Where can I find the largest known galaxy, IC 1101? I am aware of the location o the Abell 2029 cluster, but I just don't know where to find the aforementioned galaxy. How about Malin 1? Am I, by any chance, going to be able to see them with an Orion XT8, and a plossl 9mm eyepiece?

A question on large galaxies.
#1
Posted 12 September 2016 - 08:25 AM
#2
Posted 12 September 2016 - 08:48 AM
Hi Matuchkin,
If I remember, IC 1101 is a pretty high magnitude (14 or 15, something like that) so I'm not sure it will be visible through many amateur level telescopes. Definitely not through a 9 mm eyepiece. The trick with the deep sky objects, or "faint fuzzies" is not magnification, it's light gathering and a nice wide field of view. I hope this helps.
Eric
#3
Posted 12 September 2016 - 09:20 AM
G'Morning. IC1101 is pretty much dead center in Abell 2029. Guide 9 says it's 14th magnitude, but the IC catalog has it at 15. It's about 1.2 by 0.6 arc minutes, but that includes some of its outer regions. So look for a faint, stretched out, Jupiter-sized glow. I don't think it's hopeless in an 8-inch 'scope if your skies are really excellent and your eyes fully adapted. I think magnification will be your friend, so the 9mm sounds like a good choice to me. But it's going to be a tough target.
Here's a finder chart with stars down to around 14th magntiude. The red circle is 1/2 degree in diameter. As you know, the cluster is a short hop 4 degrees NW from M5, about 1 degree NW from 5th magnitude 3 Serpens.
Happy hunting!
dc
#4
Posted 12 September 2016 - 09:43 AM
Hi Matuchkin,
If I remember, IC 1101 is a pretty high magnitude (14 or 15, something like that) so I'm not sure it will be visible through many amateur level telescopes. Definitely not through a 9 mm eyepiece. The trick with the deep sky objects, or "faint fuzzies" is not magnification, it's light gathering and a nice wide field of view. I hope this helps.
Eric
The trick with deep-sky objects lies precisely in the magnification, in that it needs to be matched to suit the telescope, the object and how our eyes react to dim light. A 9mm eyepiece would NOT be a stupid choice in trying to detect faint galaxies with an 8" f/6 telescope, in that it would produce a 1.5mm exit pupil, which is almost right in the goldilock's zone between nice, dark backgrounds and not overmagnifying dim stuff, and decent image scale, which is critically important to seeing faint, small galaxies. One of my most used eyepieces on my 12" f/5 dobsonian is a 9mm ES100 and I use it a lot to detect faint, small objects. It reveals far dimmer galaxies than, say, my 30mm ES82.
Light gathering is of course important, but you need to use what you've got. A wide field comes quite low on the list of important things for detecting faint galaxies. In fact, one of the best observers I know, use orthoscopics on his giant dobsonian, whenever he tries to see ultrafaint objects.
Clear skies!
Thomas, Denmark
#5
Posted 12 September 2016 - 10:06 AM
Hi Everyone!
Thanks for the corrections! I have an 11inch Schmidt Cassegrain and for the most part, if I'm looking at faint fuzzies, my 9mm is TOO much. I find my 13mm to 17mm works the best. I imagine the seeing would have to be REALLY good to pull into 14-15 magnitudes though, even for an 8 inch dob?
Eric
#6
Posted 12 September 2016 - 11:19 AM
What if I, say, press a camera to the eyepiece and raise the exposure? What will that look like?
#7
Posted 12 September 2016 - 11:29 AM
I completely agree on the use of orthoscopics for the faint fuzzies. Alvin Huey is a well noted observer of hard to view faint galaxies, planetary nebulae and other "fuzzies". He is also the author of some really good observing guides that you get for free on his website. He is a real proponent of orthoscopics. Here is a link to Alvin's website: http://www.faintfuzzies.com/ . From the home page click on the link titled "Observing Tips" for what Alvin has to say about the wonderfully simple orthoscopic eyepiece.
I believe after reading what Alvin has to say about what eyepieces he personally likes to use for the fuzzies it can be a good learning experience. He has some very good comparisons of eyepieces that he uses to observe with.
What Thomas says is true! It's all about finding the right exit pupil and magnification for your particular telescope. There is an eyepiece that produces the best magnification and dark sky background. It's all about producing the best contrast. For a 8" f/6 Newt it will somewhat different than a 11" f/10 SCT. My 20" f/5 has yet another sweet spot.
Good luck Matuchkin. Looks like you've caught the fever. Next thing you know you'll be rating them by how far away they are, not by how big they are. 310 MLY for me, but I still have yet to get the big beast out to a nice dark site.
#8
Posted 12 September 2016 - 12:49 PM
Hi Everyone!
Thanks for the corrections!
I have an 11inch Schmidt Cassegrain and for the most part, if I'm looking at faint fuzzies, my 9mm is TOO much. I find my 13mm to 17mm works the best. I imagine the seeing would have to be REALLY good to pull into 14-15 magnitudes though, even for an 8 inch dob?
Eric
Hi Eric
A 15mm eyepiece on an f/10 SCT delivers exactly the same exit pupil as a 9mm on an f/6 dob, so you indirectly came to exactly the same conclusion I did, namely that a 1.5mm exit pupil is close to the "goldilock's zone" for most faint objects.
Observing mag 14 - 15 objects with an 8" should not at all be ruled out, if they have high surface brightness, but it's going to be quite a challenge at mag 15. Dark skies are a must.
Clear skies!
Thomas, Denmark
#9
Posted 12 September 2016 - 01:51 PM
The small size of this galaxy means the magnitude 14.7 of total integrated magnitude translates to a magnitude 14.1 on surface brightness,
the same as the average on M33.
