Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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I've always wanted to know this. How far are we looking? Let's say under a dark sky with good seeing. What are some of the distance records for different people and their telescopes?
I remember clearly seeing M87 in my 8" SCT under Bortle Red Skies. It's supposed to be over 50 million light-years away. That's my personal record. (Laughable!)
That's the kind of viewing I mean however. A clear sighting. Not the threshold of vision type of seeing, because that usually takes thousands of hours of telescope experience to be able to pick out those faint grey shapes.
So how far can an 8" typically see? How about an 11" or 14"? Or an 18" or 22" or whatever inch? Thanks people. This topic has always fascinated me. 
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Celestron CPC 1100
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4115
Loc: Ireland
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Mrk421 is probably doable with an 8". Wikipedia lists it at 360 million light years distant.
APM08279+5255 is probably the champ at a staggering 11 to 12 billion light years. It's a bit dimmer though, probably needing in the range of 10" or 12" under a dark sky.
Cheers,
-- Jeff.
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4115
Loc: Ireland
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Oh, and I've heard 3C273 can be done with a 4" refractor. (Wikipedia has it at 2.44 billion light years.)
-- Jeff.
PS: I should mention those are all visual. I think Nytecam has taken pictures of APM08279+5255 with an 70mm ETX.
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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Thanks Jeff. That's even further than I could have imagined!
Quote:
PS: I should mention those are all visual.
I should have mentioned that in my original post. Visual is what I am mostly interested in.
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Celestron CPC 1100
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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PeterSurma
super member
Reged: 08/24/06
Posts: 122
Loc: Heidelberg, Germany
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Deepest objects are always quasars, because they have maximal surface brightness (well, they are stellar !) and among the most luminous objects in the universe.
Here is a 15.2mag quasar in UMa at z=3.9, which translates to roughly 12 billion lyrs - should be feasible in a 14+ inch ... :-)
APM08279 0827+523 at coordinates 08 31 42 +52 45 18
Edited by PeterSurma (10/13/09 04:16 PM)
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Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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That's another suggestion that's darn near the edge of the known universe! I thought only massive Dobs or observatories could pull that off.
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Celestron CPC 1100
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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Dave Mitsky
Postmaster
Reged: 04/08/02
Posts: 10499
Loc: PA, USA, Planet Earth
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I've seen 3C 273 through my 101mm Tele Vue refractor from a very dark site. I haven't had any luck sighting Pluto with that telescope, however.
Dave Mitsky
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Chance favors the prepared mind.
De gustibus non est disputandum.
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JakeSaloranta
sage
Reged: 09/18/08
Posts: 234
Loc: Sisu, Sauna, Sibelius...
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3C 273 and Markarian 421 are both quite visible with 4.7" aperture. Same goes for the APM 08279+5255 in an 8" dob. Stellar objects are good targets for limiting magnitude and distance as long as you have dark skies and accurate enough maps.
3C 273 with a 3" refractor:
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 12222
Loc: Los Angeles
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Quote:
Deepest objects are always quasars, because they have maximal surface brightness (well, they are stellar !) and among the most luminous objects in the universe.
Here is a 15.2mag quasar in UMa at z=3.9, which translates to roughly 12 billion lyrs - should be feasible in a 14+ inch ... :-)
APM08279 0827+523 at coordinates 08 31 42 +52 45 18
I should try for that. I've gone past magnitude 17 with my 12.5" on stars, so that 15.2 shouldn't be too hard. I've seen the central star in M57, and though it, too, is magnitude 15.1-15.2, it's a lot harder than a stellar object that is not immersed in nebulosity.
Thanks for the suggestion.
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Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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I've seen a couple galaxy clusters around 3 billion light years away, maybe further with my 25". I was able to break the 2 billion light-year mark (barely) with my 18", again, with some Abell galaxy clusters. I've kinda always felt quasars were "cheating", but of course, that is not really true. Kudos to those that take the time to track them down with more devotion than I do. But the problem with quasars is, it doesn't take that big of a scope and you can see some most of the way back to the Big Bang. It makes it hard to talk about "how far can you see with that thing" if you're talking about quasars.
On the other hand, with the large galaxies in the centers of galaxy clusters, it's much more of a linear progression. My 18" seemed to bottom out at 2 billion light years, and my 25" seems to bottom out at 3 billion. I see it as more consistant and useful to talk about galaxies rather than erractic, gravitationally lensed, superluminous oddball quasars when talking about or considering how far a telescope can see. So when someone asks me "how far can you see with that thing?" I usually answer something like "I can see large galaxies about a quarter of the way back to the Big Bang".
Besides, to me, quasars are boring things that look like faint little stars. The double quasar and especially Einstein's cross can be kinda fun though. On the other hand, even galaxies 3 billion light years away are still clearly non-stellar, faint little fuzzies. If it's a faint fuzzy, I can more easily imagine I am peering a great distance that if I'm staring at a quasar that looks exactly like a very faint star.
Again, all these are just my views on the subject, and I make no claim that what I say is any more than just my opinion. I wish I could get the enjoyment out of quasars that other people do, but hey, I probably get more enjoyment out of very faint and distant galaxy clusters than those quasar-lovers would.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4115
Loc: Ireland
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While I do enjoy hunting down the odd quasar now and again, I'm mostly in agreement with John. I mean, which one of the following looks like more fun?
Mrk421; 360 million light years:
Abell1656 (Coma Cluster); 400 million light years:
Cheers,
-- Jeff.
