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Distant Galaxies and Clusters

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#26 Pcbessa

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Posted 24 February 2019 - 06:33 PM

The limiting magnitude for a 10" in a relatively dark location like mine (Bortle 4) is about 14.5 to 15, depending on transparency and the object altitude on the sky. And up to magnitude 16 under very dark skies and excellent conditions.

Even a 6" reaches magnitude 15 under excellent conditions. So several quasars are theoretically available for those with that aperture.

These magnitude limits are at 100x or above.

Your suggestions are much appreciated!

Will go for them once the weather is again fine!

#27 quazy4quasars

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Posted 25 February 2019 - 01:55 PM

  What you say is true;  I believe you are a man after my own heart where QSOs are concerned, Pchessa!  But remember, I don't know your eyes, your skies, your level of expertise, etc; so I gave you a list of mildly challenging targets to start - per your request.  I wouldn't feel right suggesting a mag 15.0 QSO (The Parachute - though I considered it)  for a first attempt with 10", though I have suggested it is possible elsewhere on CN.  And Did you bag 3c273?  

 

  There's a fine line between encouraging one to test their limits- and setting one up for disappointment.  Most people will not ever try for mag 16.0 with 10". That's not to say it is impossible for everyone, but most will simply not detect such a source, not the first time, nor with direct (or averted) vision.  I'm seriously impressed you are pushing toward the "limits" and succeeding well - in Northern Scotland in February?  That's dedication for you.  Brrrrrr!



#28 Starman1

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Posted 25 February 2019 - 03:00 PM

I would note there is a big difference between a stellar limit and a DSO limit.

I have reached magnitude 17.35 (+/-) in my 12.5" for stellar points, but

I cannot honestly say I've seen any DSO fainter than magnitude 16.0.

The ones I've seen between mag. 15.5 and 16.0 were on exceptionally clear nights at my dark site.



#29 Mark326

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Posted 25 February 2019 - 03:20 PM

If imaging counts as Observing, NGC 499, 498,... a cluster of 5 or 6 galaxies ranging from 190-250MLY distant.  16-18 mag.  With a 6in RC.

 

If observering visual only.  A smudge of M31, faint haze of M33, and other Messier objects using averted imagination.  10dob.   My eye sight sadly leaves me wanting more, usually go the EAA to AP route of hobby.


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#30 Dave Mitsky

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Posted 25 February 2019 - 04:12 PM

The farthest objects that I've logged have been CTA 102, the Twin or Double Quasar (QSO 0957+561), and Einstein's Cross (QSO 2237+0305).
 

Dave Mitsky



#31 Pcbessa

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Posted 25 February 2019 - 08:43 PM

Thanks for the Andromeda Parachute suggestion.

 

I think it really nears the limit of what I could see with this scope (magnitude 14.5 to 15), although I have skies of Bortle 2 just 20min drive away, so there I could technically reach magnitude 16 at zenith under excellent conditions. I am quite glad to live in a quite remote and dark area, in the far north of Scotland.

 

Usually I feel more comfortable with magnitudes under 13. That's what show as a very faint fuzzy in my 10inch. A magnitude 12 galaxy shows more easily as a faint fuzzy but more readily seen. Anything of magnitude 10 is much brighter and beautiful. Except face on galaxies with low surf brightness.

 

I think I only saw magnitude 14 of Andromeda Parachute because it was a stellar point. It requires averted vision and I can only see like a third of the time or less. I do not think I could see any magnitude 14 galaxy, unless conditions are excellent

 

Skies here are usually quite fine and dark, but weather can be unpredictable. Two nights ago was good, tonight was really bad transparency (some high clouds). Its actually the warmest February on record. Imagine! Some nights have been a balmy +10C. Thats very unusual. But cold is obviously better for observation.

 

So due to high clouds and bad transparency I couldn't retry the Andromeda Parachute, though I had a look at the Abell 347 cluster in Lynx. But I only saw clearly its brightest member (a mag 12 galaxy). And only because it was straight at zenith. Its a cluster at 300 million light years away, and I could probably see 4 or 5 members.

