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72 Pegasi

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#1 mikey cee

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Posted 07 November 2012 - 01:46 AM

Several nights ago I easily split 72 Pegasi. The Burnhams handbook states a seperation of only .5 sec. I observed the star high overhead near the meridian. My Istar 10" f/11 R30 handled it quite easily at 625x and 815x. The clean black void between the componets was estimated to be just as wide as the airy discs were in diameter!! I can't recall the exact specs on an aperture of this level but believe it to be about .465 arc sec. I'm hopefull that the new Raycorrs will allow a "cleaner" split although I'm sure that less than perfect seeing conditions were fighting me that night. Jupiter was high in the east about half way to the meridian also. So I rolled over to it and was tongue tied....something of a rarity for me IMOH. Even with a Moon and cirrus in the sky Jupiter shown brightly. I have seen skies much better than tonight and I can't contain my eagerness. Istar's lens is really living up to it's "hype" which is a pleasant experience. ;) Mike

#2 Rich (RLTYS)

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Posted 07 November 2012 - 06:44 AM

Congratulations on a sucessful observation.

Rich (RLTYS)

#3 7331Peg

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Posted 07 November 2012 - 02:43 PM

Looks like the current separation is .57" -- pretty darn good shooting! Here's a link to the latest orbital information: 2012 Separation and PA


John :refractor:

#4 azure1961p

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Posted 07 November 2012 - 07:35 PM

Most Ive gotten with the 8 was a Dawes Notch or in lesser seeing, a wasp waist - no surprise there given the .576 Dawes Limit for that aperture. It IS a nice one.

Pete

#5 mikey cee

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Posted 13 November 2012 - 07:06 PM

Anyone else out there attempting this nice yellow duo?? It's as close to the zenith double around. I'm using it to check the nightly conditions before going to Uranus and Jupiter! ;) Mike

#6 Asbytec

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Posted 13 November 2012 - 10:44 PM

That's far below the Sparrow limit for my scope. Man, that's pretty sweet using a tight double to check seeing. I've done that with 31 Tau at the Dawes limit, too. Jupiter's been rocking this season. What can you make on Uranus?

#7 azure1961p

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Posted 13 November 2012 - 11:20 PM

norme id bet you'd get a certain elongation though.

pete

#8 Asbytec

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Posted 14 November 2012 - 12:04 AM

There you go, Pete, pushing me to push myself, again. Your challenges keep getting tougher. First, Plato craterlets. That was easy compared to Enceladus. Enceladus is harder than Ganymede, though. Now this would be tougher than all other's combined. :)

Well, it would take some perfect seeing a maybe some "stupid" magnification. Sparrow is 0.71" in a 6", this one is at 0.45" arc. Theoretically there may be some elongation since they are not exactly on top of one another. But, the spurious disc probably covers up any elongation.

#9 WRAK

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Posted 14 November 2012 - 10:37 AM

... The clean black void between the componets was estimated to be just as wide as the airy discs were in diameter!! ... Mike


Envy scope and especially the clear sky. Just another optical wonder - the Airy disk radius should be somewhat above 0.5 arc sec and to get here black space in this size would require the spurious disk radius being less than 33% of the Airy disk radius. Impossible with this bright components I would think - a clear 8 should be all you can get here with 10" aperture. Envy remains.
Wilfried

#10 mikey cee

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Posted 14 November 2012 - 11:06 AM

Norme I've only had one night so far where Uranus defines a sharp limb. Unless you have a bunch of nights like this it's going to be hard to look for any "banding" as some claim they have seen. I have only caught one or two moons on past nights. But the sky glow here in the metro area is giving me a run for the money tho'. In dark skies I have no doubt I could see 4 moons. Jupiter looks like a processed stacked image minus the vibrant colors. Hopefully some of that may change If Istar ever gets their Raycorr off the drawing board. I love double stars a lot. Just the other night I found Arietis 10 very nice. ;) Mike

#11 Asbytec

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Posted 14 November 2012 - 11:18 AM

Mike, sure. I probably should not have mentioned Uranus, it's been contentious. But, curious none the less. I would think a 10" refractor might stand a snowball's chance if any scope might.

Anyway, you have quite the double star set up, Mike. Next time someone asks which scope is best for doubles (or anything else), mind if I mention yours? :)

Jupiter, to me, looks like just a few stacked images. Raw. :)

Congrats on Arietis 10, never heard of it. Probably out of my scope's league. So, what's your draw to doubles, color or separation, or both? I guess I like the challenge of close doubles, but there is no arguing the beauty of colored ones, either.

#12 azure1961p

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Posted 14 November 2012 - 07:13 PM

I'm going to put a blurb in for Thomas -astro-jensen...

If I recall correctly he elongated doubles with an 80mm refractor (or there abouts) down to 0.5" . If I'm off its not by much. all that to say you can probably elongate 72. Aberrator leads me to believe something as low as 0.2 with the peculiarity being in the diffraction rings seen first. something about the elongated rings pop before its more easily seen in tge disc. That's sim. In practice I've seen a few Dawes and sub dawes but never attempted a value half that.

jus throwing it out there.

pete

#13 Asbytec

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Posted 14 November 2012 - 09:23 PM

It does sound possible, Pete, to get some elongation down to about .5" arc. The Sparrow limit says there will be zero contrast transfer between the spurious discs as seen in a scope of a given aperture and Airy disc radius.

