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NGC 772

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#1 uniondrone

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Posted 14 November 2012 - 02:51 PM

I think I might have spotted NGC 772 from my orange/red zone border observing site, but I'm not sure. What I saw looked stellar with a faint, but directly visible, whisp of light extending in one direction from the stellar object (galactic core?). Does this sound right?

#2 IVM

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Posted 15 November 2012 - 12:05 AM

Excellent observation! NGC 772 is indeed characterized by a small prominent core and one prominent arm extending in a very shallow arc from the N of the core to the WNW.

I believe I have only seen this galaxy with my f/5.5 Televue (pretty much exactly three years ago). I have no record of seeing any structure, and probably did not see any even from my elevated blue-zone site with the 4". What I write here about its structure is based on the DSS.

Curiously, NGC 772 is the most distant object in the Herschel 400 by redshift-independent estimates - 174 Mly. By redshift it is much closer to the pack at 98 Mly:
http://ivm-deep-sky....-distances.html

#3 uniondrone

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Posted 15 November 2012 - 12:17 AM

If what I saw was in fact NGC 772, it was pretty tough to detect. I really did think it was just a field star for quite a while. I was nudging the scope around to look for the galaxy when I saw something odd about one particular star. I thought that I saw something faint and fuzzy to one side of the star, I wasn't sure if it was real. After some staring I could eventually pick out a tenuous fuzzy extention. Still I was thinking that it could have been some sort of optical reflection or abberation that caused it.

I will definitely have to go back and check it out again, but at least I have a sense of what I am looking for now. Thanks for the feedback!

#4 Astrojensen

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Posted 15 November 2012 - 04:06 AM

This doesn't sound right. NGC 772 is one of the brightest H400 objects and is plain and easy to see in my 63mm Zeiss in a green/blue border zone. It is pretty large (compared to some of the other H400 stuff). There are no really bright stars nearby, but the core is quite bright, but is visibly larger than a star. If you didn't see that much, you sure didn't stand a chance to see its main spiral arm, which curves away to the NE (no, I didn't see the arm in the 63mm, nor the companion galaxy, NGC 770, a few arcminutes to the S).


Clear skies!
Thomas, Denmark

#5 uniondrone

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Posted 15 November 2012 - 11:35 AM

This doesn't sound right. NGC 772 is one of the brightest H400 objects and is plain and easy to see in my 63mm Zeiss in a green/blue border zone. It is pretty large (compared to some of the other H400 stuff). There are no really bright stars nearby, but the core is quite bright, but is visibly larger than a star. If you didn't see that much, you sure didn't stand a chance to see its main spiral arm, which curves away to the NE (no, I didn't see the arm in the 63mm, nor the companion galaxy, NGC 770, a few arcminutes to the S).


Clear skies!
Thomas, Denmark


Hello Thomas,

A couple of things to note: seeing is often bad enough in my region that stars are usually not pinpoint. Rarely have I gone above 150x in the last two years because the upper atmosphere is too turbulent. What I suspected might be the core of NGC 772 would probably have been visibly larger than a star from most locations, but might not have been from mine, since stars are often a bit bloated.

Secondly, the observation was from an orange/red zone border, with a very strong southern light dome. For comparison, M74 is a marginal observation on most nights. I think that M74 and NGC 772 have similar surface brightness, although NGC 772 has a brighter core. Is it possible that I saw the core and a whisp of light from the brightest part of the disc (which may or may not be the arm)? How bright is the arm relative to the core? The picture from the Digitized Sky Survey suggests that the arm isn't so much dimmer than the core. :confused:

I can't really say for sure what I saw, which is why I am here asking. :shrug: If you don't think what I saw was NGC 772, do you think that is is doable from my location?

#6 ensign

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Posted 15 November 2012 - 12:39 PM

If what I saw was in fact NGC 772, it was pretty tough to detect. I really did think it was just a field star for quite a while.


I had a similar experience with 772. Given the details of magnitude and size, I expected it to be a fairly easy find. I was using a C8 with a .63 reducer when going after this quarry as part of my H400 efforts.

Almost the first night after upgrading to an Edge HD 9.25 I found it with little trouble. I believe that the new scope transformed the object from looking like a field star. The halo was obvious in the 9.25.

I, too, deal with mostly fair-to-middling sky quality. That may have something to do with the difficulty in observing this object.

#7 Astrojensen

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Posted 15 November 2012 - 03:46 PM

The core of NGC 772 is a little smaller than M57, the Ring Nebula, but obviously fainter. I don't hope your seeing is bad enough that stars are bloated into blobs an arcminute or so across! The core is much brighter than the main spiral arm of NGC 772. The DSS images often show the spiral arms of many galaxies as deceptively bright, but it's a trick of the image, since the cores of most galaxies, even mag 13 ones, are heavily burned out on the photographic plates. It's quite a while since I observed both M74 and NGC 772 on the same evening, but from what I recall, NGC 772 was definitely the easier to see. M74 is devilishly dim, like a fainter M33.

