The Best Seeing Ever - Doubles and M57 - 16th May 2023

[Captain Scarlet]

I seem to have been getting a reasonable run of clear nights now we’re into Spring, a welcome change after extended periods of weathered-out months over Winter. Last night wasn’t forecast clear until the final moment, so I decided to set up just outside the garage where the scopes live, not bother with the 12” and use the 140mm refractor instead.

The SV is too heavy, at 14-15kgs fully loaded, for any but my AZ-EQ6 so that it was. I had no planned list except one I keep maintained gleaned from SGL observing reports. But I did want to give First Light to my new 2” Baader BBHS mirror diagonal and to compare it directly to its competitor in my knick-nack box, a 2” Revelation dielectric diagonal. I also wanted to look at Venus now it’s showing distinct phase and growing rapidly. Venus is currently 19 arcseconds across, and will grow to nearly 40 arcseconds before it gets swallowed by atmosphere.

I aligned on Polaris and Regulus. As soon as I saw Polaris through the Delos 10, for 94x, I sensed I was in for a good night. I’ve aligned on Polaris for possibly 80% of all my alignments ever, never tiring of little Polaris B, but the purity of the view of the pair tonight was somehow in a different league.

Venus was first, and I traded up eyepiece to the Delos 6, for 156x. I have never seen Venus so crisp and stable. Very little surrounding glare, a perfectly-defined planetary edge and lovely slightly-faded terminator. Perhaps even hints of different shades of white. I moved her just out of the field of view to check the glare, and switched diagonals to the Revelation. This diagonal gave an identical view in my opinion. I moved it just out of view and the behaviour was the same. To be fair there were wisps of very thin cloud moving across so any hints of difference in view would have been obscured by that. I understand the Baader BBHS mirror is as good as it gets, so I can only conclude the Revelation is a very good diagonal. There was one big difference however. At least one of them is not exactly 90 degrees. When switching a diagonal back in, there was a vertical displacement of whatever it was I was observing, perhaps a sixth of a degree. I suspect it’s the Revelation.

I moved on. Mars was next. Very small obviously, even at 156x so I headed for the eyepiece case to up the magnification, selecting my TOE 2.5 for 375x. Whoa! Mars suddenly became huge, dimmer and fuzzier than I’d been expecting. I suspected I might have grabbed the wrong eyepiece, went to get my headtorch and discovered I’d actually put in my Vixen HR 1.6. Even on a night such as this, nearly 600x was a little too much for Mars 😊 . Back at a correct “mere” 375x, Mars did show some hints of detail and a pole I think, but the most satisfying view was actually with the Delos 3.5, giving me 268x. I spent almost the entire night with this magnification.

But I still had no real idea just how good the seeing tonight was. I was about to find out.

First on my gleaned list was a double I’d noted down only as HR 3208, which I duly entered to the Nexus handset. When it hove into view, I recognized it immediately, a beautiful triple, one brighter component and a much closer double at a distance. All perfectly defined and separated with no visible diffraction discs, and everything still and unmoving. It was of course Tegmine. I recall having had to tease apart the close double before and could not believe how crisp this view was, essentially perfect. By now, I knew this was a rare night of near-perfect seeing. I decided this night was going to be all about supposedly challenging doubles.

19 Lyncis followed, an easy wide but attractive double.

Alkalurops, aka Mu Bootis, is another wonderful triple not dissimilar to Tegmine: a wide double where one of the components is itself a tighter double. On my notes I’d written OMG! It was absolutely textbook, once again, literally as though what I was looking at was printed on a chart. The tight double this time is more nearly aligned to the further component.

Zeta Herculis was easily split, but this was the only star of the night where diffraction rings were actually moving around a little. I was looking back directly over the middle of my house so there was some heat-shimmer involved.

Izar was again textbook, yellow and bluish.

Shifting from South to East, I headed to Delta Cygni, the first star on Cygnus’ Northern wing. I’ve not observed this before, and I awarded it on my notes with the second OMG! Stunning: it strongly reminded me of Polaris and Polaris B, except with the B dragged in right close. They were still clearly quite distinct though, just over 2 arcseconds apart. Perhaps it’s practicing to be Polaris because in about 9,000 years it will be our Pole star, due to Earth’s axis’ presession.

