Thunderhead
professor emeritus
Reged: 08/27/05
Posts: 562
Loc: Melbourne, Australia
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This morning I just broke my record using my 10" dob....
I spotted NGC 5291 in Abell 3574 at Mag 14.2, and I glimpsed its companion MCG-05-33-005 (Sea Shell Galaxy) which is no doubt fainter as I could hold it in view only 50% of the time.
I also successsfully viewed IC 879, which is listed at 14th magnitude.
This was from suburban skies, NELM around +4.5-5.
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SAB - Melbourne, Australia
GSO 10" F5 Dob with flocking & dewshield
12" (304mm) F4.6 truss dob with premium optics
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Never
super member
Reged: 11/22/05
Posts: 109
Loc: Finland
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With the "faintest" you have plenty to choose from. You have different types of magnitudes, surface brightness, type of object, purely faintest you've seen visually and so on.
For example:
NGC 5291 @ 13.9 (v) magnitude and surface brightness 13.9
MCG -5-33-5 @ 14.7 (v) magnitude and surface brightness 13.3
Megastar lists 5291 @ 15.1 magnitude without surface brightness. As for -5-33-5... 18.0 magnitude and surface brightness 12.6.
So let's say faintest I've seen from the first constellation in the list... G73 in M31. That's close to mag 15 or something with a 10".
/Jake
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Jaakko Saloranta - Some basic sketches.../
8" Orion DSE
4" Sky-Watcher
3" Konus RFT
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Mattias
super member
Reged: 08/22/07
Posts: 100
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My record is 11.9 (NGC 3389 in Leo) according to Sky Atlas 2000 Companion. When it comes to stars I've been at the 14th magnitude while looking for R CrB.
My telescope is a 200mm (nearly 8") reflector.
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melonman
sage
Reged: 01/15/07
Posts: 265
Loc: NW. Minnesota
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like so many things, it is complex. My skies are moderately light polluted and I don't use any filters in the 12" 304mm dob. I can tell you I got pretty frustrated trying to to see NGC 147 a galaxy in Andromeda even after finding NGC 185 beside it. Now Steve Gottlieb describes this galaxy with an 8 inch though he calls it pretty faint. The NGC IC project lists NGC 185 as mag 9.3 and NGC 147 as mag 9.6 but they are respectfully, 14.4 and 14.6 surface magnitude. By contrast, a galaxy like 3373 in Leo is a "nice little" galaxy in the 12 inch from my area even though its total magnitude is 11.8
but its surface mag. is 13.1.
Finally, I'm currently adding more galaxies to a laminated star chart I have made that is about 1.2 meters by.6 meters and trying to add about 500 galaxies to the 200 or so on the chart which I have pretty much seen. Any one have a rule of thumb for minimum total mag and minimum surface mag? I don't want to hijack your thread Thunderhead
but the truth is your question may help me answer mine.
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stevecoe
"Astronomical Tourist"
Reged: 04/24/04
Posts: 2862
Loc: Arizona, USA
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The other thread about observing lists contains the SAC database. Some years ago I added the surface brightness along with the integrated magnitude so you can tell what is the faintest object seen. This is from Dr. Harold Corwin, one the folks instrumental in creating the NGC/IC Project.
In answer to your question, I saw galaxies in the Coma Galaxy cluster that were 18.9 magnitude with the "Yard Scope" a 36 inch f/5.
Fun;
Steve Coe
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TeleVue 102 refractor on CGEM mount
9.25 inch Celestron SCT
Author "Deep Sky Observing" Springer-Verlag
Author "Nebulae and How to Observe Them" Springer
Canon Xt astrocamera with Hutech modification
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Achernar
Postmaster
Reged: 02/25/06
Posts: 5211
Loc: Mobile, Alabama, USA
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The faintest objects I have ever seen were the globular cluster Palomar 12 in Capricornus and a group of galaxies more than 2 billion light years away. Both were seen through an 18-inch Dob from a very remote and dark site in Alabama.
Taras
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15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
One curious cat
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1312
Loc: Austin, TX
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The faintest or most distant? The faintest can be very hard to quantify. The visibility of any object depends on its apparent surface brightness (surface brightness with the current equipment, sky conditions, ect) its apparent size (dependent on magnification), and of course the observer. So if you want the faintest object... there is a whole continuum of objects that can be considered faint. If you’re looking for the faintest total integrated magnitude, we’d be talking about a star, since stars, as condensed points, are the easiest objects to see at a specific total integrated magnitude. However, at any certain surface brightness, there is a certain SIZE the object has to be before the brain can perceive it. You take size and surface brightness and you get total integrated magnitude.
