desertrefugee
professor emeritus
Reged: 08/06/07
Posts: 526
Loc: Arizona
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I've never been much of a binary observer, but admit that lately, I've become very interested in them. (It might have something to do with a recent move closer to Phoenix).
So, on a scale of 1 to 10, and considering the more mainstream doubles of separation greater than 1 arcsecond, how does Izar rank in difficulty of resolving the split? What with some difference in magnitude, color and, of course, the tight separation, I find it somewhat tough to split. Maybe my seeing has been somewhat substandard?
Thanks!
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"Look now upon the River of Heaven, Sky-Road of the Immortals, White with the star-frost of a billion years".
+++
-Darrell
Reflectors (114, 150, 254mm), Refractors (60, 76.2, 80, 120), MCT (125), way too many Binoculars
Cave Creek/Carefree, AZ
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starramus
Pooh-Bah
Reged: 09/01/04
Posts: 1124
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In poor seeing I split it easily with my 20" Obsession using a 9mm Televue Nagler yielding 282 power. I would say my instrumentation was overkill.  I just wanted to get a feel for the seeing.
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1978
Loc: Florida
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I have never had a problem viewing Izar with a 3 or 4 inch refractor. Actually I think it most interesting in smaller scopes that show pin point stars and colors that are not washed out like in bigger scopes.
Bill N.
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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desertrefugee
professor emeritus
Reged: 08/06/07
Posts: 526
Loc: Arizona
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I was using an ETX-90 MCT. I was able to confirm the split on Sunday night, but was not able to hold it steadily. I do believe seeing was the culprit. The air over Arizona has been on the move, I guess.
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"Look now upon the River of Heaven, Sky-Road of the Immortals, White with the star-frost of a billion years".
+++
-Darrell
Reflectors (114, 150, 254mm), Refractors (60, 76.2, 80, 120), MCT (125), way too many Binoculars
Cave Creek/Carefree, AZ
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ABC
sage
Reged: 10/22/06
Posts: 421
Loc: Heidelberg, Germany
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As always for tight doubles with difference in magnitude, seeing is the main limiting factor.
At good seeing, I can split this double cleanly at 115x and 91x with my 5" f/10 Mak and 6" f/9 ED, respectively.
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Kind regards, Christian
Meade 178 ED
Meade 152 ED
Intes Micro Alter M500
Bresser 70/700 Achromat
CGE
EQ-6
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SaberScorpX
Post Laureate
Reged: 01/12/05
Posts: 4121
Loc: illinois, usa
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LADIC is an interesting Difficulty Index calculator for doubles. Perhaps more consistent as a seeing-dependence curve.
http://usuarios.lycos.es/rbarbera/LADIC/index.htm
SJS
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desertrefugee
professor emeritus
Reged: 08/06/07
Posts: 526
Loc: Arizona
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Quote:
LADIC is an interesting Difficulty Index calculator for doubles. Perhaps more consistent as a seeing-dependence curve.
Outstanding link to an incredibly simply, yet useful application! Thanks for the tip. Just what an amateur doubles observer needs!
(Great, one more reason to lose sleep !)
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"Look now upon the River of Heaven, Sky-Road of the Immortals, White with the star-frost of a billion years".
+++
-Darrell
Reflectors (114, 150, 254mm), Refractors (60, 76.2, 80, 120), MCT (125), way too many Binoculars
Cave Creek/Carefree, AZ
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peashooter
member
Reged: 07/07/07
Posts: 76
Loc: Central USA
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This past Saturday with a 3-1/2" Mak-Cass @ 260x, Izar's pale blue secondary was located in the outer portion of the primary's first diffraction ring (from western KY under good seeing). It wasn't a challenge for newbies to see it.
Realize that despite superb transparency, the 30+ degree temperature difference between night & day in the AZ desert means turbulence as that pent-up solar energy is released at night. If your scope is portable, you might try looking at Polaris. It's not "going" anywhere, so you can use your highest power on it without having to align anything (although your tube should be acclimated to the ambient temperature). If you can't get a nice tight airy disc it means the seeing is suboptimal for splitting close doubles.
