Zeta Herculis - have you ever managed a split?

[Moonshane]

Hi all

I often try to split Zeta Herculis when seeing is good but never actually manage to do so. This is a close double which changes the degree of separation over a reasonably short period. I suspect it is current in one of the closer phases.

Has anyone ever managed to split this bright double star? Try as I might last night I could not do so even with my 6" f11 at 533x in good seeing. The airy disk seemed somewhat one sided (not collimation!) so maybe this indicates that the secondary was distorting the shape of the pattern?

Cheers

Shane

[John]

I had a "suspected" sighting with a 6" refractor a couple of years back. It was more of a bump on the side of the airey disk of the brighter component to be honest so I'm unsure about it.

I posted this about that observation but I'm doubtful of it now - the PA of the companion could be all wrong:

[Moonshane]

cheers John. I think it was your post that started me looking in vain! might try it with my 16" next time out.

[Kai]

Ian would be the guy to ask (Lunator) ,

[LDUNN1]

ohhh thx for this post!

I am relativley new to astro, & up to a week ago had not started to try & split doubles, but last Friday I decided to have a go on the lyra double double - so not as challenging as the one you are attempting, but I was very pleased to see an easy separation - I believe the conditions were very good on that night for my neck of the woods mind.

Next time I'll give your one a go as the 'next step', but it sound 'tough' so I'm bracing for failure, but it will be fun to try at least.

[John]

This section of the forum might have some good targets too:

http://stargazerslounge.com/forum/52-observing-and-imaging-double-and-variable-stars/

[Moonshane]

Finally manged a good split last night. I'll add further details in due course.

[Moonshane]

Scope 16" f4 manual dobsonian (masked to 170mm f11). eyepiece 6-3mm Nagler.

I found that I could only confidently split using the eyepiece at 4mm (460x) and that at 3mm (613x) the split was obvious in moments of good seeing. primary was yellowish white and secondary pale brick red. it sat on the first airy ring I think. I repeatedly returned to the double and saw the same thing and my observing buddy described what I saw unprompted. I am 100% confident that I managed a split.

[Moonshane]

I had a "suspected" sighting with a 6" refractor a couple of years back. It was more of a bump on the side of the airey disk of the brighter component to be honest so I'm unsure about it.

I posted this about that observation but I'm doubtful of it now - the PA of the companion could be all wrong:

http://stargazerslou...re/#entry655376

hi John

I have to say that your sketch represents very well what I was seeing. your description of the star colours also match what I could see. I have no way of measuring PA but I am 100% sure I managed a split.

[John]

Thanks for those reports Shane and well done !

I'll have another bash at this one tonight hopefully - I'll post my findings. It's quite a "toughie", probably the toughest I've attempted. Sounds like I may have got it on the earlier attempt after all

[Moonshane]

I actually believe you did mate. Even though it seems a bit mad, try the highest powers you can achieve. This really did make the difference for me and I am totally convinced I split it. it's very well placed currently and I think tracking at such powers felt a bit easier last night due to this. good luck

[John]

I've managed to more or less replicate the views that I posted above tonight using a 6" F/8 refractor fitted with a William Optics VR-1 filter and using a Nagler 3.5mm for 343x - thats my max power eyepiece at the current time. Your description of the the dimmer star's "pale brick red" colour seems very sound to me Shane. I saw the primary as being pale lemon. I have to bear in mind that I'm using an achromat with a CA correction filter so the tints may be affected a little by that combination. The split was a hairline one.

It is very interesting to compare Zeta Herc with Pi Aquillae. The separation is the same according to my data at 1.4 arc seconds but the much wider variation in brightness between the components of Zeta Herc makes it seem a closer pair.

Good fun and thanks for sharing your observations Shane

I'm off to find an equal brightness pair with a 1 arc second separation now

[Damo636]

Well done guys, I am looking forward to having a crack at this one. I can get up to a max of 400x with the 6mm/barlow combo so hopefully thats enough juice to seperate them :-)

[estwing]

yes well done, this is an area of astronomy that i have never looked into...always willing to try something new!

[Moonshane]

Well done guys, I am looking forward to having a crack at this one. I can get up to a max of 400x with the 6mm/barlow combo so hopefully thats enough juice to seperate them :-)

I'd recommend making a mask with as big a diameter hole as will fit between your vanes - you might manage about 120mm. this will probably susprise you with the sharpness of views and perfect rounded stars with no diffraction spikes.