So, to make a long story short, any one of probably a thousand objects I’ve seen that are just on the threshold of visibility could be considered the faintest object I’ve ever seen.
I guess I could give an example of some of the faintest galaxies I’ve ever seen:
Some of the faintest and most distant objects I've seen were reported in my observing report for 9/8/2007:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1838172/page/15/view/collapsed/sb/5/o/all/fpart/1
The most distant GALAXY I reported in that report was 1.9 billion light years away. However, since then, I've seen some galaxies in a couple galaxy clusters even more distant than that- I just never wrote up an observing report for them. In about half the cases, these galaxies are so faint they are not even plotted on Megastar- however, they are quite doable with an 18" scope and very dark skies. Supposedly, some of them are fainter than magnitude 17 or 18, but I never believed any of the magnitude estimates for very faint objects and I certainly don't believe those. I believe these objects are no fainter than magnitude 17.0 or so.
Yes, I know I can see farther looking at quasars (and have), but I feel that super-luminous inner edges of accretion disks surrounding supermassive black holes don't count 
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
Edited by tatarjj (02/19/08 09:28 AM)
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3524
Loc: Doylestown, PA
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Going along with the 'surface brightness' aspect: The faintest I've seen (from a dark site) is the very outer portions of M31, the disk area past the dark dust lanes that fade into the sky background. Same with any galaxy.
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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Alvin Huey
Carpal Tunnel
Reged: 10/18/05
Posts: 1870
Loc: NorCal
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John T said it very well! There are many many variables. The listed magnitude is just a number and many are not even relative to each other.
But to answer the basic question...and off the top of my head. It would be two members of Hickson 50 with a third suspected through my 30" StarMaster..."only" two simultaneous members of Einstein's cross through my 22" reflector.
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Tom Polakis
scholastic sledgehammer
Reged: 12/20/04
Posts: 816
Loc: Tempe, Arizona
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I'll agree with the sentiment that the numbers might not be meaningful. When I was working through the Local Group galaxies with my 13-inch scope, I came across some dwarf galaxies that are no more than a very slight change in the sky brightness. They could be seen only by sweeping across the field at my lowest magnification.
Often these dwarves are named after the constellation. The Sculptor Dwarf is very difficult, but definitely visible. Up north are the Draco and Ursa Minor Dwarf galaxies. The Ursa Minor dwarf was right at the edge of detectability in my 13-inch. Not sure a larger scope would help in cases like these, as you can't make the magnification any lower with them without running into exit pupil issues.
Tom
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Tom Polakis
Tempe, AZ
Visual observing, DSLR photography, lunar & planetary imaging
http://www.pbase.com/polakis/
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RRaubach
AstroCowboy
Reged: 01/26/05
Posts: 2173
Loc: Douglas (Converse County),WY
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Using my TMB203---Palomar 12.
With the Discovery 12.5" Dob--G219 in M31 @ V(t):15.4.
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Rodger
Meade SN-10 (UHTC) on Tak EM-200 mount/Antares rotating rings. Moonlite focuser.
Parallax 14.5" Newtonian on HD 200 mount (arriving soon!) w/ conical Royce mirror.
TMB 203 f/7 APO refractor on Tak NJP-160 mount.
Discovery 12.5" PDHQ
Schneider 18x80 "Flakfernrohr" binoculars/tripod mounted. Canon 15x50 IS binoculars
Unihedron Sky Quality Meter
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AlanK
professor emeritus
Reged: 01/26/07
Posts: 521
Loc: Auckland, New Zealand
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Well done with your observations.
Faintest galaxies seen so far in my new 18inch are 17.0 mag and 15.5-16.0 in my 12 with NLM 6.0 skies. These limits are for galaxies visible at least 50% of the time with averted vision. I'd think that small mag 15.0 high surface brightness galaxies should be possible in your 10 provided the seeing & transparency are good and a moderate/high power is used.
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Clear skies!
18 inch f4.5 Obsession #1637
12 inch f5.4 reflector
Just another frozen astronomer
Kumeu Observatory
Auckland NZ
7,379 deep sky objects incl 4,724 ngcs
Who dares - observes!