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Questar 3-1/2"
Zeiss 8X56
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desertrefugee
professor emeritus
Reged: 08/06/07
Posts: 526
Loc: Arizona
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Quote:
Realize that despite superb transparency, the 30+ degree temperature difference between night & day in the AZ desert means turbulence as that pent-up solar energy is released at night. If your scope is portable, you might try looking at Polaris. It's not "going" anywhere, so you can use your highest power on it without having to align anything (although your tube should be acclimated to the ambient temperature). If you can't get a nice tight airy disc it means the seeing is suboptimal for splitting close doubles.
Sage advice. Thanks for the "Polaris Calibration" tip.
Yeah, we have to take the good with the bad here. The good is 300+ clear nights. The bad? Heat radiation after dark. But, the delta is far less on the high Colorada Plateau (Mogollon Rim).
A short two hour drive to observing nirvana.
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"Look now upon the River of Heaven, Sky-Road of the Immortals, White with the star-frost of a billion years".
+++
-Darrell
Reflectors (114, 150, 254mm), Refractors (60, 76.2, 80, 120), MCT (125), way too many Binoculars
Cave Creek/Carefree, AZ
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peashooter
member
Reged: 07/07/07
Posts: 76
Loc: Central USA
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The sky must be awesome from the Mogollon Rim!
The drive back at 2 am must seem longer than the drive there.
An excuse for a pop-up?
S.
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Questar 3-1/2"
Zeiss 8X56
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desertrefugee
professor emeritus
Reged: 08/06/07
Posts: 526
Loc: Arizona
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It's the best sky I've ever seen. I never drive back. I generally take the tent for overnighters - or sleep in the station wagon. Actually, for those 4 day weekends (like weekend before last), I take the 5th wheel. Just don't tell the wife it goes off-road.
Believe it or not, my first glimpse if Izar was up there the last weekend in May. The color was very much like Alberio - but in my 10" Much less dramatic to my eye using the Mak back at home.
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"Look now upon the River of Heaven, Sky-Road of the Immortals, White with the star-frost of a billion years".
+++
-Darrell
Reflectors (114, 150, 254mm), Refractors (60, 76.2, 80, 120), MCT (125), way too many Binoculars
Cave Creek/Carefree, AZ
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diggy
sage
Reged: 05/09/04
Posts: 288
Loc: Vancouver Island, Canada
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I went looking for epsilon boo the past few nights, to check out my new WO Megrez 110 doublet. Both nights had reasonable seeing, but last night was exception here--at least 8 and I'd say occassionally 9 (very unusual for this area). I could not split Izar the first night. However, last night a clear split at 166. The little blue member of the pair was particularly delightful. This with a Nagler T6 9mm in a 2.5 Powermate.
I'm relatively new to the whole Doubles thing, and I'd say this was my biggest challenge so far.
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WO 110mm Megrez doublet on an HEQ-5 mount
Nikon 10x50 binocs
"Beyond here be there"
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1978
Loc: Florida
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Congrats diggy. Izar is a fine example of what your 110 can reveal. Now spend a dozen hours or so trying to split Antares.
Bill N.
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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diggy
sage
Reged: 05/09/04
Posts: 288
Loc: Vancouver Island, Canada
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Well, I can try. However, at my latitude, Antares is usually pretty low in the soup and over an urban area. It's going to take more than 10 hours. But, hey, there's no rush 
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WO 110mm Megrez doublet on an HEQ-5 mount
Nikon 10x50 binocs
"Beyond here be there"
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Clive Gibbons
Mostly Harmless
Reged: 05/26/05
Posts: 10307
Loc: Oort Cloud
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Hi Doug.
I've also used the Megrez 110ED with a 2.5x Powermate. At first glance, that combo seemed to work quite well, but when I compared it with using a conventional Barlow, the regular Barlow delivered a slightly sharper image with crisper diffraction rings. If I hadn't done a comparison, the difference might have gone unnoticed.