[mdstuart]

I love that Pi Aquarius..1.4" .In my 10 inch dob with the 4mm eyepeice it splits pretty well but its close.

Mark

Will try the mask idea!

[Damo636]

I'd recommend making a mask with as big a diameter hole as will fit between your vanes - you might manage about 120mm. this will probably susprise you with the sharpness of views and perfect rounded stars with no diffraction spikes.

I'll give the mask a go Shane. I've had a quick gander at the spider and you're right, I might just about squeeze in a 120mm (ish) hole between the vanes. Its completely clouded over here so it'll give me a chance to knock together a nice 120mm f12.5 "apochroflector"

[Moonshane]

I am pretty sure based on my old 12" that a CD is just the right size. you'll be surprised I bet at the improvement on point sources like doubles and bright objects like planets and moon. even though you lose a little resolution, you cannot benefit from this most of the time due to seeing.

[Damo636]

I had a brief session last night before the clouds rolled in with my 12" dob masked down to 120mm f12.5 as per Shanes advise. It was so odd to view bright stars with the dob without defraction spikes but theres no doubt about it, it really does tighten up the star into a refractor like pinpoint. What I knocked up isn't pretty, a sheet of cardboard with a CD size hole cut in it & held in place with gaffer tape. I see that TS sell replacement lids for GSO scopes for about a tenner so I think I'll order one of those and make a more "professional" looking effort :-)

[John]

Managed a short session tonight in between cloud banks with the 6" F/8 Skywatcher frac. Pi Aquilae v.nicely split at 300x. Zeta Herc looked as described by Shane earlier in this post including colour tints. Interestingly I found the splits of both better defined and more pleasing without the minus violet filter in place. The filter did reduce the CA around brighter objects but seems to introduce a little more light scatter when viewing stars, which does not help with tight binaries of course !

Wish I could have had a longer session but the jet stream seems to have shifted south again bringing the multiple rain fronts with it

[chiltonstar]

When the skies finally cleared again last night for an hour, I had a look with my 5" Mak; I've never bothered with this one before as I assumed it was out of reach with such a small scope, although several reports above indicate otherwise. Struggled for 30 minutes without any luck, and then had a spell with better seeing before the Dew descended...!. I'm pretty sure I could see the secondary, well within the first diffraction ring of the primary. I'll check the angle though to be sure.

Chris

[chiltonstar]

When the skies finally cleared again last night for an hour, I had a look with my 5" Mak; I've never bothered with this one before as I assumed it was out of reach with such a small scope, although several reports above indicate otherwise. Struggled for 30 minutes without any luck, and then had a spell with better seeing before the Dew descended...!. I'm pretty sure I could see the secondary, well within the first diffraction ring of the primary. I'll check the angle though to be sure.

Chris

I estimated the PA from the direction of drift in RA, and applied the vertical and horizontal flip for a Mak, ending up with about 130 to 140. which seems close enough to the estimate from the 6th Orbital Catalgue with a correction of minus 9 degrees per year, giving about 133 degrees. What I saw was very similar to a sketch on this forum 2 years ago, but with the secondary just inside the diffraction ring, and perhaps more of a disk.

Chris

[John]

Sorry to resurrect this old thread but I've just managed a split of Zeta Herculis with my ED120 refractor. The secondary star appears on the outer edge of the diffraction ring of the primary star and has a greyish look to it and is somewhat dimmer than it's close companion. First indications that this was going to "go" came at 257x but the split was clearer at 289x and even 338x !.

The view was similar to that shown in my rough sketch linked to earlier in this thread but the image was much crisper and steadier tonight.

The position angle seems to be correct so I'm fairly confident I can claim the split

Good conditions for binary viewing tonight

[chiltonstar]

Well done! What's the next difficult target?

Chris

[John]

Well done! What's the next difficult target?

Chris

Thanks Chris,

I also manged Mu Cygni last night but I'm not sure thats as challenging as Zeta Herc to be honest. The close pair were split at 257x but the fainter members of the group were not visible as that part of Cygnus had not really cleared the Bristol "murk" when I was viewing.