-year range. The differences are due to orbital motions about the group rather than actual distance differences. Note three of the 4 companions are very small, IKPM 1, IKPM 2 and Kregal B with MCG +06-31-085a being larger but very diffuse and low density. There are other galaxies "near" NGC 5529 but they are much more distant and thus not true companions. I found several images of this galaxy claiming KUG 1413+364 was a companion. Sure appears likely but the redshift shows it to be more than twice as distant. Appearances can be very deceiving. Note "nearby" galaxies over a billion light-years away are larger in apparent size than some of its true companions. The star-like feature in MCG +06-31-085a is composed of two blue knots of stars in the galaxy that nearly overlap. My resolution is not sufficient to separate them. In any case its not due to a foreground star as it might appear.

There's a good paper on this galaxy at: http://www.aanda.org...standard&Ite... As published: http://www.aanda.org...1/aa7729-07.pdf .

To the east of NGC 5529 is a small galaxy group at a distance of about 890 million light-years. One member of the group is highly distorted, MAPS-NGP O_271_0108262. I've included it as an inset in the cropped and enlarged image. The apparently closest galaxy to the south has no redshift. While appearances can be deceiving I'm going to assume it is likely the cause of the tidally distorted arms on the galaxy to its north.

I often come across galaxies missed by NED. I happened across many in this image. One is right below NGC 5529. I've marked them in the annotated image with question mark. In the upper left you'll find three question marks in a row. This is because the three galaxies to their left are all missed by NED. Though two, left most) appear to be one in my image the Sloan image shows them both quite clearly. Most interesting is the example to the southwest where I marked SDSS J141632.42+360550.5 which is a tiny faint galaxy almost lost in the glare of a far larger and bright galaxy to its south. The big one is not in NED for some reason. That's often the case, faint ones picked up, brighter are overlooked. Why I don't know. I made no search for these. I have only noted those I happened across while annotating the image. How many more there are in the image I can't say. NED picks these up using automated software. It seems there's still some bugs to be worked out in the detection algorithms.

Edit: I forgot to mention this is my first April 2012 image. I'm slowly working through the backlog.

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

Full frame at 1" per pixel


Attached image at 0.8" per pixel


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#2 dickbill


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Posted 05 February 2013 - 04:43 PM

Very nice color rendering and of course resolution, as always.

Do you do LLRGB, RRGB or something different in photoshop ?

#3 Rick J

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Posted 05 February 2013 - 05:56 PM

I process the L image for detail then create the RGB image using usually G2V calibration but if sky conditions are poor and good data is available at NED I'll use eXcalibrator. Then neutralize the background. After that I use mostly Lab mode tools to bring out the color, rarely the RGB saturation control, if so never very strong, certainly not over 30% as it can do some nasty things when pushed very far often requiring heavy blurring to remove. Once I have the color where I want it I'll combine it with the L image usually with color on top rather than the L channel on top as most do it. Rather than adjust the L level down to match the color I use curves to bring up the color layer. Both layers are initially well below the 255 max of the histogram to preserve star color. Only after everything else is done will I adjust the contrast (S curves not contrast control) and levels to use the full histogram and give the image some pop without maxing out the histogram at the top.

Many small steps rather than a few large ones is an important concept to learn, at least for me.

There is no one way to do this, Pix Insight offers entirely different tools. Not having a reasonable internet connection I've not watched the on line tutorials, they take hours to load on the poor connection we have here in the boonies. A fast service did come into the area but stopped at my township line. We only have 36 residents (38 counting babies-twins) and half leave for winter in a 36 square mile area. Guess they didn't think the cost of the cable could be recovered with so few to use all those miles of cable. Those who have mastered Pix Insight seem to think it superior. I can't comment either way.


#4 PrestonE


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Posted 05 February 2013 - 06:03 PM

Very interesting field Rick. And
as usual a very nice write up.

Always a pleasure reading your post.

Best Regards,


#5 dickbill


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Posted 05 February 2013 - 06:22 PM

I don't have pix insight either. I use Envisage from Meade and then Photoshop. With my earliest pictures at short focal and short poses, I had trouble preserving saturated colors in LRGB, a common problem apparently, which can be resolved with the LLRGB technique, from Rob Gendler at http://www.robgendle....com/LLRGB.html

But now working at longer focal lenght and longer exposures in narrowbands, the colors i obtain are quite saturated, and that the final result can vary greatly with small variations. I am afraid that I have to use a G2V star to calibrate the color too.
Thanks for the info. Whatever is your technique, it works well.

#6 David Pavlich

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Posted 05 February 2013 - 06:43 PM

Neat picture, Rick!!


#7 Mike Wiles

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Posted 05 February 2013 - 07:01 PM

Why such an impressive galaxy and field is so rarely imaged I can't fathom. Looking back through this forum for 5 years turned up no images of this fantastic galaxy. Why?

After this image, I'm left asking the same question. What a fantastic galaxy!!


#8 mcarroll



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Posted 05 February 2013 - 09:17 PM

Nice image Rick, some interesting galaxies here.

#9 IcecreamLtDan


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Posted 05 February 2013 - 10:08 PM

Rick, I find your posts and pictures to be among the most fascinating I encounter on this forum. Thanks for the pictures and the descriptions you so obviously spend painstaking amounts of time on.

#10 Rick J

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Posted 06 February 2013 - 02:50 PM

Thanks all.

This is a fun galaxy few seem to know about for some reason. Maybe most are too busy taking the nth image of the same objects they took previous years.

Weak color is usually due to the color layer being dim compared to the Luminance layer. Often the case when imaging faint nebula, common to what is often done with a wide field fast scope. Think your issue was more to do with choice of targets than the f ratio. While LLRGB can help I get far better results with my system so no longer use LLRGB.

There are almost as many ways of processing an image as there are imagers. Each has to find what works best for them and their images.


#11 neutronman


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Posted 06 February 2013 - 11:13 PM

Yeah, very cool field indeed!

#12 J.P.M



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Posted 07 February 2013 - 06:47 AM

Cool, many thanks!

#13 broca


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Posted 07 February 2013 - 07:01 AM

Well done Rick!

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