 

I haven't got Virgo high in the sky yet, so I will wait a month until I try 3c273.

 

So far I saw:

  • Andromeda Parachute (still to be fully confirmed). Mag 14. 11 billion light years distance.
  • Abell 426 in Perseu. 250 million light years distance (NGC1275, 1272, 1278)
  • Abell 262 in Andromeda. 210 million light years distance (NGC679, 687, 708)
  • Abell 347 in Andromeda too. 210 million light years distance (NGC910, 906?)
  • Abell 1367 in Leo. 330 million light years distance (NGC3837, 3842, 3841, 3845, 3840, 3861, 3862, 3873)
  • Abell 347 in Lynx. 300 million light years distance (NGC2832, 2826?, 2839?)

I saw an average of 3 galaxies in each cluster, around mag 12 to 13, but in Leo cluster I could see 8 galaxies, as conditions were better when I saw that one (darker skies and cluster quite high in the sky).

 

A 10inch really opens the door to Abell clusters, they are mostly faint and one can see the brightest members. Probably one needs a much larger aperture, like a 16inch, to really start seeing nice clusters of galaxies.

 

But I feel a need to come closer to Earth. Tomorrow I plan spending some time observing details on the Local group! M81, M82, M33 and M31! First view of these was quite impressive but I need time to check their details.

 

Please feel free to keep adding any suggestions down to magnitude 14 smile.gif

 

 

  What you say is true;  I believe you are a man after my own heart where QSOs are concerned, Pchessa!  But remember, I don't know your eyes, your skies, your level of expertise, etc; so I gave you a list of mildly challenging targets to start - per your request.  I wouldn't feel right suggesting a mag 15.0 QSO (The Parachute - though I considered it)  for a first attempt with 10", though I have suggested it is possible elsewhere on CN.  And Did you bag 3c273?  

 

  There's a fine line between encouraging one to test their limits- and setting one up for disappointment.  Most people will not ever try for mag 16.0 with 10". That's not to say it is impossible for everyone, but most will simply not detect such a source, not the first time, nor with direct (or averted) vision.  I'm seriously impressed you are pushing toward the "limits" and succeeding well - in Northern Scotland in February?  That's dedication for you.  Brrrrrr!


Edited by Pcbessa, 25 February 2019 - 08:58 PM.

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#32 sgottlieb

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Posted 09 March 2019 - 08:00 PM

  Also, there is a "Superluminous Spiral Galaxy"  CGCG 122-067  in Leo,  at z~.089  that merits interest.  It's well placed right now, at 09 44 53.6 +22 53 6.4.   It is a LINER with an active nucleus to boot.  Going on the User Defined List  B mag from E.Flesch  (Million Radio/Xray Asociations Catalog) = 13.3;   WikiSky gives (USNO-R) = 11.8, so the V mag is likely about 12.6.   It's a very rare type of galaxy, actually the closest one known, at 1.2 Billion ly.

 

 It has (or had) a massive blue (star-forming) arms (that's a good thing) and a bright double nucleus. I think these Super Spirals will prove in time to be the results of Elliptical/Spiral/Starforming Galaxy close merges.  Wouldn't it be awesome to see one across more than a Billion light years of space-time?  Oh yes, it will. 

Quazy's post about CGCG 122-067 as a "Superluminous Spiral Galaxy" over a billion light years out caught my attention a couple of weeks ago.  I was particularly interested as I have an article coming out in the May issue of Sky & Tel on observing distant galaxies and quasars (over 1 billion light years).

 

I quickly found the 2016 paper in the Astrophysical Journal with this title by a group led by Patrick Ogle, an associated news release here, and Sky & Telescope's summary here.  Fifty-three "Super Spirals" were identified by mining the NASA/IPAC Extragalactic Database (NED).  The galaxies in the paper have diameters between 180,000 and 440,000 light years and are churning out stars at a furious rate of 5 to 65 solar masses per year. All of the spirals in the survey have distances from 1 to 3.5 billion light years (redshifts between z = .089 and z = .300).   The paper presents a table of basically the biggest and baddest spirals within 3.5 billion light years.

