Zeta Herculis

[NGC 1502]

 

Last night was clear in SE Essex, but I nearly didn’t go out, not long past full moon and the lingering twilight.  However I’m so glad I did because it superb for double stars.

The highlight for me was Zeta Herculis ( Struve 2084 ) the SW star in the keystone.  I had two scopes in use, my OO 10” Dob designated 1/4 wave, and a new to me OO 8” VX8L, designated 1/10 wave.   I’ve had many unsuccessful tries at splitting Zeta with the 10” and last night was no exception.  Last night the seeing was so good that I tried magnifications that are usually pointless.

With the 8” at 300x and then 400x I got a lovely clear pin point split.  Bit of a challenge hand tracking at those mags with the 50 degree apparent field zoom, but definitely worth it 👍

I wont go into what 1/4 wave and 1/10 wave actually mean, different interpretations about that..........

Both scopes fully cooled and collimated, chuffed with the 8” previously owned by a local club member sadly no longer with us.

Ed.

 

 

[John]

Great report Ed and congrats on getting Zeta Herc !

I've had a mild obsession with that binary star for sometime now. I first managed the split with with a 150mm F/8 refractor, then eventually with my ED120 and now I've managed it with the Tak FC-100. It's a challenging pair alright with it's closeness and uneven brightness and a stern test of observer, conditions and equipment.

I agree that it's when you are observing targets that push towards the limits that quality optics show their worth.

 

[Stu]

Great stuff Ed. This one has been my nemesis for a few years! I seem to remember seeing it once before, possibly in Gavin's TEC160, not sure.

I'm reckon John's seeing must be better than mine, as I've tried and failed on numerous occasions with my Tak, and other larger scopes in the past.

I do now have an Orion Optics 8" f8, 1/10th wave, so given your success with your VX8L, it seems possible I will have some luck with it.

Thanks for the report.

[JeremyS]

2 hours ago, Stu said:

This one has been my nemesis for a few years!

This has surely got to be one for the Mewlon 210, Stu!  🙂

 

[Stu]

1 hour ago, JeremyS said:

This has surely got to be one for the Mewlon 210, Stu!  🙂

 

Yep, will give it a go. Need to get away from home to get some better seeing though. At home I'm observing over the houses most of the time.

[alan potts]

Nice report, from memory I have split it with the M/N 190mm. My skies are very good here (most of the time) and I don't recall it being a difficult one, but if you have had problems with a 10 inch, then it must be, maybe it is all about conditions like Sirius.

Alan

[NGC 1502]

 

Thanks all.  Earlier in the evening the split was not seen, had to wait until the Hercules keystone was almost overhead, then the 8” revealed the secondary occasionally and then for long moments.......two pinpoints imbedded in the diffraction rings.

I also appreciated the two speed focuser making exact focus easier to achieve.  Never had a two speed before, and used to wonder if it was necessary.  Mind you the focuser needed several previous tries to adjust it to make it work ok, at first it was way too tight, then it slipped, but eventually got a reasonable compromise.

I just love the Cambridge double star atlas ( second edition ) full of targets to entertain at all seasons.

Ed.

[NGC 1502]

 

An update on splitting Zeta Herculis.    This evening in SE Essex the sky conditions were poor, veil of thin high cloud blanking out most of the sky.   But I thought I’d have a session splitting some bright and easy to find doubles using my 6” f6 Dob. This was the scope that got me back into astronomy in 1994 having given up a few years before that.  It was a DIY project using a David Hinds mirror set.  This scope doesn’t get much use as I have more telescopes than I’d like to admit................🙄

By now you can guess what’s coming, in a murky but steady sky, the little Dob split Zeta at 200 then 300x.  I realise that’s very high power for a 6”, but double stars take high power well.   Steady skies plus excellent optics can surprise us.

One thing this shows - when you get a larger scope(s) best to keep your old one if you can,  it will come in handy.

Ed.

 

Edited July 24, 2019 by NGC 1502
extra info

[John]

Very good split for a 6 inch F/6 newt. David Hinds knew how to make a good mirror though

 

[chiltonstar]

Ed's point about focus is a good one - the secondary is on or close to the first diffraction ring of the primary and if the scope is even a tiny bit out of focus, the secondary just becomes a "brightening" of the diffraction ring to me rather than a pinpoint. With my 180 and 127 Maks I split it fairly easily in good conditions, but it takes a bit of a wiggle with the Baader helical focuser to get it dead right.

Chris

[NGC 1502]

 

Hi Chris, that’s great getting a split with a 5” Mak.     The Maks I’ve looked through had very sharp optics, often described  as “refractor like” - a well defined Airy disc with one or two diffraction rings.     At high power that’s how I would describe Zeta Her with my 6” F6.

Also last night in those hazy conditions I viewed the double-double, 61 Cyg, Raselgethi,  Izar, etc.  Hardly ground breaking but good fun in a relatively poor sky in the middle of a large town before it had got fully dark 👍 👍

Just thin trousers tee shirt and flip flops was a bonus.......

Ed.

[Whistlin Bob]

Nice report! I didn't even know it was a double... For me it's the star that tells me I've gone way too far when looking for m13! Now I have an added little objective next time I observe 😁

[Paz]

Nice report, that double is a good one for me as soon its easy to remember and easy to find without a map or a computer or a star hop, but not so easy to split.

[Paz]

On 22/05/2019 at 15:09, Stu said:

Yep, will give it a go. Need to get away from home to get some better seeing though. At home I'm observing over the houses most of the time.

I have realised over time I have this issue quite often  at home - heat from houses and roads can be as annoying as light pollution when it comes to limiting what can be seen.

[John]

With these really tight doubles, if possible, I try and wait until they are at their highest point in the sky when trying to split them. A little less atmosphere to peer though and further from the LP and other stuff that intrudes into the sky from my horizons.

 

[Whistlin Bob]

Yes! Just split it in 14" dob with aperture mask 😁😁😁😁

Thanks again for pointing it out.

[John]

I got it nicely this evening with my ED120 refractor. Pi Aqullae as well.