Normally, I’d go to Epsilon Lyrae early in a session to check the seeing. But tonight I held off knowing the seeing was great, to delay the treat. And what a treat it was. I’ve observed the Double Double perhaps tens of times. But tonight’s view of it was far and away the best I’ve had. Mesmerizing. There’s another double-double in Lyra, called Struve 2470 and Struve 2474, sometimes known as the double-double’s double. While in the vicinity, I took this in too. It’s altogether much wider-spaced than Eps Lyrae and certainly no challenge, but pretty enough. At this point I put in my Nagler 31 to give me a very wide field, going from 268x to 30x! This doppelganger now looked much more similar to Eps Lyrae, even with a similar field star off to one side. And of course, a 30x wide-field of this region of the sky is beauty itself.

I recalled from my session a couple of weeks back with the Stellarvue, I’d tried and failed to get M57 the Ring Nebula, which surprised me even though there was a Moon. In fact in my report I wrote back then:

“… decided to finish off with the Ring Nebula, M57, to see if I could see a particular dim star nearby. Well, not only could I not see that star, the Nebula itself was extremely dim, to the extent I had to use averted vision to detect it as a Polo. I’m sure I’ve seen it bright and clear in a small scope before, so I put it down to increasing foggy haze exacerbated by a 78% Moon ...”

So tonight I decided to have another go at that peripheral mag 13.1 star, apparently just off the edge of the visible ring. I went back to 268x, and saw that star immediately, it couldn’t be missed. So I thought I’d have a go for the central star instead. I stared and stared using every trick I could, averting, tapping, but no. I’d put in my TOE 2.5 for 375x, and spent in all 20-25 minutes at least trying. However, all was not lost. As mentioned, that peripheral star was obvious, as was another other dimmer star a ring’s diameter “below” the mag 13.1 star. There was also another much dimmer star coming and going “above” M57 still on the same side, and I wasn’t certain whther it was my imagination or not. So I drew a little diagram and a “?” where I seemed to think this elusive thing might be.

Looking later on SkySafari once I’d come in, the second easily seen star was the well-known (😊) GAIA 2090483595129569024, at mag 14.1 . And Skysafari confirmed that my “?” does in fact match the next “brightest” object in the vicinity, a multiple system called HL9001. Although SS suggests the brightness of this system is 13.5, that cannot be correct, as it was right on the edge on my detection, whereas mag 14.1 was plain to see and 13.1 even more so. The central star that eluded me is mag 14.8, and of course obscured within the PN itself.

On that basis, I’d estimate that my “star reach” tonight for this 140mm scope was high 14s.

I put the Nagler 31 back in to give a wide view of that Lyra region. Of course M57 was now tiny but still just about a bright ring and in a huge field of stars, lovely. Naked eye, I could see where The Coathanger was, and was curious to see how much I could get into the Nagler31’s 2.7 degree field. First I needed to know what it’s “officially” called: Collinder 399, in case you’re interested. In 2.7 degrees I could see all of it, just about! I always laugh when I see the Coathanger.

Finally, before packing up I scanned the skies around Cygnus with my binoculars and found a nice little asterism I’d not noticed before, just trailing the flying swan that is Cygnus. I immediately thought of a Christmas Tree, it was a highly triangular open cluster. This was M39 it turned out, the first Messier I’ve “discovered” with binoculars only.

What a night. Nearly everything was perfect. My views of most of what I observed will serve as my benchmarks for a long time, I expect. I took a quick sky reading just before I went to bed, it was 21.95 .

Thanks for reading, Magnus.

Edited May 17, 2023 by Captain Scarlet

[John]

Really great report Magnus - what a night !

I have used the chart (below) of M57 and vicinity below to see how faint I could go. The exact magnitudes seem to vary depending on your source. Some are actually variables of course ! With my 12 inch dob from my back yard I got to magnitude 14.7 but I've not reliably seen the central star even with that aperture. I did have some elusive glimpses at times though. I have to be able to repeat something consistently to be confident of having "got it" and I have not got there yet on the M57 central star.

Refractors can often surprise on just how well they do though - you do feel that you are getting just the best that the aperture / conditions / observer can get with that design I think 🙂

[Captain Scarlet]

Thanks John that’s a useful chart, and with 90 degree ACW rotation and L-R reflection does correspond to what I saw. Where is it from?

[John]

9 minutes ago, Captain Scarlet said:

Thanks John that’s a useful chart, and with 90 degree ACW rotation and L-R reflection does correspond to what I saw. Where is it from?