 

Generally, the most massive and luminous galaxies are found at the center of rich galaxy clusters (cD-type) and consist of bloated elliptical galaxies that have increased in mass and girth by cannibilizing their surrounding neighbors. Typical spirals (such as the Milky Way) might have a diameter of ~100,000 light years and produce the equivalent of 1 solar mass of new stars per year.  So the Super Spirals are quite rare.

 

Last weekend, while observing together with Jimi Lowrey on his 48", we looked for 10 of the 53 Super Spirals in the paper, and were successful with 7 of these (under SQM 21.7 skies).  As Quazy4quasars suggests, the brightest and nearest of the 53 is CGCG 122-067 (listed in the paper as SS 50 for "Super Spiral" and OGC 1559 for "Ogle Galaxy Catalogue").  This galaxy is located in northern Leo 0.9° south of 3.0-magnitude Epsilon Leonis. Assuming a Hubble constant of 70 km/sec/Mpc and other cosmology constants, its redshift of z = .089 implies a light-travel time is 1.2 billion years -- more distant than the Corona Borealis galaxy cluster. Normally, a spiral this distant would be very difficult to see, but this one has a diameter of 265,000 light years and a star-forming rate of 13 solar masses/yr. -- and should be visible in a 16- to 18-inch scope (I'm pretty sure the V mag is closer to 14.6 than 12.6, though).

 

In the 48" at 488x, I called it "fairly faint, small, round, ~20" diameter, very small bright core, stellar nucleus. A faint but easy mag 16.7 star is superimposed on the west edge. This galaxy actually looks like a spiral with a small core and nucleus!" On the SDSS image, this galaxy appears to be a merger with a double nucleus. We looked signs of the twin nuclei, but mistakenly assumed the superimposed star on the west side was the second nucleus. In any case it would likely require higher power to resolve, even in his monster scope.

 

Interestingly, 4 of the Super Spirals in the paper are late-stage major mergers and at least 10 seem to be in located in groups or galaxy clusters -- not surprising as this is typical way for large galaxies to bulk up, but most appear to be fairly isolated. So, how did they grow so massive and luminous?

 

The most distant one we managed was SDSS J121644.34+122450.5 (OGC 1606). This galaxy has a diameter of 250,000 light years, a redshift z = .257 and a light-travel time of just over 3 billion years. It was quite dim in the 48" (required averted) and about 15" in diameter.   Neither of us thought a spiral galaxy would be visible at this distance so this was an exciting observation.


Edited by sgottlieb, 09 March 2019 - 10:20 PM.

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#33 quazy4quasars

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Posted 10 March 2019 - 12:44 PM

  Many Thanks and congrats to you, Steve, and to Jim Lowrey for doggedly chasing down, and sharing your observations of CGCG 122-067 -and some of the other Super Spirals, with the 48".  Great work!  (...I'm jealous)  My extrapolated V estimate has proved wildly optimistic, but your observation of the huge star-forming spiral has definitely encouraged me to attempt to see it, in the 25"  -when I can get to a good dark site that isn't still snowed in!

 

  And regarding SDSS J121644.34+122450.5;  to visually detect any non-AGN Spiral Galaxy at  z>.25 is...just unheard of... amazing.  I think you guys have surely moved the goalposts with that one. Superb achievement!


Edited by quazy4quasars, 10 March 2019 - 03:57 PM.


#34 Pcbessa

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Posted 10 March 2019 - 02:36 PM

The last few nights I saw more distant galaxies.

 

I did not retry the Andromeda Parachute as I await to buy a Barlow to apply a magnification above 120x which is currently my highest option (I know it's ridiculously low!)

 

I observed one nice galaxy, Ngc2484, in Lynx, and it is 600 million light years. It was a relatively bright galaxy, seen clearly. A good jump in distance from the 300 million light year barrier from most Abell clusters I have seen.

