Cotts
Just Wondering
   
Reged: 10/10/05
Loc: Toronto, Ontario
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Antares split! Plus some other nice ones...
#3165666 - 06/16/09 11:48 AM
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Last night I was working through some STF doubles with my new Intes M809 and for the first time since the scopes arrival in early May the seeing was superb; diffraction-limited for my 8-inch aperture. The temperature at 11pm was 12C and at 2am was 10C allowing the scope to reach thermal equilibrium with ease. I observed all the STF's on Millennium Star Atlas charts 767 through 772 using my 17 Ethos (119x) and 8 Ethos (254x) most of the time with the 4mm Ortho (508x) on the very closest pairs to help me estimate the PA. The Gemini GoTo was used for target acquisition. (Sorry, purists)  When I saw perfect diffraction patterns I knew that I had a special night so I abandoned Mr. Struve and went for Antares and Nu Scorpii around midnight. They were still about an hour away from their maximum altitude here (about 20degrees for Antares....) but to my joy Antares yielded up his little friend at 254x. The view was steady, no 'waiting for that perfect moment' stuff tonight. Interestingly the companion was much harder to see at 508x, probably due to the fact that the seeing was not supported at such a high magnification - all I was doing was smearing the B-star. Once I knew where to look I was able to glimpse B with the 17 Ethos (119x) but only fleetingly. This was my third lifetime split of Antares and with the least aperture so far. Previously I split it with a 20" Obsession and my rather nice 10" Lightbridge. Buoyed by this success I then moved over to Mu Scorpii, the well-known and very difficult 'double-double' in NW Scorpio. Again the 8 Ethos at 254x was a winner. Bothe pairs were cleanly split. The separations are 2.4" amd 1.3" (WDS 2003 Obs.) 508x didn't help at all. I then thought that if the seeing were this good this close to the horizon how good must it be overhead? And Corona Borealis was directly overhead so it was off to try Eta and Gamma CrB. The seeing proved to be as near perfect as it ever gets here in the Great Lakes region and as good as a slightly above average night in the Florida Keys! Here are the data for these two challenge objects from the WDS's most recent 2004 observations (if someone has more up-to-date data please post it here..)
Gamma --- STF 1967 --- mags 4.04/5.60 - sep 0.7" - PA 114 Eta ----- STF 1937 --- mags 5.64/5.95 - sep 0.5" - PA 107
Gamma, despite being wider, was the more difficult pair because of the 1.5 magnitude difference and because, for my particular aperture, the b-component was on top of the first diffraction ring. At 254x I was unable, at first, to tease out the partner but the seeing allowed useful contributions from the 4mm at 508x. I could plainly see the companion on the first ring and there was dark space between the A/B pair. A definitive split!! Eta defeated me on a clean split, however. The B-component was much easier to see due to its being nearly equal to A. The best I could do was a deeply notched 'snowman' at 508x. The diffraction pattern was nearly motionless and not distorted in any way. Tonight, for the first time with this new scope, I was able to confirm for myself the claimed 1/9 wave, 95.7 Strehl which are claimed on the certificate which came with the scope. Thanks to Mark at Teton! And thanks to Mr. Nagler whose Ethos eyepieces are fully capable of this sort of high-res work. Not a bad night's work, really. Dave, observing at Castleton, Ontario.
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Clive Gibbons
Mostly Harmless
   
Reged: 05/26/05
Loc: Oort Cloud
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Re: Antares split! Plus some other nice ones...
[Re: Cotts]
#3165714 - 06/16/09 12:26 PM
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Good hunting there, David! 
I was out observing a bit farther to the southwest from you and also noted the seeing was better than it had been in quite a while. It makes a nice change.... wish it would happen more often.
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Bonco
Post Laureate
   
Reged: 04/17/06
Loc: Florida
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Re: Antares split! Plus some other nice ones...
[Re: Clive Gibbons]
#3166659 - 06/16/09 09:43 PM
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Nice report.
During really good seeing here in Florida I've split Antares with my 3 inch. I've often viewed it with my 4 inch f/5.
It's one of my favorite doubles. Good job getting a split from Canada.
Cheers, Bill
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leexeen
scholastic sledgehammer
Reged: 08/08/07
Loc: Beijing, China
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Re: Antares split! Plus some other nice ones...
[Re: Bonco]
#3166702 - 06/16/09 10:06 PM
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It is really impressing to hear the split of Antares at such a high lattitude area. This really gives me confidence to try it next time. I had almost given up because I failed many times due to the bad seeing and its low position in the sky.
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proud uncle
Carpal Tunnel
   