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stevecoe
"Astronomical Tourist"
Reged: 04/24/04
Posts: 2862
Loc: Arizona, USA
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Tom;
The way I hear from Brian Skiff and other experts is that there is no consistency about how the magnitudes of these galaxies are determined. That there are lots of variables about the filter type on the photometer. Some are take from an old film shot, like the Palomar Sky Survey or others. There is no one and only one meaning to the term "magnitude" when applied to what you will see at the eyepiece.
Of course the reason is that it does not matter to professional astronomers. As long as the data that is gathered is useful to them, there is little meaning for a professional when it comes to "visual magnitude".
At least that is what I hear;
Steve Coe
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TeleVue 102 refractor on CGEM mount
9.25 inch Celestron SCT
Author "Deep Sky Observing" Springer-Verlag
Author "Nebulae and How to Observe Them" Springer
Canon Xt astrocamera with Hutech modification
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galaxyman
Carpal Tunnel
Reged: 04/04/05
Posts: 1539
Loc: Limerick, Pa
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In the TMB 8" F/9 refractor seeing a couple galaxies in Hickson 56 (near Ngc 3718).
In the 22" f/4.5 dob seeing a number of galaxies in the Corona cluster Abell 2065.
Karl
E.O.H.
Chesmont Astronomical Society
Telekit (Swayze optics) 22" F/4.5 Dob
Homemade (Parks Optics) 12.5" F/4.8 Dob
TMB 8" F/9 Refractor(The Beast)
Antares 6" F/6.5 Refractor(Mini-Beast)
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So many galaxies, so little time!
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AlanK
professor emeritus
Reged: 01/26/07
Posts: 521
Loc: Auckland, New Zealand
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Steve
I hope I'm not drifting too much off topic in this thread with this question but from a purely visual observing point of view, is there a standard source we can quote visual magnitudes from when making comparisons of what is seen through different apertures? I've seen magnitudes given in many different ways (V - Visual), (B - Blue), (P - Photographic) and others calculated from photometric measurements.
Would V - Visual be closer to what is perceived by the eye or would it be B - Blue as the eye is more sensitive to that end of the visible spectrum?
Also as a good example, there are some differences in the given 'magnitude' for NGC 5291 from well known sources:
Guide 8.0 - 14.9
Skymap Pro - 13.9
Deepsky field guide - 14.1 (V)
Starry night Pro - 15.5
Are any of these sources more widely accepted than others?
Alan
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Clear skies!
18 inch f4.5 Obsession #1637
12 inch f5.4 reflector
Just another frozen astronomer
Kumeu Observatory
Auckland NZ
7,379 deep sky objects incl 4,724 ngcs
Who dares - observes!
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F.Meiresonne
Post Laureate
Reged: 12/22/03
Posts: 3632
Loc: Eeklo,Belgium
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True, it's difficult to be sure of magnitudes. Different sources report different data.
Actually i only use them to get some hint of the brightness.
For galaxies it's even more difficult,for that you can better rely on the surface brightness....wich can be way lower then the visual magnitude..
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Freddy Meiresonne
Obsession 18 inch #1638
Orion Optics 8 inch F/4.5 -1/8 wave optics -Vixen GP-E
22x85 Helios Apollo (=GO SS)
15x70 TS Marine (=Obie Ultra)
10x60 Helios Quantum 4(= Obie Mariner)
10x50,8x40 Helios Nature sport plus
Eyepieces in use :Pan 35,24,19, N13T6, Pentax 10 XW, N9T6, Ultrascopic 7.5, TV2, BGO 12.5 and 9 mm
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giorgosgr
super member
Reged: 03/11/05
Posts: 122
Loc: Kalamata Greece
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I think "most difficult" would be a better question... faint for DSO is as correctly said difficuld to quantify.
I consider some objects as very difficult through my 8" f/4.5 dob.
JnEr1 planetary in Lynx (O-III filter used), IC2574 in Ursa Major (large and faint, neglected object) and NGC7492 globular in Aquarius.
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Homemade 8" f/4.5 dob
Orange Celestron 8
6" f/8 equatorial newtonian
Vixen 80mm f/11.4 refractor
Vixen A80SS
etx-70
http://starobserver.wordpress.com
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BillFerris
Carpal Tunnel
Reged: 07/17/04
Posts: 2983
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Quote:
... is there a standard source we can quote visual magnitudes from when making comparisons of what is seen through different apertures? I've seen magnitudes given in many different ways (V - Visual), (B - Blue), (P - Photographic) and others calculated from photometric measurements.
