What a mirror

[alan potts]

I have had my largest scope now for just over a year and the quality of the optics made by J Nichol over in England never stop amazing me, the only area where they have let me down is the Horses Head and I really feel that is only because it is off either appearing in a film or running at a night race meeting. Something that I did find very surprising was that when I put the scope together, it is a 3 part affair with truss poles, was that it was in perfect collimation using the laser and I didn't need to tweek anything. I cannot recall that happening before.

I had a very quick look for the HH last night but it really was half hearted failure as I wanted to try something else that has been on my mind for a few weeks since reading about it on site. I cannot recall if it was Nick ( Cotterless ), who if he played tennis would have been a doubles champion or Stu but whoever it was was taking about Sigma Orionis. This is a 5 star group where the main AB system is a very small 0.25 arc seconds apart, this being either at or very close to the limit at which my scope can resolve the two stars, a stern test.

Sirius always draws me in and I could not resist a look to see the Pup again and the 17mm delivered at X134 though it was fickering in and out of visibility which I thought strange as the main star looked more stable than it usually does with no real signs of scintillation as yet, but that normally kicks in as it gets darker.

Now I didn't think seeing was too bad as I had been looking at some wonderful belt structure on Jupiter at X229 with the 10mm Ethos and everything appeared to hold up very well, I tend not to push Jupiter beyond X200 most nights as I always feel that less is more on this planet. However things looked amazing as moons came from behind and infront of the main disc with very little time gap, it was a hive of activity last night as I was waiting for dark to fall, sort of reminded me of Kings Cross at rush hour. There was also what appeared to be a dark spot on the upper equatorial belt, which would be the southern belt in this scope, this stood out fairly well and I don't believe it was a shadow of any type as it was just too large and not dark enough. It also was not the GRS as this is unmistakeable and the spot comes across very red in this scope. Stunning clarity from the 18 inch mirror and the various eyepieces made by Televue had already made it a good night and it was not even dark.

As darkness fell I turned my attention to Sigma Orionis a very interesting doubles system just below the Alnitak and close to the famous Horses Head ( if it exists ). I had read a little about this group on Wiki and it tells about the E component being a strange star very rich in Helium and I am guessing with it being 'E' it is the faintest of the group, which was easy to see with the 31mm Nagler giving X73, about my lowest power. I moved up to the 17mm Ethos, this increases the magnification to X134 with the Paracorr in the optical path and even at this power I could see there was something odd about the main star, it was a funny shape, seeing was holding well. I increased to the 10mm and at X229 the main star was even more out of shape and hinting that there was two parts to this but was not showing a gap of any kind that I could decern, I didn't believe that I had to push much harder though to see them as two but was wondering if seeing would prevent this. I went to the other case to get the 8mm and 6mm which I do not use that often in this scope, firstly trying the 8mm which serves up X286, on a good night this is well within the powerbands of this scope having pushed it before to well over X500, albeit on the Moon. There it was, not all the time split into two parts but every now and then being able to see the smallest of gaps and two distinct stars whereas before there had been one eliptical one. The mirror had delivered at what must be very close to its theoretical ability, that put a smile on my face, not that anyone could see it.

Maybe now it is something for someone with a 16 inch to try to see if it is possible with a slightly smaller scope.

Alan

   

[FenlandPaul]

Wow, that's a really impressive split, Alan.  Says a lot about your mirror, collimation, eyepieces, seeing and eyesight!  It's all got to come together, and it seems to have done.  Nice report.

When you do finally track down the HH, I suggest you rename your observing site the Knacker's Yard Observatory.  

[avtaram]

I observed Sigma Ori last year with my 150PL and just managed to see the companion to the main star as a little pimple on it.

Avtar

[bingevader]

Sounds like a rather splendid night out!

I'm sure J Nichol would be interested in this as a review of the quality of their mirrors.

[Paul73]

Nice report Alan .

That is a cracking target. Did you get much colour variation? This can be a very colourful little system. But, that could be, one of the very few, pleasing aspects of our unstable UK sky.

Paul

PS. The A/B star looks pretty round in my 10" pea shooter.

[Stu]

Fabulous report Alan, at your best ??

I think I can take at least some of the blame for you investigating this target as I enquired about the AB split on a sketch a little while back which led to some good discussion.

Pretty amazing stuff, as you say the combination of aperture, a very smooth mirror with low scatter and excellent seeing conditions, and I'll add observer skill, all make the difference to seeing targets like this. Nice one.

Old Nick will be leaping up and down in celebration at this one!!!! ???

[Stu]

3 hours ago, avtaram said:

I observed Sigma Ori last year with my 150PL and just managed to see the companion to the main star as a little pimple on it.

Avtar

The C star is quite easy with a decent scope, faint but separated quite clearly from AB in my 4" Tak.

Alan is referring to the almost mythical AB split which is extremely difficult and beyond the reach of a 150P or any scope I've had (up to 16"). I'm sure the mirror quality makes a big difference at these powers.

[laudropb]

Lovely report and a great split. It's always nice when everything comes together. Well done.

[faulksy]

nice one alan, as you say great mirror, glad your loving it

[alan potts]

38 minutes ago, Stu said:

 excellent seeing conditions, and I'll add observer skill, all make the difference to seeing targets like this.

Old Nick will be leaping up and down in celebration at this one!!!! ???

