Zeta Herculis - have you ever managed a split?

[Mark at Beaufort]

John - thanks for the reminder of this close double. I bought a 180 Mak a few weeks ago, mainly to view more doubles. Hopefully I will have a go at Zeta Herculis tonight.

Mark

[John]

John - thanks for the reminder of this close double. I bought a 180 Mak a few weeks ago, mainly to view more doubles. Hopefully I will have a go at Zeta Herculis tonight.

Mark

Let me know how you get on Mark

I've just sold an 180 Mak for a friend, as it happens.

[John]

I confirmed Zeta Herc with my 12" dob tonight. Clearly confirmed the split that I made with my ED120 last night. Nice

[Mark at Beaufort]

Was not successful with the 180 Mak. I used the 13mm Ethos (208x) and 8mm Ethos (337x) and then the Baader zoom with its barlow which went up to 771x. I had a sharp image of Zeta but no sign of a companion. I will try with the 10 Dob to see if I get any joy.

Mark

[John]

I'm surprised at that Mark. I would have though the Mak would show it reasonably clearly

The secondary star does "hug" the primary pretty closely and is somewhat dimmer. Did you have a diffraction ring around the primary star ?

[Mark at Beaufort]

Did you have a diffraction ring around the primary star ?

Yes I did John. I looked at your sketch this morning which you produced a few years back. From the comments in your thread I assume that your sketch related to the view in a Newt? Am I correct?

Mark

[John]

I did the drawing from the view I had with a 6" refractor back then. I then flipped the drawing to replicate the newtonian view before posting it on the forum. Looking back at it I wonder if I've flipped it incorrectly as I recall from last night that the dimmer companion star was on the other side of the primary through the newtonian.

I'll have another look tonight if possible and try and produce a more definitive sketch then.

[Mark at Beaufort]

John I found this diagram on the internet. Because I am using a Mak Cass with a diagonal I assume that I should be seeing the secondary on the opposite side to this first diagram.

Mark

[Doley68]

Hello chaps,

I spent some time trying to split zeta last night with my 180 mak and had a hint of a split at x300. It was definitely there but only occasionally.

Could have done with a higher power really but haven't bought that eyepiece yet (any suggestions).

The diagram of the orbit needs to be flipped horizontally to match a mak and diagonal I believe, so the companion is at about 5 o`clock..

This is a really tough target. I'll have another crack at this one over the weekend!

[John]

The 6mm Ethos (267x) was the first eyepiece that showed the split for me with my 12" scope. It was a little clearer with the 5mm Pentax XW (318x). With the ED120 refractor it was the XW 3.5mm (257x) that did the trick and then a 7mm Hutech ortho barlowed 2.25x with the Baader Q-Turret barlow (289x).

I'm going to produce another drawing on the next clear night.

[Mark at Beaufort]

Since posting thread 33 I have looked again at the diagram that I found on the internet. I now realise that its showing the position as looking through a Newt. North should be P.A. '0 degrees' and therefore at the top with west P.A. 270 degree on the right.

This means in a Mak Cass the image should be as Doley68 stated above at about 5 o'clock. Thanks Doley68 it made me look again.

Mark

[John]

That looks correct to me now Mark. It's easy to get confused though isn't it ?

If you invert that diagram (S / 180 deg at the top) you get the newtonian view (E & W still reversed of course) which does seem to correspond more or less with the position angle I was seeing the secondary star in with my dob.

Hopefully we will get another shot at this over the weekend and can all produce sketches for comparison !

[Mark at Beaufort]

Thanks John at least I know the true direction of the secondary now. Hopefully, I will get a chance over the next few days.

I know this is off topic but the views of Saturn with the Mak and binoviewers is better than I expected.

Mark

[John]

I know this is off topic but the views of Saturn with the Mak and binoviewers is better than I expected.

Mark

They are good scopes. I had a quick go with the one I was trusted with selling, to check it's collimation, and it did produce some great images of the Moon and Saturn. That was in mono mode with the standard diagonal.

[Doley68]

Glad I could help a little with the PA.. It can be a little confusing.

The view though a mak with diagonal makes it quite simple though.

0° is at 12 o'clock, 90° is at 3 o'clock, 180°is at 6 o'clock and 270° is at 9 o'clock. Just as you would draw a circle on a piece of paper.

This is because as you view with your naked eye 90° is at 9 o'clock, and the mak flips left to right!

Clear as mud? He he.

Chris.

[John]

I'll be trying it with the refractor tonight so the orientation will be the same as a mak.

[John]

Well the seeing is really top notch here tonight - I've been able to use some stupidly high magnification with my ED120 - 578x on Delta Cygnus and Zeta Hercules and still decent airey disks and a fine diffraction ring around the brighter component stars.

I've done a little drawing of Zeta Herc at a slightly more modest 338x which I'll scan and upload ASAP. The position of the secondary star seems to match the above diagram although it's ariey disk seems a little elongated, possibly because the diffraction ring of the brighter component passes right through it !.

[John]

Here is my rather rough sketch. ED120 refractor , 338x (7mm Hutech Ortho + Baader Q-Turret 2.25x Barlow). To my eyes the primary star is pale lemon and the secondary somewhat dimmer and pale greyish maybe even grey / green. Obviously the sketch enlarges the star considerably over the view through the eyepiece !:

[John]

Looking again at my sketch and the object, the secondary star is fainter than it appears in the sketch - closer to the brightness of the diffraction ring, although clearly a different hue, through the eyepiece.

[Marki]

Thought I'd give this a go for fun . No sign at all at below x300 and I only had a very feint hint of this when I got to x361 (9mm TMB clone with powermate 2.5 in the skylight 4" f13 'frac) - wasn't a clear split but a suggestion of a small "bulge" on one side of the star. Pushed it to x464 (7mm bgo in the powermate 2.5), but again only a hint and I think I lost it in the diffraction ring - what I was seeing suggested something much feinter and smaller than your sketch, John, but I didn't have time to get my eye before the clouds rolled in and I had to give up. I'll have to give it another go next clear night. Also, pushing the magnifaction, maybe my collimation is very slightly out, hadn't noticed before - don't think I've ever pushed it above x 275ish before.

Guess it'd be easier with more aperture?

Until it clouded over, I thought it was quite good conditions - got a nice easy split on epsilon lyra and just managed clear separation at x65 - I think thats my best effort to date, so happy with that.

[John]

I've had another go at the contrast in my sketch. I reckon this more accurately portrays the brightness difference between the primary star and the secondary:

[chiltonstar]

I've had another go at the contrast in my sketch. I reckon this more accurately portrays the brightness difference between the primary star and the secondary:

Pretty accurate IMO - with my Mak the secondary is a smaller diameter (almost pinpoint) but the relative brightness looks right....

Chris

[Mark at Beaufort]

Well I tried and I just cannot see the secondary. I used both the Mak 180 and my 6" Newt both of which I think are well collimated. I pushed the mag to 337x had the diffraction rings but I cannot split Zeta. I will try again.

Mark