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Who has observed NGC 4236, Draco?

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#1 Philler

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Posted 26 March 2014 - 10:27 PM

Herein lies the problem of visual magnitude listings in catalogs and atlases: You will be left with the impression that a DSO would be a nice, easily seen object, listed at 8 or 9th mag., 10 or 15 arc minutes in size. But what sometimes happens is it turns into the invisible man even under great skies and seeing conditions.
I have tried several times with my 10 in. from a dark blue zone to see 4236, and nothing. I looked at a photo on Wiki of 4236 to see if it actually existed and even the photo was a pathetic image of it.
I am sure there are a number here who have seen it, especially with larger scopes.
Some of the older sources and catalogs don't bother giving surface brightness or how faint or bright something shows especially on galaxies.
So if you just can't find 4236, never fear, you are not doing anything wrong, you are chasing a ghost. The area where it is supposed to be is easy to locate about 10 deg. north of the UMa bowl. So, if you like a real challenge, go for it. Personally, I gave up.

Just a note: 4236 is part of the M81/M82 group which may partly explain why it suffers from very low surface brightness problems. This is similar to the nearby effect with galaxies like Leo I. Photos really show its very diffuse appearance. But if it has a SN sometime in the future it should get lots of attention.

#2 David Knisely

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Posted 26 March 2014 - 11:48 PM

Don't give up! NGC 4236 is a very large (22' arc x 7' arc) highly tilted barred spiral galaxy. Despite its commonly-listed total visual magnitude of 9.6, it has a very very low surface brightness (around 15 mag. per square arc minute), so it can be harder than it might seem when looking at just the numbers. It is indeed quite hard to see at times, although an 8 inch should show it under very dark skies and moderate magnification (I have seen it in a 9.25 inch SCT on a really good night). I failed initially from my modestly dark backyard in my 8 inch, but once I got my 10 inch, I finally caught its very dim diffuse cigar-shaped glow. From my dark sky site, it was notably easier although still fairly faint. It may be best shown at between 50x and 100x in that scope. Indeed, I could just barely make out hints of the interior bar with my 10 inch, although the detail was notably easier to see in my 14 inch Newtonian. Clear skies to you.

#3 Bill Weir

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Posted 27 March 2014 - 12:28 AM

Definitely keep trying. I just looked this up in my Herschel 2500 log. The only observation I have of it is with my 6" dob.

05/22/08 6" dob; Galaxy, large, very faint, ? face on?, slightly brighter elongated core.

This pretty much matches what I see in the DSS image and as part of my program I don't look up images before hand of what I'm searching for. I don't want my impression skewed by what I'm supposed to see. All I go on is coordinates of where I should notice something and the type of object and maybe the size.

Even with my 20" I can be constantly amazed at how difficult an object can be when by magnitude it could be assumed to be easy and visa versa. Hang in there.

Bill

#4 sgottlieb

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Posted 27 March 2014 - 01:25 AM

With a huge, but very low surface brightness galaxy like this, it's important to use low power (under 100x in a 10") and look for a ghostly streak. Unfortunately, it doesn't have much of a core, so there's not a brighter center to stand out.

In a larger scope, some of the knotty HII regions are visible so this is a nice target. These are notes with my 18"...

18" (4/26/08): this huge, low surface brightness galaxy extends roughly 12'x3', oriented NNW-SSE. There is only a very weak central brightening with no obvious core. A very faint star appears to be superimposed near the geometric center and just to the south is a slightly elongated brightening (possibly the core).

Another brighter region is near the north end of the galaxy. This patch seems elongated at 45° to the major axis, appearing to extend out to the west of the main glow on the north end. Images reveal this is a gigantic HII complex and is catalogued in the Hodge-Kennicutt Atlas of HII regions (1983AJ, 88, 296) as NGC 4236:[HK83] 15, 16 and 17.

The south end is also splotchy and at the very south tip are two very faint "stars" that seemed slightly fuzzy. These are also two small HII knots, listed as NGC 4236:[HK83] 02 and 03. One or both of the knots also carry the designation VII Zw 446, described by Zwicky as a "blue patchy compact [galaxy]".

#5 Carol L

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Posted 27 March 2014 - 12:25 PM

I didn't need large aperture to detect this galaxy, but low magnification and a wide fov seemed to help quite a bit. Attached is a sketch from a few years ago, done while using a 120ST. (The galaxy was a bit fainter in the eyepiece, though - I use an extremely dim red light and need to keep layering the graphite until I can see it on the paper.)

