What a mirror

[alan potts]

56 minutes ago, chiltonstar said:

A good one, Alan!

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

Chris

Chris,

I personally feel that seeing any split is about cleaness of the image your looking at, I can sometimes see Sirius under X100, I believe purely due to sharpness or the star. I think when like last night I tried the 6mm at X380ish and the 4.5mm at X508 all it did was introduce more seeing related issues into the picture which did not benifit anything. In this scope here at X286 stars are still fairly sharp and easier to focus, that cannot really be said for close to X400 and above. I am sure if I were to cart the scope to somewhere like Namibia where the skies are black and very dry these limits would go up somewhat, as it is we here in sunny Bulgaria have seeing issues but maybe not as bad as England all the time.

BTW I use the word split in the loosest possible sense of the word, maybe more accurate would be to say I could see two separate points of light and the strong suggestion of a gap.

Alan

[chiltonstar]

1 hour ago, alan potts said:

Chris,

I personally feel that seeing any split is about cleaness of the image your looking at, I can sometimes see Sirius under X100, I believe purely due to sharpness or the star. I think when like last night I tried the 6mm at X380ish and the 4.5mm at X508 all it did was introduce more seeing related issues into the picture which did not benifit anything. In this scope here at X286 stars are still fairly sharp and easier to focus, that cannot really be said for close to X400 and above. I am sure if I were to cart the scope to somewhere like Namibia where the skies are black and very dry these limits would go up somewhat, as it is we here in sunny Bulgaria have seeing issues but maybe not as bad as England all the time.

BTW I use the word split in the loosest possible sense of the word, maybe more accurate would be to say I could see two separate points of light and the strong suggestion of a gap.

Alan

Agreed - split is always about "cleanness of the image" (seeing + focus + optics); for me, my best view of Sirius B has been with x70 to x100.

You must have excellent visual acuity, as I need about x300 for a 0.7 arcsec split (you are a youngster though of course!).

Next time I get a clear view of Orion, I'll have a look with my 180 Mak which should theoretically show an elongation, but not of course a split.

Chris

[alan potts]

It looks set clear for tonight as well so maybe I will get mine out for the first time in months. Sadly since the Sumerian came along it sees little in the way of action which is a dam shame, good scope once that stupid visual back is changed for something better.

Alan

[chiltonstar]

4 minutes ago, alan potts said:

It looks set clear for tonight as well so maybe I will get mine out for the first time in months. Sadly since the Sumerian came along it sees little in the way of action which is a dam shame, good scope once that stupid visual back is changed for something better.

Alan

Mine came with a more recent back perhaps (6 months ago), with a 2" diagonal and no obvious image shift when focussing. With a 2" 38mm Panaview, it covers the Leo Triplet, or M81+M82 nicely, with a bit to spare, so the real FoV must be about 1 degree.

Chris

[bish]

Nice report. I've not paid too much attention to doubles in the past, but have just ordered the Cambridge double star atlas. I started on variables a few years back as my back garden is very limiting for DSO's. Variables and doubles gives me whole new list for when I can't make it to a dark sky to look for galaxies and nebula

[alan potts]

Chris,

You were lucky then I have had mine from about 3 years back and the affair that it was fitted with could not have been more cheap and nasty, I then had to pay 36 quid for a thread adaptor which is crazy and I used my Meade visual SC back. The other was consigned to the bin. No good for me but at least they did something about it.

Bish,

You will like the Cambridge Doubles, I have it, it makes their normal atlas look very wanting.

Alan

[scarp15]

Very interesting and informative read and quite an agreeable challenge. Though looks like the Night mare will have to wait until next season.

[alan potts]

Yes the Horse is getting lower for me now though I do get dark a bit earlier than the UK and it is higher in the sky. I have tried so hard for it this year but now I can live without it, never liked horse's after one kicked me years ago.

Chris,

I had a go with the 180mm Mak in nothing better than average seeing. At X270 with the 10mm Ethos there was no indication of any mis-shape of the "A" star but as I say it was not clean in any way shape or form, worth a try from your end if you get the chance.

Alan

[chiltonstar]

1 hour ago, alan potts said:

Yes the Horse is getting lower for me now though I do get dark a bit earlier than the UK and it is higher in the sky. I have tried so hard for it this year but now I can live without it, never liked horse's after one kicked me years ago.