It's small size will make it less visible at first, though it might pop in and out as you pin down the location.
I would advise a finder chart so you know exactly where it should be--that will aid identification.
And it will be exceedingly difficult in an 8" scope unless you are using the scope
in skies of, say, NELM 6.8 and darker.
Malin 1 is exceedingly small--the size of many small PK planetaries, and also exceedingly faint (m.15.8).
I've tried a half dozen times on this one over the last 12 years with a 12.5" at dark sites, and never been able to see it.
I strongly doubt its visibility in an 8". I've never seen a galaxy at a distance of 1 billion light years, and the smallest instrument I've heard of
that could was about 18".
#10
Posted 12 September 2016 - 03:22 PM
Billion light years yes, but a very huge galaxy. 100x as wide as the milky way. Thicker should mean higher surface brightness.
#11
Posted 12 September 2016 - 04:46 PM
This one, though, has an exceedingly LOW surface brightness.
Ellipticals and edge-on spirals are easier to detect at great distances.
#12
Posted 14 September 2016 - 08:18 PM
IC-1101 is on the border between Virgo and Serpens, which makes it very difficult at best because it has a magnitude of 15 and an apparent size of more than one arc-minute. The fact the window of opportunity to see it this year is closing soon as well. If you want to try for it, you will have to start looking for it as soon as full darkness falls. Otherwise, wait until next spring and summer when it's better placed for observation. It won't hurt to bring a 16-inch to bear on this one too, to see it with an 8-inch would require very dark and clear skies. It won't be an easy object for a telescope with twice the aperture given that its surface brightness is 23.1 Mag/arcsec2. If you do succeed in finding it, you'll be looking at a galaxy that is one billion light years away from us.
Taras
Edited by Achernar, 14 September 2016 - 08:30 PM.
#13
Posted 14 September 2016 - 10:27 PM
The Wikisky image seems to show a core that will appear fuzzy stellar in smaller scopes and the galaxy as a whole looks brighter than the 14.7 quoted in various places. The gradient from core to outside edge looks fairly steep. Checking NED the visual mag is given as 13.2 which looks about right to me.
Galaxies tend to be tougher to see than stellar objects of the same magnitude even in dark skies. This one is likely to be challenging in an 8" even in dark skies at 13.2, but if the sky is truly dark and the galaxy is well positioned it should be in range.
#14
Posted 14 September 2016 - 11:14 PM
The fact the window of opportunity to see it this year is closing soon as well.
Yep.
And a location in your profile helps let us know where in the sky your window of opportunity is.
#15
Posted 15 September 2016 - 10:40 AM
The fact the window of opportunity to see it this year is closing soon as well.
Yep.
And a location in your profile helps let us know where in the sky your window of opportunity is.
From where I am, I would say it's already too late this year to look for it because it will be swamped by light pollution.
Taras
#16
Posted 15 September 2016 - 11:35 AM
I mentioned the profile location info for the OP, but the same here at close to N 42° and W 93°.
By the time astronomical twilight ends, IC 1101 is only about 17° above the western horizon and deep into the Des Moines, Ankeny light pollution domes.
#17
Posted 15 September 2016 - 01:09 PM
Thanks for the corrections!
I have an 11inch Schmidt Cassegrain and for the most part, if I'm looking at faint fuzzies, my 9mm is TOO much. I find my 13mm to 17mm works the best. I imagine the seeing would have to be REALLY good to pull into 14-15 magnitudes though, even for an 8 inch dob?
the contradiction here is between magnification and exit pupil. the advice offered by thomas refers to the effect of magnification on visual contrast, and this is not really a function of magnification as an absolute quantity (for instance, 300x), but of magnification as a proportion of your aperture, which is one way to think of the exit pupil.
the basic relationship is that a larger aperture gathers more light, and this allows optimal viewing at higher magnification, since magnification, by expanding the visual extent of an object, dilutes the light it presents to the eye. an equivalent exit pupil simply means that increased magnification makes extended objects fainter in the same proportion that increased aperture makes them brighter.
there's great expertise on CN regarding magnification and exit pupil as separate topics, but not a routine care to distinguish when one or the other should be used (or even the misleading claim that exit pupil is equivalent to magnification).
this is where comparing eyepiece focal lengths can be confusing. your claim that 17mm works the best means, in the ƒ/10 optics of most commercial SCTs, you're operating at an exit pupil of 17/10 or 1.7 (that is, calculated the easy way, as eyepiece focal length divided by your telescope focal ratio). most observers find an exit pupil of about 2 is optimal for extended and nonstellar objects; stellar extended objects, such as globular clusters or galactic clusters, may not apply.
don answered well the practical issue of "can i see it in this scope?" i'd say both galaxies will not be visible in an 8" aperture, except possibly at an extraordinarily dark sky site. and because (as others have pointed out) the modern human aspiration is to burn ever greater quantities of coal to emit ever greater quantities of wasted illumination into ever greater expanses of warmer and warmer night sky, your chances of observing from one of those sites are diminishing rapidly.
excuse the digressions, but as the fisherman of galaxies might say, it all depends on your rod, your lure, and the stream where you go fishing. (scopes, eyepieces and dark sky sites in the metaphor.)
#18
Posted 15 September 2016 - 01:26 PM
but as the fisherman of galaxies might say, it all depends on your rod, your lure, and the stream where you go fishing.
I also use to say, that galaxies are like butterflies, (light)pollution kills them and so you must seek the most undisturbed, remote wilderness location to find the rarest, most beautiful ones. The analogy works with trout and other fish as well.
Clear skies!
Thomas, Denmark