Reged: 01/22/07
Loc: Central Texas
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Re: Antares split! First time for me.
[Re: Cotts]
#3167653 - 06/17/09 12:00 PM
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I had my first split of Antares last night. Seeing Antoniadi III; NELM = 4. At 208x (6mm Planetary), after a couple minutes at the eyepiece, it popped into view, appeared a very light green or blue, almost white, with a very narrow but steady black space between. My estimated PA was 285d (primary nearly following the secondary as they drifted across my fov). As Antares A was getting fuzzy at that power, I lowered the power to 150x. No split detected, though I detected an elongation at the previously observed PA. Increasing the power to 200x (12.5mm Plossl barlowed), there was the companion again; I think that time it appeared slightly crisper and somewhat more white, but not sure.
Cotts, what PA did you estimate? Does anyone know the WDSC most recent PA, sep., and specral class info? I tried searching the WDSC, but I am a total newb at using it, and couldn't find Antares. My approximate coordinates for Antares are 16h30m, -26 deg.
There have been one or two times I thought I detected it's presence, but was not certain. This time, because of the steady black space, I'm convinced I found it. I had tried several time over the past three years. Last night was my first attempt this year.
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Cotts
Just Wondering
   
Reged: 10/10/05
Loc: Toronto, Ontario
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Re: Antares split! First time for me.
[Re: proud uncle]
#3168069 - 06/17/09 03:44 PM
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Hi, Kenneth. The PA of Antares has been in the 270 - 275 range for many years. The apparent orbit is nearly edge on to us so Antares B appears around 270 or around 90 degrees. The separation varies from nearly 0 to about 2.8". Since the period of the orbit is several hundred years we mere mortals can expect the Antares system to be identical for the rest of our existence and then some. Perhaps in the year 2525 (obscure pop culture reference....) a couple of CN'ers will discuss the appearance of Antares B at 90 degrees PA with a separation of about 2.5".
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proud uncle
Carpal Tunnel
   
Reged: 01/22/07
Loc: Central Texas
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Re: Antares split! First time for me.
[Re: Cotts]
#3168151 - 06/17/09 04:17 PM
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Thanks, David. So, my PA estimate of 285 degrees is close. Do you know approximate current separation? What about spectral classes? Judging from the different colors, I would assume very different spectral classes. How do the absolute magnitudes compare?
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Clive Gibbons
Mostly Harmless
   
Reged: 05/26/05
Loc: Oort Cloud
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Re: Antares split! First time for me.
[Re: proud uncle]
#3168446 - 06/17/09 07:08 PM
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Antares at Wiki.
FWIW, Dibon-Smith lists the sep. as 2.6 arc sec.
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FUNA
member
Reged: 05/04/09
Loc: hitachi-city Japan
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Re: Antares split! Plus some other nice ones...
[Re: leexeen]
#3171045 - 06/19/09 07:08 AM
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Altitude of Antares at the culmination is very important fctor for watching Antares companion. But,Antares is difficult double star.
Accoding to Australian astronomy magazine:SKY&SPACE;JUN/JUL2000;
"Antares is a tricky double;Antares itelf is a celebrated double star,although it is a very difficult one. The companion is of magnitude 5 and is only three arcseconds away. It's not a beginner's object. you'll need a moderate aperture and a very steady night."
I think that difficulties of Antares companion's resolution by small apeatrue telescope as follows;
(1)Small separation and large difference of magnitudes between primary and secondary stars.
(2)size of red star's Airy disk is larger than blue star's Airy disk (difference is about10%).
What is minimum apeatrue to watch Antares companion?
I have read somewhere that someone reported he cuold watch Antares companion by Nikon 8cm refractor. Also some Japanese amature reported he cuold watch Antares companion at 6cm refractor(in this case, 6cm means that it step down of 15cm refractor). In any case,as far as I know, 6cm refracor is minimum apeature to watch Antares companion.
Kazumi
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instruments:
Zeiss APQ100/640 with Zeiss TM german equatorial
Zeiss eyepieces(A-4,A-25,W-31S,
10mm Monocentric Okular(JENA))
Van Slyke's Bifilar micrometer
LOMO EFM-16x eypiece micrometer
Zeiss 10x40B
Edited by FUNA (06/19/09 07:12 AM)
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Clive Gibbons
Mostly Harmless
   
