Buddy


Posted 07 May 2010 - 10:02 PM
Posted 07 May 2010 - 11:54 PM
Wow, I just found a picture at the bottom of the forum that had the magnitude of stars around M57. I was looking at M57 last night with my 10" Dob at 300x. If that picture is correct, well then I could see stars to mag 15.6 with averted vision. Could this be true? I also thought that I saw the central star a couple of times with averted vision. I could not hold the central star but for maybe 40% of the time. I did not think this was possible with a 10" reflector. You tell me, was it averted imagination or do you think I may have seen it?
Buddy![]()
Posted 08 May 2010 - 03:48 AM
I was looking at M57 last night with my 10" Dob at 300x. If that picture is correct, well then I could see stars to mag 15.6 with averted vision. Could this be true?
I also thought that I saw the central star a couple of times with averted vision. I could not hold the central star but for maybe 40% of the time. I did not think this was possible with a 10" reflector. You tell me, was it averted imagination or do you think I may have seen it?
Posted 08 May 2010 - 08:43 AM
Posted 08 May 2010 - 09:27 AM
Posted 08 May 2010 - 10:29 AM
Wow, I just found a picture at the bottom of the forum that had the magnitude of stars around M57. I was looking at M57 last night with my 10" Dob at 300x. If that picture is correct, well then I could see stars to mag 15.6 with averted vision. Could this be true? I also thought that I saw the central star a couple of times with averted vision. I could not hold the central star but for maybe 40% of the time. I did not think this was possible with a 10" reflector. You tell me, was it averted imagination or do you think I may have seen it?
Buddy![]()
Posted 08 May 2010 - 11:02 AM
IC1296 is usually visible in my 12.5" under mag.21.4 skies.Hi Buddy,
Under excellent dark skies, a 10 inch aperture is definitely capable of revealing mid-15th magnitude stars. It's not trivial--not by any stretch--to go that deep but is most definitely doable. Here's a link to observations of this field I've made with 10 and 18 inch telescopes: M57 Central Star Observations.
The central star was detected with averted vision in my old 10 inch, f/4.5 Meade Starfinder. It's a fairly easy direct vision object in my 18 inch Obsession. But getting back to observations with moderate apertures, I find the trio of 14.7 to 15.7 magnitude stars pointing towards the western edge of M57 to be a good measure of conditions for the detection of the 15.2 magnitude central star. If the 15.7 magnitude star at the apex of this right triangle asterism can be seen, the central star also stands a good chance of being detected. Though half a magnitude brighter, the central star resides amidst the delicate nebulosity filling the ring. And this makes the central star a more challenging target.
The 15.6 magnitude star you reference also serves as a good indicator. Seeing this star should encourage one to go for the central star. And if you detect the central star, give nearby IC 1296 a go. I've only seen this in my 18 inch but there are reliable reports made with smaller apertures.
Bill in Flag
Posted 08 May 2010 - 12:30 PM
It's good to push the limits, huh?
Posted 08 May 2010 - 04:06 PM
Posted 09 May 2010 - 09:14 PM
Posted 11 May 2010 - 04:46 AM
Posted 11 May 2010 - 11:13 PM
Posted 11 May 2010 - 11:42 PM
The limiting magnitude for an 8" scope is 15.2, so seeing a half magnitude fainter must have been difficult, but obviously not impossible. The limiting magnitude for a 12" is 16.1, which could allow you to see that same 16.6 magnitude star in slightly better skies, but that 16.6 magnitude point of light is quite a stretch even for a 16" scope. I've seen the central star in my 12" scope, and it's far more difficult then that slightly fainter 15.7 magnitude star, and nearly impossible if the conditions are not perfect...clear skies...
Posted 12 May 2010 - 12:14 AM
The limiting magnitude for an 8" scope is 15.2, so seeing a half magnitude fainter must have been difficult, but obviously not impossible. The limiting magnitude for a 12" is 16.1, which could allow you to see that same 16.6 magnitude star in slightly better skies, but that 16.6 magnitude point of light is quite a stretch even for a 16" scope. I've seen the central star in my 12" scope, and it's far more difficult then that slightly fainter 15.7 magnitude star, and nearly impossible if the conditions are not perfect...clear skies...
I am guessing that this was a typo, because I said that I was using my 10 inch Dob, not an 8 inch. The star that I observed, which is shown on David's photo above, is magnitude 15.6, not 16.6 . Just trying to not lead anyone astray with what I saw. You are correct, this was a difficult observation, of sorts. Note that I said that the central star was only seen with averted vision and only for a portion of the time. This star came in and out of view as the seeing varried.
Thanks,
Buddy
Posted 12 May 2010 - 01:11 AM
Posted 12 May 2010 - 04:27 AM
The limiting magnitude for an 8" scope is 15.2, so seeing a half magnitude fainter must have been difficult, but obviously not impossible.
Posted 12 May 2010 - 11:11 AM
Posted 12 May 2010 - 12:58 PM
That does not count for the probability of detection of the human eye. The chance of detecting a 15.2 magnitude star with an 8 inch telescope is 50% and a 16.2 magnitude star is 10%. Then there's of course the way you're observing. If you're really trying the limiting magnitude of your telescope - you probably can go deeper than just looking for a faintest star in your sketch or something similar.
Posted 12 May 2010 - 01:12 PM
One can't even say this much with any certainty. Some people will *never* see much past 14.7 in an 8 inch, while others may creep a little past 15th magnitude at the 50% observation level (i.e. the star is visible about half the time you are looking for it, which is what that percentage actually means). There is just no way to assign an absolute limit (even with probabilities).
Posted 13 May 2010 - 06:53 PM
Posted 14 May 2010 - 12:52 AM
I havent had the privledge, though miracle is a better descrition of M57 central star through my 8" reflector. I am pleased to see however that with just a little more diameter, " a lot" of folks seem to pick it.
Most know this, but for those who arent familiar with the onslaught of doubt, be forwarned: folks who have seen M57 withg HUGE optics [40" comes to mind} have NOT been able to make the central star. As a result , some are bitterly adamant that based on that, all those who claim to see it in medium apertures are over using there imagination.
I think the meart and potatoes here is that you need a scope that is large enough to "bring it in" but one also that is capable of atleast producing a reseanably crisp and proper stellar image. Large medium apertures seem adept at hitting this zone while gargantuan optics perhaps are so compromised by the seeing distroting stars way way beyond what could be called a "proper" diffraction poattern that there star, however much brighter is litarally blended away into the gauzzie grey of the Nebulas delicate central regions.
My hats off to all of you on this stellar "trophy". LOL, just be prepared for doubting observers. Its a tough crowd!!
Pete
David, hope all has been well.
Posted 15 May 2010 - 04:57 AM
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