 

Much fainter and harder to spot were Pgc5142525 and Pgc5064477 in Lynx and Leo (near ngc2532 and ngc3094), at 2 and 5 Billion light years away! In both cases I did see something in their locations with averted vision but starlike. I am confident because I used a star chart with stars down to magnitude 15 and there are no stars in the area (or just a couple mag15 stars) but the galaxies are supposed to be magnitude 13.  must repeat my observations again to double check these two reports. There is no information in their apparent size (actually there is no information on this galaxy other than the one listed on Sky Safari Plus). So I cannot be 100% sure I saw these galaxies.

 

I actually did a search on Sky Safary by galaxy, below magnitude 14, and listed them by distance. Interestingly I got several results above 1 billion light years, but almost all of them were too near bright stars! This is a suspicious coincidence! Why are the most distant bright galaxies listed all located near bright stars. Gravitational lensing?

 

I tried to see a few of them but could not, as the glare of nearby magnitude 6-7 stars did not allow me to see anything. Those two listed above were some of the exceptions.

 

Then as Virgo was rising, I went for 3C273 and it was extremely easy to find and spot as a normal magnitude 13 star. No difficulty for my 10". I wanted to see IC1101 (another far galaxy), but it was behind trees.

 

But with Leo, Bootes, Lynx, Camelopardis, Draco near zenith, I think I have many other choices to quasars. I definitively need to try to see Markarian 205 for instance. At the moment 3c273 stands as my most distant object seen with certainty.



#35 sgottlieb

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Posted 10 March 2019 - 07:26 PM

  Many Thanks and congrats to you, Steve, and to Jim Lowrey for doggedly chasing down, and sharing your observations of CGCG 122-067 -and some of the other Super Spirals, with the 48".  Great work!  (...I'm jealous)  My extrapolated V estimate has proved wildly optimistic, but your observation of the huge star-forming spiral has definitely encouraged me to attempt to see it, in the 25"  -when I can get to a good dark site that isn't still snowed in!

 

  And regarding SDSS J121644.34+122450.5;  to visually detect any non-AGN Spiral Galaxy at  z>.25 is...just unheard of... amazing.  I think you guys have surely moved the goalposts with that one. Superb achievement!

Thanks for the comments, Quazy.  We mentioned CGCG 122-067 to Howard Banich, who was just taking off to observe in the Oregon coastal mountains.  He tracked it down in his 28-inch f/4 and also saw the nearby dim star and a single nucleus.  But he mentioned that, although faint, CGCG 122-067 was visible without much difficulty in a friend's 16-inch at 187x.   This was in 21.5 SQM skies and good seeing.  So, it seems very likely to be visible in a 14-inch in similar conditions.



#36 bertandlaville

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Posted 11 March 2019 - 09:50 AM

Hi All,

 

Different is to observe a quasar, enhanced by a gravitational lensing, and an Abell Galaxy Cluster, the members of which are all not stellar points.

For me the most distant AGC I have ever seen is the Great Corona Borealis Cluster, AGC 2065, at 500 millions l.y., with a lot of galaxy between m15v and more.

 

Here is my drawing with a 48" of Haute Provence Observatory, in an average sky (SQM 21.5, NELM 6.5v)

Report: http://www.deepsky-d...2065/dsdlang/fr

 

Clear skies

Bertrand

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AGC-2065-T1200-BL-labelled.jpg


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#37 Araguaia

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Posted 11 March 2019 - 10:08 AM

I would note there is a big difference between a stellar limit and a DSO limit.

I have reached magnitude 17.35 (+/-) in my 12.5" for stellar points, but

I cannot honestly say I've seen any DSO fainter than magnitude 16.0.

The ones I've seen between mag. 15.5 and 16.0 were on exceptionally clear nights at my dark site.

