Double star Zeta Herculi between clouds

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John Baars Netherlands
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Double star Zeta Herculi between clouds

#1

Post by John Baars »


Bad weather going on for weeks. It is frustrating. Not funny any more.
Last Sunday it was clear for some hours, but the next depression was on its way. In fact it was a race between the slowly darkening Summersky and the fast advancing cloud fields from the Southwest. An observing window of one hour.

One of the observers on TSS had mentioned Zeta Herculi as a nice doublestar. Thanks! I didn't even know it was double! Nice opportunity to observe it. Magnitude A 2.8, magnitude B 5.4, separation 1.5". Questionable with a nonperfect 102mm Maksutov. The moment I saw Vega with the naked eye I put out my grabngo 102mm Maksutov on AltAz. Observing Vega is one thing, observing a magnitude 3 star like Zeta Herc in the twilight is something different. So I had to wait. Meanwhile the cloud-devils were coming in..

Finally I could see him and put him in the 100X field. Nothing whatso-ever. So I put in the normal max. I use on this telescope, 150X. Quite uncertain. In fact still a "NO". So I took out a 6 mm orthoscopic and put it in, 225X. Quite over the top. The seeing hindered, but most of the time I was able to see a slight bulge which apparently should be the B-component. Very soon after it was over again.

In the image below ( made in Aberrator) you can see how it looked like. The top image is like how a normal star looks like. The bottom one has a companion of the right size and on the right distance. Not really easy, but visible.
Zeta Herculi.png
Thanks for reading!

Have you got a minute?

Furthermore the image shows a lot of aberrations which you can fill in yourself in the program.

+Coma- just a bit. 0.05 Wave distortion, which is very low.
+Astigmatism- haven't seen it. Glad too.
+Lower Spherical aberration- somewhere around 0,3 Wave undercorrected, a bit too much as a matter of fact, since 0.25 is the limit for a "C". It causes a fatter first diffraction ring than it would be without this aberration.
+Higher Sperical aberration- in this case a zone in the mirror that causes a slender bright ring far outside the first thick diffraction ring. 0.4 Wave is too much. In or out focus a zone is visible as a well visible brighter or darker ring within the defocussed star.
+Pinch- a bit of pinching, not much. Hmmm, It would be better if it was not there.
+Tube currents. In our case I haven't seen them, since the telescope was out more than an hour and isolated as well.

In the graphics:
+ Modular Transfer Function. As a result of the central obstruction and the rather severe aberrations contrast in the telescope doesn't follow the ideal track. The straight line is the ideal one. The dotted line is my telescope. In the mid-zones there is a dip. You would hardly notice it, but very obvious if side by side compared with an ideal telescope. Which was not the case, lucky me.
+ Point Spread Function. A bit comparable with the famous Strehl-number.The extent to which the telescope is able to get the collected light in one point (the Airy disk). 0.8 is "C". 0.78 like mine is "D". Near perfection top telescopes come as far as 0.98- 0.99, but they tend to make a black hole in your wallet.

The rest speaks for itself.
Thanks for reading so far!
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
Amateur astronomer since 1970.
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helicon United States of America
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Re: Double star Zeta Herculi between clouds

#2

Post by helicon »


Thanks for the detailed report John and congrats on winning the VROD for today!
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Double star Zeta Herculi between clouds

#3

Post by KingNothing13 »


Sounds like a challenge with the conditions John - hopefully it gets easier.

Congrats on the VROD.

Last night was predicted to be clear here, first night in WEEKS - and it was - but the sky was so filled with humidity that only the brightest stars shone through. It would've been a frustrating night if I tried to observe.
-- Brett

Scope: Apertura AD10 with Nexus II with 8192/716000 Step Encoders
EPs: ES 82* 18mm, 11mm, 6.7mm; GSO 30mm
Celestron SkyMaster 15x70 Binoculars
List Counts: Messier: 75; Herschel 400: 30; Caldwell: 12; AL Carbon Star List: 16
Brett's Carbon Star Hunt

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Re: Double star Zeta Herculi between clouds

#4

Post by mikemarotta »


Congratulations! Louis Pasteur said that chance favors the prepared mind. You grabbed the brass ring.
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Michael E. Marotta
Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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Re: Double star Zeta Herculi between clouds

#5

Post by Unitron48 »


Nice capture, John! Congrats on the VROD!!

Dave
Unitron (60mm, 102mm), Brandon 94
Stellarvue SVX127D
http://www.unitronhistory.com

"Look deep into nature, and then you will understand everything better." Albert Einstein
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Re: Double star Zeta Herculi between clouds

#6

Post by kt4hx »


Well done John and congrats on the VROD. Bad conditions - what is that? :)
Last edited by kt4hx on Tue Jul 06, 2021 10:17 pm, edited 1 time in total.
Reason: Ooops, meant "bad" instead of back!
Alan

Scopes: Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob ||
ES AR127 f/6.5 || ES ED80 f/6 || Apertura 6" f/5 Newtonian
Mounts: ES Twilight-II and Twilight-I
EPs: AT 82° 28mm UWA || TV Ethos 100° 21mm and 13mm || Vixen LVW 65° 22mm ||
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Filters (2 inch): DGM NPB || Orion Ultra Block, O-III and Sky Glow || Baader HaB
Primary Field Atlases: Uranometria All-Sky Edition and Interstellarum Deep Sky Atlas
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"Astronomers, we look into the past to see our future." (me)
"Seeing is in some respect an art, which must be learnt." (William Herschel)
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Re: Double star Zeta Herculi between clouds

#7

Post by Gordon »


Congratulations on the VROD!

Great report!
Gordon
Scopes: Explore Scientific ED80CF, Skywatcher 200 Quattro Imaging Newt, SeeStar S50 for EAA.
Mounts: Orion Atlas EQ-g mount & Skywatcher EQ5 Pro.
ZWO mini guider.
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Re: Double star Zeta Herculi between clouds

#8

Post by Bigzmey »


Congrats on the difficult split and VROD John! Pulling split like this makes you feel really good about your skills and equipment.

Your reports also illustrates two rules I keep reminding myself:

1) Don't be afraid to use high powers, even on galaxies
2) If everything else fails - try Ortho. :)
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: Double star Zeta Herculi between clouds

#9

Post by Makuser »


Hello John. A very nice and well written report from you, despite the lack of sky cooperation. I am glad that you got to split the double star Zeta Herculi with the 102mm Mak telescope and a lot of patience. Thanks for your excellent report John, and congratulations on winning another TSS VROD Award.
Marshall
Sky-Watcher 90mm f/13.8 Maksutov-Cassegrain on motorized Multimount
Orion Astroview 120ST f/5 Refractor on EQ3 mount
Celestron Comet Catcher 140mm f/3.64 Schmidt-Newtonian on alt-az mount
Celestron Omni XLT150R f/5 Refractor on CG4 mount with dual axis drives.
Orion 180mm f/15 Maksutov-Cassegrain on CG5-GT Goto mount.
Orion XT12i 12" f/4.9 Dobsonian Intelliscope.
Kamakura 7x35 Binoculars and Celestron SkyMaster 15x70 Binoculars. ZWO ASI 120MC camera.
>)))))*>
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