Reged: 05/26/05
Loc: Oort Cloud
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Re: Antares split! Plus some other nice ones...
[Re: FUNA]
#3171150 - 06/19/09 08:53 AM
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Back in 2002, I was able to see the companion of Antares using a Takahashi FS-78 refractor at magnifications of 232x and 154x. It was most easily seen at 232x. Seeing was excellent at the time. This was at north latitude 43.5 degrees. It's rare in this area to have such steady air.
Last August, I spotted the companion once again, this time with a 110mm ED refractor stopped down to 90mm and also using the scope at it's full aperture. Magnification was in the 200x range (sorry, don't remember the exact number). Again, very steady air. Unfortunately, the very good seeing didn't last for more than an hour.
Based on my experiences, it seems that excellent seeing is a most important factor for spotting the companion in a small telescope.
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exile
sage
Reged: 01/15/08
Loc: Guangzhou, China
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Re: Antares split! Plus some other nice ones...
[Re: Clive Gibbons]
#3171744 - 06/19/09 03:14 PM
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I split this in morning twilight during a brief spell of perfect seeing - also using an FS78 at 270x - last February. The companion lies almost exactly preceding (westwards) of the primary.
I think sharp optics and exceptional seeing are the go here. The little Tak could do it, but I'd never seen it before in an 8" or 12.5" Newtonian, despite many attempts..
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fred1871
sage
Reged: 03/22/09
Loc: Australia
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Re: Antares split! Plus some other nice ones...
[Re: Clive Gibbons]
#3172274 - 06/19/09 09:05 PM
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Quote:
Back in 2002, I was able to see the companion of Antares using a Takahashi FS-78 refractor at magnifications of 232x and 154x. It was most easily seen at 232x. Seeing was excellent at the time. This was at north latitude 43.5 degrees. It's rare in this area to have such steady air.
Last August, I spotted the companion once again, this time with a 110mm ED refractor stopped down to 90mm and also using the scope at it's full aperture. Magnification was in the 200x range (sorry, don't remember the exact number). Again, very steady air. Unfortunately, the very good seeing didn't last for more than an hour.
Based on my experiences, it seems that excellent seeing is a most important factor for spotting the companion in a small telescope.
I agree with Clive - good seeing is the essential. I've often failed to see Antares' companion with 8-inch and 10-inch 'scopes in mediocre seeing - and then found it visible with smaller apertures when the seeing was excellent. Living where Antares goes nearly overhead helps to give more opportunities. I'm at 35 degrees south latitude.
The smallest 'scope I've seen Antares' companion with was a 4-inch refractor, but I never tried with 'scopes smaller than that.
The best view I've ever had of Antares with companion was with a 7-inch AstroPhysics refractor at only 100x - a tiny greenish speck, very clear, beside the orange disk of Antares. That night Antares A was a disk, instead of the fuzzball that average seeing produces.
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Tamiji Homma
Carpal Tunnel
   