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#6 IVM

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Posted 27 March 2014 - 01:02 PM

I need to reobserve this galaxy more carefully. So far I have only made a brief observation and a crudely drawn schematic (it is embarrassing to post it next to Carol's sketch). This was done with 12" from a blue-zone site. The asymmetry that I noticed in the core is related to the innermost dark lane along the near side of the bar.

"Core 1/3, halo 1/2 of the distance between flanking stars. Core sharper away from the bright star."

N is left and W is up, approximately (SCT with a diagonal)
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#7 Astrojensen

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Posted 27 March 2014 - 04:04 PM

I've observed this galaxy a few times in small telescopes. The very first scope I saw it in was an old 4.5" f/8 newtonian, using approximately 50x. I've since seen it a few times in my 63mm Zeiss Telemator, but only VERY dimly and only under the best possible conditions (SQM 21.7 or better and VERY clear skies). I suspect it *should* be visible in 10x50 binoculars to a super experienced observer under the most amazing conditions, but I've not heard of any binocular sightings.


Clear skies!
Thomas, Denmark

#8 hbanich

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Posted 27 March 2014 - 06:48 PM

I have an observation of 4236 with my 28 inch:

"NGC 4236 is (a) surprisingly big, faint and elongated galaxy with a companion galaxy on one end (star-like PGC 39369 at mag 15.8). 263x, SQM 21.56."

I had thought the faint "wing" on the opposite end of 4236 was PGC 39369 at first, but checking Megastar showed my mistake. Also, a couple of the faint stars nearby might be some of the HII regions that Steve mentioned.

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#9 jack45

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Posted 27 March 2014 - 08:49 PM

Carol L

Excellent job, Carol just the way I saw it.

Clear Skies!

#10 Mike Harvey

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Posted 28 March 2014 - 12:15 AM

With a 28" and Mallincam, this galaxy looks almost exactly like the (excellent) image that is posted earlier in the thread.

VISUALLY, in the same scope, it reminds me of M-108 in Ursa Major.
Dimmer, yes, but lots of mottling and several very obvious bright 'clumps'.

#11 Philler

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Posted 28 March 2014 - 12:59 AM

Definitely keep trying. I just looked this up in my Herschel 2500 log. The only observation I have of it is with my 6" dob.

05/22/08 6" dob; Galaxy, large, very faint, ? face on?, slightly brighter elongated core.

This pretty much matches what I see in the DSS image and as part of my program I don't look up images before hand of what I'm searching for. I don't want my impression skewed by what I'm supposed to see. All I go on is coordinates of where I should notice something and the type of object and maybe the size.

Even with my 20" I can be constantly amazed at how difficult an object can be when by magnitude it could be assumed to be easy and visa versa. Hang in there.

Bill


Thanks everyone for all your responses.

If 4236 is a Hershel 400 Object, I may have observed and sketched 4236 many years ago when I had an 8 in Dob. But I think the sketch book may have gotten lost or thrown away when we moved. And since I was about a hundred short of the Herschel 400 I don't have a certificate to know if I actually did bag 4236. I may try for it again sometime on a really clear night.

You have a good point Bill about not looking at photos of objects. I try to avoid even looking at them. I will look at sketches of galaxies. This seems to make me a better observer and aware of possible details and the possibilities of picking up details in galaxies like dark lanes and spiraling.
I'm in my 60's and I may not be able to see as much at low powers like 35X to 45X. Instead I often find my best viewing is at medium powers 70X to 100X. I guess this comes with aging eyes.
I can get over not seeing 4236, when in the same night I studied and enjoyed sights like the "Whale Galaxy" NGC 4631,
NGC 4565, and one I always study through my scope in the spring, M 104 the "Sombrero." And that's just to name a few.
I never could understand why anyone would want to hurry through these objects in some Marathon? There's lots of galaxies to see in the spring, but I like to just take my time and study and savor and sketch these objects.

#12 Sasa

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Posted 28 March 2014 - 06:00 AM

I saw NGC4236 only once. It was in 110mm refractor from my darker-site observatory. It was at 30x relatively well visible with averted vision as a thin line long about 10'. It was still visible at 66x, here two very faint stars in the galaxy body started to blink in and out.

I failed to see this galaxy from my light polluted backyard though.

#13 GlennLeDrew

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Posted 28 March 2014 - 08:26 AM

I've dimly glimpsed it throught my home-made right angle bino in the 20.8X60 configuration, on a quite dark spring night.

#14 Nick Anderson

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Posted 29 March 2014 - 03:11 PM

Here is my log of the object with my XT8 on February 28. I even tried using filters to see if I'd get a response similar to another low surface brightness Local Group galaxy, NGC 6822 (Barnard's Galaxy).