Not sure if all Megrez 110ED's work similarly with Powermates, but if you have the chance to try a high quality traditional Barlow with your scope, it might be worthwhile. 
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A few telescopes of dubious value.
Understanding wife and three curious cats.
"Semper ubi sub ubi"
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diggy
sage
Reged: 05/09/04
Posts: 288
Loc: Vancouver Island, Canada
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Good tip, Clive, thanks! I haven't had the time yet to do all the subtle comparisons of different eyepiece/barlow combos in the Megrez 110. But generally speaking, I'm pleased as punch with it.
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WO 110mm Megrez doublet on an HEQ-5 mount
Nikon 10x50 binocs
"Beyond here be there"
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1978
Loc: Florida
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This thread about Izar which is one of my favorites motivated me try it with my 2.4 inch Unitron. It was crossing the meridian and almost straight up and in good air. Stunning view at 187X. The secondary while pale in color was perfectly viewed sitting on the outside edge of the diffraction ring. It truely was a crisp view. Actually preferred the view compared to my 10 inch that I used a few minutes later. However the dim secondary had a more vivid blue/green hue than with the small refractor. In either case it was a pleasure to observe. Also proves to me Izar is well within the grasp of a 2.4 inch scope. Bill N.
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12561
Loc: Cumberland, R I , USA42N71.4W
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Bill,
I don't disagree that Izar can be seen with a 60mm. There is an old thread in here about how small a scope can actually still see it. But a 60mm scope has the center of the first diffraction ring at about 2.9 arcsec and the outside of that same ring perhaps at 3.1-3.2 arcsec. So, Izar (2.8 arcsec) hasn't got a chance of being placed on the outside of the diffraction ring as seen in a 60mm scope. It's right smack dab near the middle of it, in fact, leaning towards the inside. Perhaps the confusion lies in where you think the ring is???
Izar 60mm split
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1978
Loc: Florida
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That could be edz. For there is no question that it was clearly, sharply resolved. I remembered the old thread and was careful when I recorded my notes. It touched but favored the outside edge of what I perceived as the first diffraction ring. Its a small image and it could have gone either way... We are talking a few tenths of an arcsec here. Maybe that wasn't the first ring but being that it was touching the ring I think it was. A beautiful split none the less. Cheers, Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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KWB
Postmaster
Reged: 09/30/06
Posts: 7623
Loc: Westminster,Co Elev.1646Meters
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I've never managed to split IZAR with an F/15 60mm scope nor with either of my ETX 70's with so-so optics. Never with any short tube 80's nor my 66mm ED refractor. When the sky is steady I can do it with an 80mm ED refractor or my 90mm F/10 acro. This star take a fair amount of magnification to get the job done in my skies. To me this star is a great barometer of the nights seeing conditions. When I can split it the night holds promise. When I can't the viewing cession is usually short lived.
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Kenny
"When dealing with a mystery,choose the most unlikely of the likely possibilities"-Sherlock Holmes
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Tamiji Homma
sage
Reged: 02/24/07
Posts: 413
Loc: California, USA
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I checked out Izar a few minutes ago.
I tried at 225x, 187x and 117x with 102mm f/8.
All succeeded. Seeing is about average, tonight.
Tammy
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Clive Gibbons
Mostly Harmless
Reged: 05/26/05
Posts: 10307
Loc: Oort Cloud
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At the encouragement of a CN member who lives in the Tyneside area, I had a look at Izar last night with the Megrez 110ED stopped down to 58mm aperture.
Seeing was fair (about 6 Pickering).
At 131x, Izar showed a nice fat Airy disk with one concentric diffraction ring. The companion could be easily seen as a bluish "blip" on that diffraction ring. No ambiguity--smack dab on the ring. It was the only little blob or irregularity visible in the otherwise perfect appearance of the primary star. Upping the power to 205x showed it just as plainly.