No problem but I'm afraid that I can't recall the source. I found it on the web quite a few years back and copied it into my "resources" folder. Here is a similar chart which David Knisely posted on the CN forum a few years back:

 

[Zermelo]

A great read, Magnus, thanks for sharing. Perfect seeing under 21.95 skies, "wow" indeed. There are some great doubles about at the moment.

An interesting comparison of the diagonals - I have the Revelation too, but I've read how good the BBHS is, and thought about getting one.

[MalcolmM]

Wonderful read! Great scope and great location, only slightly envious

Malcolm 

[josefk]

Another great breakfast read @Captain Scarlet - i think you would do a good turn of business offering astro bed and breakfast with tales of SQM 21.95 and steady seeing like that!

[josefk]

Thanks for posting those two charts @John lot's of their content beyond any aperture i have but interesting nonetheless. 

[Stu]

We need the WOW emoji don’t we? Fab report under what must have been amazing conditions. Not often you get near perfect seeing with near perfect darkness! Let’s hope we keep getting some clear nights, it feels great to actually have a chance to observe again, despite the lack of full darkness.

[mikeDnight]

Wow! That's a great nights observing you've had Magnus, and very encouraging too.  It must be 20 years ago, possibly longer, when I read an article in Sky & Telescope regarding a magnitude review project which I seem to remember was carried out by astronomers from Flagstaff. Before then, it was the general belief that the 13th mag star on the periphery of the ring nebula was around 11th magnitude, and that the central star was 14th magnitude. It caught my interest when I read that the researchers had during their review, found the peripheral star to be 13.2. I'd seen that star many times and found it interesting that it was easily seen through a 4" scope on a steady, transparent night. The article commented that because the star was close to the nebula, it was more obvious than it would be if it was set alone with nothing near by, and this may have given visual estimations/guesstimations the wrong impression. The estimate of 11th mag was derived from visual estimates long past, where as the Flagstaff review used photometry, so it was way more accurate. It's also interesting that you list it as 13.1 and John's charts show it to be 13.0.  Not that it matters as I'm just thrilled to be able to see it, but I wonder if there's some variability in this stars magnitude, or whether more recent observations have narrowed its magnitude down to a more precise reading? 

Anyhow, your report is awesome and I hope your good seeing becomes courageous. 

Edited May 18, 2023 by mikeDnight

[wookie1965]

What a brilliant report and a wonderful night after reading about Tegmine I really wish I had not sold my 5" I split it several times with that never in my Tal must try the celestron.

I really enjoy doubles and your report brought the night alive.

Thank you for posting 

Paul

[Epick Crom]

Hi Magnus, what a wonderful session! Double stars are mesmerising in excellent seeing conditions, sound like it was the perfect night👍

[Captain Scarlet]

1 hour ago, mikeDnight said:

… It's also interesting that you list it as 13.1 and John's charts show it to be 13.0.  Not that it matters as I'm just thrilled to be able to see it, but I wonder if there's some variability in this stars magnitude, or whether more recent observations have narrowed its magnitude down to a more precise reading? 

Thanks Mike. I did try to look up various resources including SIMBAD to find out about the magnitudes of those various stars, and where I could find anything the numbers were often different but in the same ballpark. The numbers I used when writing up were simply taken by clicking SkySafari, but for those obscure objects SS isn’t reliable I guess. Those mag 14++ stars are generally not commonly observed by we amateurs so the magnitudes supplied by databases are likely at different wavelengths and purposes from just pure visual magnitude; certainly they seem to list a few different types of magnitude all slightly different.

[Captain Scarlet]

2 hours ago, Stu said:

We need the WOW emoji don’t we? Fab report under what must have been amazing conditions. Not often you get near perfect seeing with near perfect darkness! Let’s hope we keep getting some clear nights, it feels great to actually have a chance to observe again, despite the lack of full darkness.

Thanks Stu. In some ways I wish I’d had the biggest scope I have out, the 12”, but I’m not complaining too much. It certainly lays to rest any doubts I might have had about this scope though.

[jetstream]

Excellent observing Magnus!!

The SVX140 has great transmission as well as a great figure as your observations indicate. It is under conditions like yours that the scopes ability really shines.

Rainy season here now so just intermittent observing, so please post more reports !

Gerry

 

[Froeng]

WOW