Chris,

I had a go with the 180mm Mak in nothing better than average seeing. At X270 with the 10mm Ethos there was no indication of any mis-shape of the "A" star but as I say it was not clean in any way shape or form, worth a try from your end if you get the chance.

Alan

Alan,

I had a try last night as the seeing was excellent, and I had a window of an hour or so on Orion before it dived into a pine tree.

I started on Sirius B in twilight - very clear, and as the scope cooled, the Pup sharpened to a very clear point.

Turning to Sigma Orionis as I knew the seeing was excellent by then, AB, D and E were as usual a beautiful sight, with C visible easily at lower mags (<225). AB was definitely not round, more like an oval at x300. However, I could see a bright point to the S of it (PA say 160 - 180) about 2 arcsec away from the oval AB. It looked stellar to me (a field star perhaps??) but could have been a visual artefact, for example caused by overlap of two sets of close diffraction rings, which I have seen before in my fracs. Definitely not Sigma Ori G, which has a PA of about 20.  It would be interesting to know what others see??

Chris

[alan potts]

Chris,

I think that may be diffraction rings as you said, I notice that the Mak design tends to have more obvious ones than say an SC or Mak/Newt scope. The other night as I was basically playing about, I put Sirius very close to the edge of an Ethos, 17mm I think, it produced a very pretty eliptical halo, a bit like the rings around Saturn. With the scope being driven 95% of the time I always view things in the centre and of course have never seen it before.

Going back to your question, I never saw any field stars near to the group.

Alan

[chiltonstar]

17 hours ago, alan potts said:

Chris,

I think that may be diffraction rings as you said, I notice that the Mak design tends to have more obvious ones than say an SC or Mak/Newt scope. The other night as I was basically playing about, I put Sirius very close to the edge of an Ethos, 17mm I think, it produced a very pretty eliptical halo, a bit like the rings around Saturn. With the scope being driven 95% of the time I always view things in the centre and of course have never seen it before.

Going back to your question, I never saw any field stars near to the group.

Alan

I think like all scopes with central obstructions, Maks have more obvious diffraction rings than fracs. As the view they give is quite "frac-like", the rings and Airy disks are more obvious than on some obstructed telescope designs which give a much "softer" view.

I don't know about the other star/artefact: I had a good look yesterday and found some sketches and images on the web with a star in pretty much the same place.

Chris

[alan potts]

Chris,

I will have another look at it next time out as when I had the 18 inch on it I would have thought it would have been pretty obvious and I don't recall anything. It could of course be just a case I was looking at the AB component too closely to notice much else.

Alan

[chiltonstar]

Another one worth a look with your mega scope Alan is Zeta Bootis. it's also fairly close (0.4 arcsec) and is in a good place at the moment. As the seeing last night was close to excellent (4.5/5) I had a look with my 180 Mak to see if I could see any elongation. In fact, at x340, it was clearly elongated and at x540 (the highest I've taken the scope yet), it was a clear waist-ed peanut, with a beautifully stable diff ring structure. With your scope, I imagine you should split it into two clear Airy disks - maybe you've tried already?

Chris

[alan potts]

Chris,

It may well be in a good place for you at the moment but not so for me. Where I set up the house is in the way and to move would mean planting the scope on my freshly sown lawn which will not do either the lawn or scope much good. I also have a very large walnut tree over that way too, after midnight would be fine but with being up every morning at 05.30, 12.00 is out of the question. I had a look at Sigma Orionis with the 190mm Mak/Newt and I agree with you it was elongated though I only went to X285 with the 3.5mm Delos. Without a doubt I could see it though.

I feel I making my own poor seeing at the moment with having to water the new grass almost every night, with having daytime temperature of 32 degree you do sort of get a steambath feel about things and sadly I planted rather a lot maybe 500m2, still lets hope it will look nice when it grows.

I will try it later in the year.

Alan

[chiltonstar]

I envy you the walnut tree and the 32 C temperature!

Chris

[alan potts]

5 hours ago, chiltonstar said:

I envy you the walnut tree and the 32 C temperature!

Chris

Chris,

It's been up and down but also has been strangley hot for April on many days, due to go very cold from Wednesday, just as I have put the warm gear away until later in the year.