Whether NGC 772 is doable from your location is something I can't really answer, since I'm not familiar with your location, but I'll go out the next chance I get and take a look at NGC 772, perhaps on a moonlit evening, with my 12", and let you know what it looks like. I can use a binoviewer, which will dim the view down to what a 10" might deliver.


Clear skies!
Thomas, Denmark

#8 uniondrone

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Posted 15 November 2012 - 04:46 PM

Thomas,

Thanks for your comments! Hmmm, M74 is devilishly difficult from my observing site, but I have done it on nights of good transparancy. I agree it is like a dimmer and smaller M33, which is also pretty tough from my observing site. I usually can see M33 without much trouble unless it's a below average night. If NGC 772 is easier than either of these, then maybe I didn't find it.

Although my seeing conditions are bad, stars don't ever appear like M57. On a very bad night at 150x, however, they might look like very small planetary nebulae. On an average night, stars will look soft starting around 120x, and grow consistently softer from there on up. If the entire core is about 1' in size, how much of that is visible under light pollution? Is it possible that under my conditions the core is a barely-visible 1' wisp with a bright center that is 10" or less?

#9 Astrojensen

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Posted 15 November 2012 - 05:02 PM

Hmmm, M74 is devilishly difficult from my observing site, but I have done it on nights of good transparancy. I agree it is like a dimmer and smaller M33, which is also pretty tough from my observing site. I usually can see M33 without much trouble unless it's a below average night. If NGC 772 is easier than either of these, then maybe I didn't find it.


That is what I suspect, though I've got no way to be 100% sure.

Although my seeing conditions are bad, stars don't ever appear like M57. On a very bad night at 150x, however, they might look like very small planetary nebulae. On an average night, stars will look soft starting around 120x, and grow consistently softer from there on up.



I think that's pretty normal. Sounds very much like it's around here, too. Last time I was out, 75x was pretty much the limit. Even at that magnification, stars were definitely small blobs.

Is it possible that under my conditions the core is a barely-visible 1' wisp with a bright center that is 10" or less?


That's certainly possible, although I think that the core is more easily visible than you suspect. What other galaxies have you observed? How does NGC 7331 look from your place, for example?


Clear skies!
Thomas, Denmark

#10 uniondrone

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Posted 16 November 2012 - 10:34 AM

That's certainly possible, although I think that the core is more easily visible than you suspect. What other galaxies have you observed? How does NGC 7331 look from your place, for example?


From my usual observing site, NGC 7331 is pretty much immediately obvious as soon as it enters the field of view. I see a fairly bright (by galaxy standards, at least) lens shaped slit of light that is presumably mostly the core. On a good night with some persistence, I can perhaps make out a faint relatively featureless zone around the core that is brighter than the background glow.

For comparison, NGC 1023 is also immediately obvious in the eyepiece, but NGC 891 is a notably more difficult, although I manage to view it routinely from this observation site. With M77, I see a stellar core and a sizable circular glow that encompasses it. I have already described my views of M33 and M74 in an above post. Based on this, how difficult would you expect NGC 772 to be?

Thanks again!

#11 Astrojensen

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Posted 16 November 2012 - 02:58 PM

Based on my memory of views in my 63mm, NGC 772 is a lot easier than NGC 891, but a wee bit more difficult than NGC 7331.


Clear skies!
Thomas, Denmark

#12 Feidb

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Posted 16 November 2012 - 09:44 PM

I saw a broad faint oval with a concentrated core at 70X. That was on September 11, 2010 from Cathedral Gorge State Park in central-eastern Nevada.

#13 Astrojensen

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Posted 19 November 2012 - 02:29 PM

Was out last night with the 12" under somewhat hazy skies and lots of ground fog. NGC 772 far from the meridian, setting in the west. Immediately visible in the 12" at 75x as a broad, slightly elongated fuzz. 150x showed a bright, stellar nucleus. The core had a rather well-defined edge and was sitting inside a much larger, far dimmer, round haze. NGC 770 nearby visible as a nearly stellar object at 150x. Very high surface brightness, slightly elongated. Surface brightness of the core and stellar nucleus was much higher than NGC 891. M74 had slipped too far down into the soup and was not observed.


Clear skies!
Thomas, Denmark

#14 Starman1

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Posted 19 November 2012 - 05:47 PM

NGC772 with 8" SCT:
Oval,diffuse edges,core lrg % of vis.Gal,faint but not hard,sml,brite,roundish oval,stellar nucl.,core more oval than gal.
NGC772 with 12.5" newtonian:
mod.sml, round-oval with straggling arm on one side of gal. (reminds me of v.small M101),stellar nucleus, large oval core,brite,brite core makes spiral nature v.difficult.

Overall, though this is the brightest galaxy in Aries, it is not the easiest to see, because it has an overall surface brightness lower than a few others. But the bright core makes it obvious in nearly any scope larger than 6". In much darker skies (say, blue zone), it's fairly easy in my 5".

Whereas NGC7331's core is not so bright (it has a more gradual brightness gradient), the much larger size and overall brightness of 7331 makes it FAR easier as a target.






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