I have a little less aperture, a lesser quality mirror, and a lot less experience than you.  With our 12" I cannot recall ever seeing anything fainter than mag 14.5, and that was a planetary nebula - star-like.  The faintest galaxies I detect with confidence are in the high 13s.  But in order to see any shape or detail the limit is more like mag 12.5 for me.

 

Then again, while I often spend hours observing the faintest details in a brighter galaxy, I rarely spend too much time trying to simply detect a very faint one.



#38 Starman1

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Posted 11 March 2019 - 10:41 AM

Hi All,

 

Different is to observe a quasar, enhanced by a gravitational lensing, and an Abell Galaxy Cluster, the members of which are all not stellar points.

For me the most distant AGC I have ever seen is the Great Corona Borealis Cluster, AGC 2065, at 500 millions l.y., with a lot of galaxy between m15v and more.

 

Here is my drawing with a 48" of Haute Provence Observatory, in an average sky (SQM 21.5, NELM 6.5v)

Report: http://www.deepsky-d...2065/dsdlang/fr

 

Clear skies

Bertrand

http://www.deepsky-drawings.com

 

 

AGC-2065-T1200-BL-labelled.jpg

Bertrand,

You did much better than you thought.  Abell 2065 in Corona Borealis is at 1 billion light years distance!



#39 Redbetter

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Posted 11 March 2019 - 02:14 PM

 

Much fainter and harder to spot were Pgc5142525 and Pgc5064477 in Lynx and Leo (near ngc2532 and ngc3094), at 2 and 5 Billion light years away! In both cases I did see something in their locations with averted vision but starlike. I am confident because I used a star chart with stars down to magnitude 15 and there are no stars in the area (or just a couple mag15 stars) but the galaxies are supposed to be magnitude 13.  must repeat my observations again to double check these two reports. There is no information in their apparent size (actually there is no information on this galaxy other than the one listed on Sky Safari Plus). So I cannot be 100% sure I saw these galaxies.

 

I actually did a search on Sky Safary by galaxy, below magnitude 14, and listed them by distance. Interestingly I got several results above 1 billion light years, but almost all of them were too near bright stars! This is a suspicious coincidence! Why are the most distant bright galaxies listed all located near bright stars. Gravitational lensing?

Neither of those PGC's resolves in LEDA or anywhere else I tried.  You would need to provide coordinates to be able to ID them.  I don't know what Sky Safari uses or reports but I doubt there are any 13th visual or B mag galaxies with PGC numbers in the 5 million range...and perhaps not even in the 100,000+ range.  My guess is that this is some sort of very long wavelength value being reported.

 

I doubt you will see any 2 or 5 billion light year galaxies with a 10" even in pristine conditions.  Quasars I don't know, but you would likely need to see stars far dimmer than 15.  Look the positions up in Wikisky's field.  That will give you an idea whether or not it is even possible. 


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#40 Redbetter

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Posted 11 March 2019 - 02:25 PM

Bertrand,

You did much better than you thought.  Abell 2065 in Corona Borealis is at 1 billion light years distance!

 

I didn't do a good job logging that one.  I only logged 6 for certain, but I know I saw at least twice that many...just didn't note specific positions so I didn't log them, perhaps 3 times that many since there were some in the northern group that I saw, but I didn't log any there at all.  I need to prep. and revisit.  This was with the 20" in the White Mountains.



#41 quazy4quasars

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Posted 11 March 2019 - 04:23 PM

  I tried to look up those PGCs too, they were not in NED, SIMBAD or HEASARC - makes me wonder.

 

  From first hand experience I can agree that SkySafari uses a LOT of useless magnitude data. Redbetter called it first; they use IR mags instead of V sometimes.  To be fair; often there are no published V mags for distant galaxies.  I would always take them with a big grain of Salt.   No offense, SkySafari. Then there's the "Peak vs. Integrated" magnitude issue, too. It's a mess!

 

  When I come across a possible target for deep viewing during my online rambles, I look at the available imagery (if the image is saturated, or nearly so, I figure I can probably see it!) as well as the published data from several sources.  In doing so, you will find big - huge - disparities, but you will also find that there are a few gems buried amidst all the seemingly "junk" data. 