NGC 4236, galaxy in Draco: interesting galaxy; moderately difficult averted vision object; appears as a faint elongated glow; diffuse and surprisingly large; close to 15 arcminutes in length; oriented NNW-SSE; central region may be slightly brighter than its surrounding areas; SkyGlow and UltraBlock filters do not seem to help; viewed at 48x

-Nick Anderson

#15 Feidb

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Posted 29 March 2014 - 06:54 PM

I've observed it twice. Once on September 4, 2005 with my home-made 16-inch f/6.4 at 70X. At 5,200 feet, I saw an extremely faint, but large oval. I observed it again on August 23, 2008 with my commercial 16-inch f/4.5. At 7,400 feet, I saw a broad oval haze, again at 70X. This was before I got my 18mm EP which would've given me 102X and a bit more detail. I would've also tried 229X to eke out even more. Maybe next time.

#16 Matt Lindsey

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Posted 29 March 2014 - 08:15 PM

It's an H 400 II object.

My notes from 4/28/11 from SQM-L 21.1 skies: 12" Dob, 115X, moderately faint, v. large, edge-on with even brightness thru length of galaxy.

#17 nytecam

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Posted 31 March 2014 - 06:11 PM

My first attempt to image this very faint gxy tonight below - sky condition not its best - some HII regions appear recorded against Sloan DSS reference - hope it's of interest :grin:

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#18 nytecam

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Posted 01 April 2014 - 03:37 PM

Better transparency tonight for 65s exp + HII regions via Sloan DSS :grin:

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#19 Sarkikos

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Posted 03 April 2014 - 07:14 AM

I've spotted NGC 4236 through my 10" f/4.8 Dob at a yellow/green zone site. A faint sliver of ghostly light. It's in the H400 II list and is also one of Mullaney's Herschel Showpieces.

Mike

#20 David Knisely

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Posted 03 April 2014 - 12:59 PM

It's an H 400 II object.

My notes from 4/28/11 from SQM-L 21.1 skies: 12" Dob, 115X, moderately faint, v. large, edge-on with even brightness thru length of galaxy.


Well, it is on the Astronomical League's Herschel II listing, as there is no "Herschel 400 II" list for the Astronomical League's follow-on observing project. The Herschel 400 is the first program in the League's Herschel observing projects and the follow-on is the Herschel II (398 objects, as the alleged "cluster" NGC 2253 and the "nebula" NGC 1990 do not exist). Clear skies to you.

#21 Sarkikos

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Posted 03 April 2014 - 01:39 PM

A lot of observers seem to be using a list that doesn't exist. :thinking:

Herschel 400 II AKA "Astronomical League's Herschel II listing"

:grin:
Mike

#22 Sarkikos

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Posted 03 April 2014 - 01:44 PM

Here is an observation log for the "Herschel 400 II."

Herschel 400 II Observation Log

Mike

#23 Bill Weir

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Posted 03 April 2014 - 09:47 PM

But those lists were picked by someone (OK maybe a committee) in a club that is their opinion of objects on this list, http://obs.nineplane...schel/h2500.txt that are the best to observe. As I work my way along the W Herschel 2500 (not really that many) often when I hit one on either of the H400-I or H400-II I find myself thinking, "Why?" Then I will observe an object and find myself putting several exclaimation marks in my note and it won't be on either of the H400 lists. I'm enjoying for myself figuring out which to me are the best W. F. Herschel objects. When I'm finished it then I'll move on the John's list of DSOs.

I just want to look at everything. I hope this month to observe NGC 4236 with my 20" and look for those HII regions.

Bill

#24 Gil V

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Posted 03 April 2014 - 10:48 PM

David,

You are my absolute go-to guy when it comes to deep sky. Your guidance has greatly enhanced my deep-sky observing, especially this year.

But, I have to ask. What deep-sky objects are on your still-to-see list? Any particular unseen standouts that you'd care to share?

#25 David Knisely

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Posted 04 April 2014 - 02:15 AM

David,

You are my absolute go-to guy when it comes to deep sky. Your guidance has greatly enhanced my deep-sky observing, especially this year.

But, I have to ask. What deep-sky objects are on your still-to-see list? Any particular unseen standouts that you'd care to share?


There are so many things I want to go after that there would be no way to give even a partial listing of them. Usually, I just pick a field from MEGASTAR or Uranometria and go after every object plotted there. I will also refer back to the book The Arp Atlas of Peculiar Galaxies by Jeff Kanipe and Dennis Webb, as it is loaded with interesting and challenging targets. Then, there are the various Astronomical League observing projects that I wish to tackle, so there is just a lot to look for. Clear skies to you.






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