This implies the spurious discs are nearly on top of one another. If memory serves, Dawes limit was not tough to "split" with a definite peanut shape in great seeing. Reducing that by a few 10ths of an arc second (from 116/d to 107/d) should make little difference in the elongation observed. Much below that becomes another problem all together.

Intuitively there should be some elongation at any separation, it just get's progressively harder to observe. Maybe the fainter the better. But, with 6th mag pair at 0.5", one might imagine the brighter spurious discs will overwhelm each other being that close. In theory, but maybe not in practice.

#14 mikey cee

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Posted 14 November 2012 - 10:46 PM

Norme separation more than colors. I like different contrasting magnitudes also like Arietis 10 for example. Yes by all means you can cite my scope and observations with it whenever. ;) Mike

#15 Asbytec

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Posted 15 November 2012 - 04:16 AM

:)

Might give 72 Pegasi a look tonight. Pete's got me curious about the possibility of elongation. Dang him...he always does that to me. :)

#16 Asbytec

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Posted 15 November 2012 - 11:31 AM

Okay, 72 Pegasi, eh? Its an orange star about 5th mag, according to Stellarium, and sits at the apex of a flat V shaped asterism.

At 313x and 384x, the diffraction pattern was slightly oval oriented basically east west. The spurious disc did appear elongated with a brighter component west and a dimmer component comprising the trailing edge (as the star drifted through the FOV.) I estimate elongation (PA) to be about 100 degrees +/- 10 degrees. No peanut shape, just an elongated spurious disc.

So, if I observed it correctly, the companion is somewhat dimmer with a PA ~ 100. Is that correct? (I have not checked it's stats, just putting up observation for scrutiny.)

Now, I did slew to 64 Peg to verify if the atmosphere was causing some distortion. However, 64 Peg, just west of 72 Peg, was a clearly white and round spurious disc with a faint circular diffraction ring. Its the same magnitude as 72 Peg.

Well, if that description is accurate (enough) I might have seen elongation. I really think I did, it wasn't too terribly difficult or nearly impossible, but it was not easy.

15 Nov 2012, 1500UT seeing 8/10, transparency mag 5.

Edit: Okay, just checked the PA at 070. Maybe I made a mistake, but it appeared to be just south of 90 degrees. Right? Or at least trailing almost directly behind, but just off a line drawn directly east and west at 90 degrees PA. So I added 10 degrees and guessed at it. Did I do the math right?

Edit, again: No, I read the data wrong: :foreheadslap:

2012 Theta = 102 and Rho = 0.566.
That was it! Wow, closest double I have observed (without splitting it.)
:jump:

Edit: Sketch added. The image scale is enlarged to better show the very small details.

Attached Files



#17 mikey cee

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Posted 15 November 2012 - 05:47 PM

Norme.....you nailed it. In my refractor tho' with a diagonal and binos the primary leads to my left in the eyepiece and the secondary trails. I've never taken time to really do a position angle but they indeed are close to an E-W appearance. I get a kick out of the diffraction rings. They appear as large dim peanuts with airy discs cleanly seperated nestled just inside.....neato to surreal! I hope to get lucky and hit a better night if that is possible around these parts. They are few and far between...you just have to be lucky. :grin: Mike

#18 Asbytec

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Posted 15 November 2012 - 08:18 PM

Thank you, Mike, 72 Peg turned out to be quite exciting. Thanks for the report above, and Pete's bold claims one could do it.

52 Ori has the same appeal to me, not as tight but more like a diamond ring. 31 Tau was a test double at the Dawes limit. Viewing it was a milestone. Yes, seeing here is usually upwards of 8 or better during the dry season. Very fortunate. :)

Anyone else out there attempting this nice yellow duo??


Me. :jump:

#19 Asbytec

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Posted 16 November 2012 - 03:49 AM

Sketch added above. Nice double, Mike. Thanks.

#20 Astrodj

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Posted 17 November 2012 - 08:19 PM

I had better than usual seeing last night so I gave this one a try after seeing it in the forums.

I tried powers up from 300X-750X in my 10" dob, and couldn't confirm a split of any kind. There were times when I thought maybe for a fleeting second or two, but it was probably an artifact of the seeing.

It was fun trying though.

#21 Asbytec

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Posted 17 November 2012 - 09:03 PM

DJ, rather than a Raleigh or Dawes split, did you notice some elongation? I'd urge you to keep at it. :)

#22 Astrodj

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Posted 18 November 2012 - 01:37 AM

I can't say that I saw anything other than one star with any certainty. The image just wasn't steady enough for a sub-arc second double, indeed, half an arc second at that.

I will try again if I get an uncommonly good night, though!

#23 Asbytec

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Posted 18 November 2012 - 02:24 AM

Ah, yea, guess the seeing really has to cooperate. I wish you luck on it in the future.

#24 Javier

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Posted 18 November 2012 - 08:35 AM

If the clouds hold out I'm going to try for it again this evening. I've had two clear nights in a row but the seeing has been a mess. A .5" double is rather difficult for my area but I have to give it one more shot.

#25 azure1961p

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Posted 18 November 2012 - 05:21 PM

Dang it you nailed that color good.

Pete






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