 

  NGC 2484 looks promising:  clearly a very bright, dense elliptical, and it has an AGN (3c189) at its core.  Thanks Pchessa!

 

  Even with images, remember; they are from long exposures, often partly (even completely)  in wavelengths we can't even see, taken with really big telescopes.  One of my biggest gripes with SDSS is their ugriz color mapping, I won't go into that here. 


Edited by quazy4quasars, 11 March 2019 - 04:23 PM.


#42 Starman1

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Posted 11 March 2019 - 04:30 PM

There are magnitudes listed for the brightest 23000 galaxies in the RC3 of Vaucouleurs.

Not all V magnitudes are listed, but B magnitudes are usually given, as well as B-V.

Don


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#43 Pcbessa

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Posted 11 March 2019 - 06:10 PM

Thanks to let me know that the world of galaxies is full of wrongly reported visual magnitude. I can totally understand that, and that could explain why I could not see any fuzzy light in the location pinpointed in Sky Safari Plus, despite the bright visual magnitude.

 

I can also understand if there are gross errors in reporting their distances.

 

In any case, because who knows if these galaxies are indeed that far and that bright, here is the data from Sky Safari:

 

PGC 5064477

SDSS 100226.24+143618.2

Mag reported as +12.9

Distance reported as 5B ly

RA 10h 03m 27.4

Dec +14  30' 46.4''

 

PGC 5142525

SDSS 080856.34+324419.2

Mag reported as +11.9

Distance reported as 2B ly

RA 8h 10m 7.95

Dec +32  40' 53.7''

 

If anyone can confirm or reject some of these data, please let me know!

 

With many thanks!

 

Until then, my most distant observed (confirmed) object will remain as 3C273. And my most distant confirmed galaxy as NGC2484 at 600 million light years.

 

PS: Starman, I searched for these two PGC galaxies on RC3 catalogue and I could not find them. Only located other PGC galaxies with smaller (5 digit) catalogue numbers.


Edited by Pcbessa, 11 March 2019 - 06:27 PM.


#44 Redbetter

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Posted 11 March 2019 - 06:42 PM

Thanks to let me know that the world of galaxies is full of wrongly reported visual magnitude. I can totally understand that, and that could explain why I could not see any fuzzy light in the location pinpointed in Sky Safari Plus, despite the bright visual magnitude.

 

I can also understand if there are gross errors in reporting their distances.

 

In any case, because who knows if these galaxies are indeed that far and that bright, here is the data from Sky Safari:

 

PGC 5064477

SDSS 100226.24+143618.2

Mag reported as +12.9

Distance reported as 5B ly

RA 10h 03m 27.4

Dec +14  30' 46.4''

 

PGC 5142525

SDSS 080856.34+324419.2

Mag reported as +11.9

Distance reported as 2B ly

RA 8h 10m 7.95

Dec +32  40' 53.7''

 

If anyone can confirm or reject some of these data, please let me know!

 

With many thanks!

 

Until then, my most distant observed (confirmed) object will remain as 3C273. And my most distant confirmed galaxy as NGC2484 at 600 million light years.

 

PS: Starman, I searched for these two PGC galaxies on RC3 catalogue and I could not find them. Only located other PGC galaxies with smaller (5 digit) catalogue numbers.

SDSS 100226.24+143618.2 is well over a degree from NGC 3094

There appears to be a tiny galaxy at that position in the DSS2 images, and plotted as an 18.15 mag star by USNOA2 catalog.  There is glare across it in SDSS III.  The magnitudes reported by LEDA for it in UV, visual, etc. are clearly bogus.  This one would likely be impossible in a 32".

 

 

SDSS 080856.34+324419.2 is about two degrees from NGC 2532 and appears as about a 20th magnitude spec.  I suspect that the B magnitude listed is a typo of some sort...the U mag is 21.4.

 

Neither would be visible in a 10".