Would V - Visual be closer to what is perceived by the eye or would it be B - Blue as the eye is more sensitive to that end of the visible spectrum?
Also as a good example, there are some differences in the given 'magnitude' for NGC 5291 from well known sources:
Guide 8.0 - 14.9
Skymap Pro - 13.9
Deepsky field guide - 14.1 (V)
Starry night Pro - 15.5
Are any of these sources more widely accepted than others?
Hi Alan,
The best online source of photometric data on galaxies is the NASA/IPAC Extragalactic Database: NED. The data are a little buried but once you get used to the interface, it's pretty easy to look up the published photometric data on many thousands of galaxies.
For example, the second column from the left on the home page is labeled, "Data." If you click on the "Photometry & SEDS" link and enter, "NGC 7479," in the search, you'll get a list of published photometry in different bands for that galaxy. The visual (V_t) band photomemtry is 10.85. That's NGC 7479's brightness for visual observers.
You'll find visual magnitudes for the brightest few thousand galaxies on NED. For the remainder that are within reach of amateur telescopes, many have published blue (B_t) band photometry. Blue band photometry is typically fainter than visual by about 0.8 magnitude. NGC 7479's blue band photometry (B_t) is 11.60, which is 0.75 magnitude fainter than the visual band photometry. The Whirlpool galaxy (NGC 5194) has a visual magnitude of 8.36 and a blue magnitude of 8.96. As you can see, the 0.8 magnitude conversion factor from blue to visual is only an estimate.
For the faintest galaxies, you may not find either visual or blue band photometry. But if there's 2MASS J band photometry, it's still possible to do a conversion to visual. According to Brian Skiff, a very rough conversion from J band (2MASS) photometry to visual is to add "about 2" magnitudes to the J_total data. For example, if we look at the published photometry for NGC 5291, there is no V band data. The blue (B_t) magnitude is 14.09 and the J_total magnitude is 10.26. Subtracting 0.8 magnitude from the B_t gets us to 13.29 magnitude. Adding 2 to the J_total brings us to 12.26 magnitude. Due to its distance from us, NGC 5291 is probably reddened a bit more than the better-known brighter galaxies. So, the conversion from B_t to visual is probably closer to a full magnitude. That takes us to 13.09 magnitude for an estimate in the visual band, which is probably a reasonable guesstimate; about 13.0 magnitude.
Bill in Flag
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Grand Canyon Adventure
Lowering the Threshold
18" Obsession
4.5" Meade 4500
10x50 Swift Audubon
Cosmic Voyage
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Illinois
professor emeritus
Reged: 12/18/06
Posts: 731
Loc: near Chicago, Illinois USA
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Faintest galaxy in my backyard is NGC 7331, only a few miles from Chicago! Bad light pollution!
Several 13th mag. Galaxies on my 16" Lightbridge near Dixon in Illinois. Yellow Zone light pollution! I will try to see if I can spot fainter as 14th mag. galaxy this Spring!
To see faint objects is depends on light pollution levels! Darkest and clearest night will push much more fainter to see! You see fainter galaxies on 10 " telescope in the dark and clear night than 16" telescope in the light pollution!
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Astronomer since 1975!
Orion 80mm ED refractor and
iOptron CubePro mount
Meade 16" Lightbridge Dobsonian
Orion 10" SkyQuest Classic Dobsonian
Tele Vue Eyepieces
Canon EOS XS 1000D
Orion Planetary 5 mm and
Orion Expanse Wide-Field 6mm eyepiece
4.5" F5 Reflector since 1982!
Orion Narrowband and SkyGlow filters
Member of IDA, let's fight light pollution!
Old Edmund 6"F8...donated to cousins
Super Polaris C8...donated to Byron Observatory in Illinois
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Gunner
professor emeritus
Reged: 06/20/06
Posts: 541
Loc: Bellville,Texas
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Faintest object for me was NGC 6888 Crescent Nebula at the Central Texas Star Party in August, looking through the 12".
Gave several others there a view that had never seen it but had photographed it.
Allen
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Orion 190mm Mak-Newt w/Orion 80ED Guidescope
Orion XT12i w/ Moonlite Cr-2 and Flocked
Orion 8" Reflector Flocked
Orion Atlas EQ-G mount
Orion Autoguider
Orion X-Y Guide Star Finder
Canon EOS Rebel XTi ( un-modified )
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