Reged: 02/24/07
Loc: California, USA
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Re: Antares split! Plus some other nice ones...
[Re: FUNA]
#3174295 - 06/21/09 09:36 AM
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Kazumi-san,
There are a few threads in the past.
Here is one from last year. Minimum Magnification to Split Antares
My minimum aperture to split Antares was with Vixen ED80SF f/7.5. I'll challenge Antares with 66mm this summer.
Tammy
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FUNA
member
Reged: 05/04/09
Loc: hitachi-city Japan
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Re: Antares split! Plus some other nice ones...
[Re: Tamiji Homma]
#3174364 - 06/21/09 10:32 AM
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Tammy-san,
Thank you very much for the past interesting threads.I hope your challenge is success. I think that minimum magnification to split is intersting theme for amature as well as minimum apeature to split. As shown in following my past watching report, Antares is not easy double star for me.
http://www2.odn.ne.jp/~ccr61210/www2.odn.ne.jp/antar99.html
Kazumi ------------------------ instruments: Zeiss APQ100/640 with Zeiss TM german equatorial Zeiss eyepieces(A-4,A-25,W-31S, 10mm Monocentric Okular(JENA)) Van Slyke's Bifilar micrometer LOMO EFM-16x eypiece micrometer Zeiss 10x40B
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leexeen
scholastic sledgehammer
Reged: 08/08/07
Loc: Beijing, China
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Re: Antares split! Plus some other nice ones...
[Re: FUNA]
#3174433 - 06/21/09 11:26 AM
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Thanks you, two kind sans! You bring very useful info for splitting Antares.
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Clive Gibbons
Mostly Harmless
   
Reged: 05/26/05
Loc: Oort Cloud
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Re: Antares split! Plus some other nice ones...
[Re: Clive Gibbons]
#3175986 - 06/22/09 09:48 AM
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Quote:
Last August, I spotted the companion once again, this time with a 110mm ED refractor stopped down to 90mm and also using the scope at it's full aperture. Magnification was in the 200x range (sorry, don't remember the exact number). Again, very steady air. Unfortunately, the very good seeing didn't last for more than an hour.
Just checked back to earlier notes and the magnification was actually 306x for last August's observation. Not 200x-ish.
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CESDewar
GorillAstronomer
   
Reged: 01/16/05
Loc: Blue Ridge, GA, USA
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Re: Antares split! Plus some other nice ones...
[Re: Clive Gibbons]
#3179402 - 06/24/09 01:20 AM
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Tonight the seeing was average but it was also very humid (85%RH) and mountain mists were rolling in and out, but I had no difficulty seeing Antares' companion in my TMB105/650 with a 2.5Nagler (260x) - appeared pale blue-green, but so would almost anything next to that blazing orange star!
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proud uncle
Carpal Tunnel
   
Reged: 01/22/07
Loc: Central Texas
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Re: Plus some other nice ones in CrB
[Re: Cotts]
#3179805 - 06/24/09 09:56 AM
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Corona Borealis was directly overhead so it was off to try Eta and Gamma CrB. The seeing proved to be as near perfect as it ever gets here . . . Here are the data for these two challenge objects from the WDS's most recent 2004 observations (if someone has more up-to-date data please post it here..)
Gamma --- STF 1967 --- mags 4.04/5.60 - sep 0.7" - PA 114 Eta ----- STF 1937 --- mags 5.64/5.95 - sep 0.5" - PA 107
Gamma, despite being wider, was the more difficult pair because of the 1.5 magnitude difference
This is similar to my experience last night. Seeing seemed to steadily improve. At the time I was observing in CBr, seeing was Antoniadi II. At 417x, Gamma's secondary appeared to occasionally "blink" into view. Eta, once I saw the split with definite black space, was steady. That sets a new personal record for the closest double I've split with my scope. I also tried for Theta, but no success.
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johnnyha
Postmaster
   
Reged: 11/12/06
Loc: Sherman Oaks, CA
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Re: Plus some other nice ones in CrB
[Re: proud uncle]
#3194420 - 07/02/09 03:37 AM
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Finally split Antares tonight! I've been dabbling in astronomy for years but just got interested in doubles the last few weeks and got the excellent Cambridge Double Star Atlas a few days ago. Tonight for the first time after just two weeks of trying almost every night, I split Antares cleanly with my NP101 at 308X from my backyard in Los Angeles. I also saw it split at 432x, this is with my 4x Powermate and 5mm Pentax XW, the blue-green disc of Antares' companion was clearly visible.
I suspected the split using my 3-6mm Nagler zoom at 3mm (180x).
What a great Atlas by the way I decided to look around Bootes tonight and with the help of the Cambridge Double Star Atlas I split and observed Izar, Zeta, Pi, Xi and Mu Boo. Also tonight split the double double in Lyra, Cor Caroli, Albireo, Mizar, and eta Cassiopeia. Can't wait for my 6" D&G F/12 which should get in around Xmas!
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