#45 Starman1

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Posted 11 March 2019 - 07:00 PM

Research the galaxy you are interested in in:
NASA Extragalactic Database (NED),
and
SIMBAD.
If the info you need isn't there you probably won't find it.
Both databases have some errors and magnitudes are the most likely.
Part of the reason is that professionals are not, basically, interested in magnitude estimates except, perhaps for determining the size of the objects by using the magnitude 25 isophote.
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#46 quazy4quasars

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Posted 11 March 2019 - 08:44 PM

   Here's one site that will get you data from, and link you to, both. As well as a bunch of other catalogs and imagery. I may have already mentioned it on this thread:

 

http://cdsportal.u-strasbg.fr/

 

That ought to keep you busy - at least till moonset. smile.gif

 

The only way of accurately determining the distance to these really deep Galaxies, especially the ellipticals- is by their spectral redshift. They are way too far away to use cepheids... Many of them still haven't had their spectroscopy exam, even the bright ones. They are myriad, and the sky is very big and full of wonders.


Edited by quazy4quasars, 11 March 2019 - 09:13 PM.


#47 Pcbessa

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Posted 12 March 2019 - 09:03 AM

This very clear now. I know not to trust the magnitudes reported by Sky Safari.

Anyways my original motivation was to search for very far away galaxies below magnitude 14, which are doable for a 10".

Besides quasars, IC1101 and NGC2484 are two examples. Are there more?

Any galaxy member of the Corona Borealis cluster, bright enough for a 10"?

#48 Starman1

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Posted 12 March 2019 - 09:29 AM

This very clear now. I know not to trust the magnitudes reported by Sky Safari.

Anyways my original motivation was to search for very far away galaxies below magnitude 14, which are doable for a 10".

Besides quasars, IC1101 and NGC2484 are two examples. Are there more?

Any galaxy member of the Corona Borealis cluster, bright enough for a 10"?

I think the brightest members are below m.15, so probably not unless you have a pristine high altitude site.



#49 sgottlieb

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Posted 12 March 2019 - 11:07 AM

LEDA has an internal number for all objects, even when they haven't assigned an "official" LEDA designation.  The internal number can't be searched in professional online catalogues such as NED and SIMBAD or even LEDA, so they're pretty useless, but for some reason SkySafari has adopted them.

 

For example, in the case of PGC 5064477, you can't search for it under that name, but if you look up SDSS 100226.24+143618.2 (same object), you can find the internal number PGC 5064477 listed on the right side of the top line next to the ALADIN image.  In any case, as Redbetter mentioned, the SDSS magnitudes are totally bogus probably due to the nearby bright star that floods the field.


Edited by sgottlieb, 12 March 2019 - 11:37 AM.

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#50 quazy4quasars

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Posted 12 March 2019 - 01:24 PM

This very clear now. I know not to trust the magnitudes reported by Sky Safari.

Anyways my original motivation was to search for very far away galaxies below magnitude 14, which are doable for a 10".

Besides quasars, IC1101 and NGC2484 are two examples. Are there more?

Any galaxy member of the Corona Borealis cluster, bright enough for a 10"?

 There probably are other galaxies at z~.07 that would be barely perceptible in 10" under excellent conditions, with practise, great patience and some "averted imagination" but none brighter than 14 in V. at least, none that I can find.  I say "probably" because their distances have been estimated by photometry; not spectra. Sometimes those estimates prove fairly accurate but are often seriously off.  Also, these galaxies are not point sources, so their light is not as concentrated as a QSO, but spread out, and somewhat less obvious to direct vision...

 

The Brightest Corona Cluster members are around mag 15, probably Averted Vision at best in 10", at medium or high power. It really depends on your eyes and the sky where you observe.  It's a reach. A Billion Light years is a long way out- Beyond that we are mostly in the realm of the AGNs; BL Lacs, Seyferts, QSOs, even with the biggest amateur telescopes.  


Edited by quazy4quasars, 12 March 2019 - 02:04 PM.



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