Thanks Stu most kind of you to say, I am sure it could be done with a 16 inch given like conditions or better with maybe a bit more power. I did use but didn't mention use of the 6mm Ethos giving a whopping X381 but there was nothing to be gained that I could see, I didn't see a better split just a less clear view in general. As I am sure you know there is a line to be drawn that is always down to conditions, this scope in the right part of the world can handle maybe X600 or greater, but not here alas.

Alan

[Stu]

9 minutes ago, alan potts said:

Thanks Stu most kind of you to say, I am sure it could be done with a 16 inch given like conditions or better with maybe a bit more power. I did use but didn't mention use of the 6mm Ethos giving a whopping X381 but there was nothing to be gained that I could see, I didn't see a better split just a less clear view in general. As I am sure you know there is a line to be drawn that is always down to conditions, this scope in the right part of the world can handle maybe X600 or greater, but not here alas.

Alan

Quite possibly correct about a good 16" being able to do it. I didn't try many times when I had mine, but my seeing conditions would not have been as good, and the mirror was a fairly standard 1/6th wave and nothing like as smooth as a Nichol I'm sure. It was excellent under most conditions but yours will pull away at high mags etc

[Piero]

Super duper, Alan!

It seems that you had a lot of fun with your 18"!  Very impressive report and a pleasure to read. Looking forward to reading your next reports on galaxies with your 18"!

[michael.h.f.wilkinson]

Great report, Alan! Very nice effort getting that split. I am sort of starting out on double stars, having bagged the Pup and a couple of others, although I am more of a galaxy hunter myself. Might start looking more seriously

[John]

Sorry I'm a bit late to this but a great report Alan

The data I have on Sigma Orionis A-B puts the separation at around 1/4 of an arc second - wow !!!!

 

[alan potts]

Yes John I totally agree with that, however it would not be the first time I have seen wrong or out of date data. I am totally sure there were two stars on show albeit for brief moments. I don't know what the 18 inch can resolve but I recall the 12 inch is stated at .33 of an arc/sec. I sort of would love someone to confirm it was indeed me seeing the split and not just a figment of an over active mind. I am going to try again tonight.

 

[michael.h.f.wilkinson]

2 minutes ago, alan potts said:

Yes John I totally agree with that, however it would not be the first time I have seen wrong or out of date data. I am totally sure there were two stars on show albeit for brief moments. I don't know what the 18 inch can resolve but I recall the 12 inch is stated at .33 of an arc/sec. I sort of would love someone to confirm it was indeed me seeing the split and not just a figment of an over active mind. I am going to try again tonight.

 

If a 12" has a limit of 0.33" the 18" should theoretically go to 0.22". Whether the seeing supports that is another matter, but in theory it could show intermittently.

[estwing]

Nice one Alan...great read and congrats on a wonderfully satisfying session....I'd shake the guys hand who recommended that mirror.....a scope that can do everything doesn't exist?...surely this comes close?....you can shave in them too you know!...clear skies.

[cotterless45]

Nice one ! Having extolled the virtues of long achros, I am increasingly swerving toward large mirror observing. If all the lights went out here, I'd be first to dive into the 16" pond !

 In the meantime , the multiples of Orion are a lovely challenge with 4". The sigma " fishhook " looking lovely.

old Nick.

[alan potts]

Ladies, gentlemen and special guests.

Just for the benifit of all site members Calvin AKA Estwing was the person that recommended that I buy a mirror made by Grasspusher AKA  John Nichol. I am more than pleased I listerned to him and I would indeed shake his hand and buy him a pint if i ever get the chance . These big quality scopes are not cheap and by no means everyones cuppa but my oh my they show you loads in dark skies, I wish I had got one years back.

Thanks Calvin

Just as an aside, it split Sirius two nights ago better than last night, I could still see the split as the star drifted to about 85% of the FOV, I only lost it over the last bit though Sirius was still sharp and to a large degree almost as pin-point as in my high quality 115mm APO, you sure cant say that of my SC scope. I am now going to try and repeat last nights split which I would not have written about normally until I double checked it, but I felt it was a bit special.

Alan

[estwing]

I'm not into doubles at all but your report is tempting me!

[niallk]

That Nichol 18"/Sumerian Canopus scope seems to be consistently performing so well from all your reports over the last year - I always read with interest   Great stuff

[alan potts]

Just taken 10 minutes, I also think Niallk that I am working from a dark site, it may well not be as dark as the very best now that lights have changed in the town a few miles away but it is pretty dam good. Just seen a beautiful shooting star with a lovely yellow colour, must have been as brights as maybe minus 5/6, best I have seen for a long time.

My scope don't like horses though.

back out, Alan

[Special K]

That horse must have bolted at the sight of them big mirrors!  Must be a little shy

That's an excellent split at .25 and a rare treat to get close to the Dawes limit on your equipment.  Nice result, and a great story to boot!  Thanks for sharing 

[alan potts]

Just a little follow up on the Sigma Orionis observation from two nights ago. I again visited the group and though the seeing was not quite as good as the first night I was able to observe a brief split between the A and B conponents using the 8mm Ethos giving a power of X286, yet again going to higher power did not help. I feel this is on the limit of everything here, seeing and scope but for me it is a fair claim of seeing the split and after a double check I am sure it was not just in my mind.

 

Saw a beautiful meteor come fire ball which came from inside the Orion area and ended due north, a lovely yellow streek which was very bright, maybe Mag minus 6 but with no sound that I could hear.

Alan

[chiltonstar]

A good one, Alan!

Interesting that you could see the split with such a low magnification (x286).

Chris