At 110mm aperture, the companion appeared exactly where it did (in position angle) using the 58mm stop.
That was certainly the most "textbook" stellar diffraction image I've ever seen! 
Score one for small apertures. 
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A few telescopes of dubious value.
Understanding wife and three curious cats.
"Semper ubi sub ubi"
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Mr Onions
Not Amused
Reged: 04/14/07
Posts: 3579
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The only time I have ever seen text book airy discs and diffraction ring is with a 60mm stop over objective.
I wish I had better seeing conditions.
58mm Clive, thats a great achievement.
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Barchester Onions.
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1978
Loc: Florida
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Good report Clive. That's the smallest diameter scope I've read about that split Izar. Me thinks you're close to the minimum aperture required for the view. It would be interesting to find the cut off point.
Thanks for posting. Bill N.
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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Clive Gibbons
Mostly Harmless
Reged: 05/26/05
Posts: 10307
Loc: Oort Cloud
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Thanks for those kind words. 
The next clear night, I'll try 55mm...
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A few telescopes of dubious value.
Understanding wife and three curious cats.
"Semper ubi sub ubi"
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ylin
sage
Reged: 05/23/05
Posts: 239
Loc: Irvine, CA
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Last night was the first time I saw Izar. With my 80mm scope, I split it around 139x (4mm of TV3-6 Z00m), but it was 185X (3mm) to give a very nice view.
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Yusen
Meade 102ED/LXD650
William Optics ZS80FD/AstroTech Voyager [天鵝牌紅標米洒]
SVF50B2
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KWB
Postmaster
Reged: 09/30/06
Posts: 7623
Loc: Westminster,Co Elev.1646Meters
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150X sounds just about right with a steady sky and an 80mm F/11 refractor,Yusen. That's also about the magnification it takes for me to split this star with my 90mm F/10 refractor.
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Kenny
"When dealing with a mystery,choose the most unlikely of the likely possibilities"-Sherlock Holmes
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CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1811
Loc: Morganton, GA, USA
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Got a very clear split tonight on Izar with my TMB 92SS at 102x (5mmT5 Nagler) under slightly better than average seeing.
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CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1811
Loc: Morganton, GA, USA
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Tonight I went back with my TV-60mm scope to look at Izar. Seeing was average, but there was little difficulty splitting Izar at 180x. I then started backing off the Nagler 2-4mm zoom. Still visible at the 2.5 (144x) and even 3mm (120x) settings. At 3.5mm (103x) it was starting to approach the limit of visibility and that may have been only because I was coming down from a higher power - if I was coming up from a lower power, I might not have noticed this as easily. At 4mm (90x) it was definitely not possible (meaning not possible for me of course). But moving back to 103x, it was just barely visible when the seeing steadied. The TV60 has particularly fine optics and although relatively fast at F6, at this objective size, it's not a major problem to produce tack sharp images with a doublet at this F-ratio.
Anyway, this experience suggests that with a really fine objective one might be able to get down to 55mm or perhaps even 50mm and still catch Izar's companion under superb viewing conditions.
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JeffB
member
Reged: 06/05/07
Posts: 23
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I have a WO ZS66SD and can see the Izar's companion as a definate brightening about in the middle of the diffraction ring of the main star. I need quite a bit of magnification using 5x powermate. From mememory about 10' o clock position using a normal star diagonal. Is this correct. I dont have a larger telescope to confirm this
Jeff
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Clive Gibbons
Mostly Harmless
Reged: 05/26/05
Posts: 10307
Loc: Oort Cloud
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Quote:
Anyway, this experience suggests that with a really fine objective one might be able to get down to 55mm or perhaps even 50mm and still catch Izar's companion under superb viewing conditions.
Yes, 50mm did it, but a much tougher observation.
Posting here.
--------------------
A few telescopes of dubious value.
Understanding wife and three curious cats.
"Semper ubi sub ubi"
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Perka
member
Reged: 04/13/07
Posts: 36
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