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Tony Flanders
Post Laureate
Reged: 05/18/06
Posts: 3469
Loc: Cambridge, MA, USA
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Right. Quasars are fun because you know how far they are, but you have to take it all on faith because they *look* precisely like stars. To my taste, Coma Galaxy Cluster, some 400-500 million light-years distant, is the farthest object that's genuinely interesting through scopes in the 8-12 inch range. Bigger scopes bring in more distant (and even richer) galaxy clusters.
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Tony Flanders
First and foremost observing love: naked eye.
Second, binoculars.
Last but not least, telescopes.
And I sometimes dabble with cameras.
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PeterSurma
super member
Reged: 08/24/06
Posts: 122
Loc: Heidelberg, Germany
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Sure, of course QSOs are 'sort of boring', just like single stars are (well in fact these can be a thrill too, think of 'special' stars like certain variables, single stars in galaxies, crab pulsar, Barnard's star, Cygnus X-1, Campbell's Hydrogen Star...), I fully agree. Primarily, I wanted to point out that such objects by definition are the deepest thing you may ever see at a given mag limit.
Having said this, I still do find QSOs nice to have on my obs list because, you sometimes simply lack good skies. So with a 21.0mag/sas sky I simply will not try to reach out for faint clusters oder faint detail in galaxies. I'd rather take a (stellar-shaped) quasar and observe it, keeping in mind what it all means what I am seeing there...
Clusters and other objects with some detail are much more interesting to mee, too, sure ! However, I usually require excellent conditions (and preferably a really huge scope) for them to get really breathtaking...
Well anyway, excellent skies to all of you ! :-)
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Peter
Web: http://www.eyes4skies.de/home_EnglishVersion.htm
Scopes: From 3inch photographic APO to 20inch f/4 Dob
Edited by PeterSurma (10/14/09 09:13 AM)
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
So how far can an 8" typically see? How about an 11" or 14"? Or an 18" or 22" or whatever inch? Thanks people. This topic has always fascinated me.
Based on my experience with my own scopes, and extrapolating it downward to smaller apertures, I would THINK that you should be able to see the large, elliptical, core galaxies in dense galaxy clusters out to around 1 billion light years (maybe a little less) with an 8" scope, under very dark, transparent conditions, using a finder chart, and with experience of what to look for. Note: even if you meet all the conditions I just laid out, that does NOT mean that you will be able to see galaxies in EVERY galaxy cluster out to a billion light years, you'll only see some of the biggest ellipticals, and not all galaxy clusters have these.
An example of a galaxy at one billion light years that I would THINK should be visible in an 8" would be IC 1101 in ACO 2029. According to wikipedia, it's 5-6 MILLION light years across. That sounds really, really big, so let's check it. Measuring IC 1101's angular diameter with the ruler tool in SIMBAD, it's a little over 1.3' across. That's ((1.3/60)/360)*2*pi = 0.00038 radians. Using the small angle approximation, that means its diameter is 0.00038*1e9 = 380,000 light years. So wikipedia fails again. Regardless, it's still a huge galaxy.
Edited by tatarjj (10/14/09 02:48 PM)
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nytecam
Postmaster
Reged: 08/20/05
Posts: 5751
Loc: London UK
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Quote:
PS: I should mention those are all visual. I think Nytecam has taken pictures of APM08279+5255 with an 70mm ETX.
Thanks Jeff  My 70mm aperture shot of above [as 1 deg square finder chart for visual scopes  ] here and my video clip on quasar observing here.
Good quasar viewing - a journey of the mind 
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Nytecam 51N 0.1W
Meade 30cm LX200+ETX-70+e-finder+C8+Ha+CaK PSTs SBIG SGS+homebuilt spectrographs
Starlight SXVF_M9+Lodestar CCDs/Canon 300D DSLR/Fuji E550
My observatory build-ETX-70 imaging-my videos
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Edwin Quiroga
professor emeritus
Reged: 01/31/08
Posts: 612
Loc: Miranda, Venezuela
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With my 85mm scope I have seen the G1 Cluster, AKA Mayall II (magnitude 13.7, 2.9 million light years) from a dark site. I saw it as an obvious non-stelar object. Accoding the literature, a 85m scope has a reach of about magnitude 12-12.5. I was encouraged to find out G1 for the report of a 60mm Scope Club member who saw G1 with his Telementor (63mm).
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TeleVue 85 w/FeatherTouch
Televue Panoptic 35
Pentax XW (3.5, 5, 7, 10, 14, 20)
Pentax XO 2.58
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JakeSaloranta
sage
Reged: 09/18/08
Posts: 234
Loc: Sisu, Sauna, Sibelius...
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Quote:
Accoding the literature, a 85m scope has a reach of about magnitude 12-12.5.
For example, probability of detection with 3" (76mm) telescope:
98% chance to detect a 12.1 magnitude star
90% chance to detect a 12.6 magnitude star
50% chance to detect a 13.1 magnitude star
10% chance to detect a 14.1 magnitude star
5% chance to detect a 14.8 magnitude star
2% chance to detect a 15.6 magnitude star
http://www.twcac.org/onlinehorizon/eyepiecedarkly.htm
http://www.go.ednet.ns.ca/~larry/astro/maglimit.html
/Jake
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Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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Great sites Jake! Those will be a big help to me in deciding what is on my grand list of targets.
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Celestron CPC 1100
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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Edwin Quiroga
professor emeritus
Reged: 01/31/08
Posts: 612
Loc: Miranda, Venezuela
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Really an useful article indeed!
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Jim Curry
sage
Reged: 10/29/07
Posts: 432
Loc: Maine
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From the article >The long observation time sort of allows your eyes to accumulate light like film<
I don't believe that's an accurate characterization of your eye's functioning. Chemical changes improve dark adaption but I've never heard of "accumulating" photons in your eye/brain system.
Jim
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Vixen 140 refractor
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