Captain Scarlet

Forecast-only-at-last-minute clear night last night, and near-perfect seeing. The best seeing I’ve ever experienced. I had the SV140 out and slew a whole host of doubles, but the main result was how deep I was able to go on the stars around M57 Ring. The nearby mag13.1 was plain to see, a little further down the 14.1 was also easy, and I drew a”?” on my notes to question whether there was another faint object coming and going. Turns out there was, HL9001 apparently, clearly dimmer than the 14.1 so I guess I was seeing down to 14.5. Central star eluded me though, at 14.8 and obscured of course.

Full report of my best ever seeing to come later, a magical night.

Cheers, Magnus

Very nice Joe. I too am envious of your SH access. How far do you have to go to get to a dark site? Do you do that?

Cheers Magnus

It really works well, totally exceeded my expectations. And yes the FF does add back focus I think, I’ll try it without and see, but anyway without the FF the curvature is _severe_, intolerable actually.

The choice of Pan 24 is very lucky. It’s the only one of all my eyepieces that can reach focus, because the nosepiece is really short. I looked at the TV site eyepiece specs, and the Pan24 has the shortest of their entire eyepiece range. I might try to get a metalshop to professionally take 10mm out of the middle of the main tube (everything unscrews cleanly) and splice it back together to give me more options.

M

Our first summer-like day this year saw daytime temperatures reach 19 degrees, and a forecast for a clear and still night, though I was concerned about rising currents as the evening cooled. Seeing was indeed somewhat poor to begin with, a combination of cooling air and likely a cooling scope too, as my new tactic to fend off dew involves bringing the actual scope out at the last minute, and simply tolerate the first few tens of minutes as the mirror cools. I spend that time collimating and lining-up finders, anyway.

Speaking of finders, tonight was First Light for my new super-finder-deluxe, the SW Evoguide 50ED, with FF, Baader T-2 prism diagonal and Panoptic 24, making it a 10x50 finder every bit as good optically as my Leica 10x50 binoculars. I found (!) the Finder very nice indeed, not only a finder but every bit a supplementary co-aligned wide-field scope too.

Collimation hadn’t shifted at all since my last session, and I aligned for the first time on Vega and Algieba (I did have to align again later, see below). I was using my Nexus DSC, and not having planned any sort of list I decided to start off with some satisfying easy targets, and then use the Nexus DSC “Tour” feature to find all PNs, CGCSs and NGCs within 7 degrees of a chosen centre point.

First target, mainly to check the seeing, was Epsilon Lyrae. With the alignment- DeLite 18.2 still in for 100x, I could not split the two doubles, they were two bits of mushy mess. I swapped in my Ethos 13 for 141x and yes I could now split them, but far from the best view I’ve had. Cooling ground and cooling scope, I guess. I moved on to the Leo Triplet, M65 and M66, easily seen through both the 12” and the finder. The third galaxy, NGC 3628, was distinct in the 12’ of course, but not so in the finder.

I headed across to Hercules to M13. The seeing seemed to be better at the slightly higher elevation (in fact it got better the whole night) and M13 was as ever entrancing, the Propeller quite easy tonight. M92 was similarly splendid. I’ve not observed M57 Ring Nebula for a while, indeed I couldn’t even see it some nights previously through my SV140, Moon and haze prevented it I think, so to see it as such a pronounced Polo tonight was gratifying. However, looking through my 10x scope, it wasn’t at all obvious which of the myriad white points was M57, though I was confident it was definitely in there somewhere. I suddenly remembered I now have a whole drawer-full of hardly-used filters, so I “popeye’d” my observing eye and went inside to retrieve my Oiii filters.

The 7-degree FoV through my finder was, pre-filter, a blaze of lovely stars, one of which was M57. Simply sticking the filter between my eye and the eyepiece, all the dimmer stars disappeared, except one! M57 was left clearly standing out on its own just where it should be, between Sheliak and Sulafat (Beta & Gamma Lyrae). So, what @Stu suggested might be one of the more difficult Messiers to catch through 10x50s, was easily seen through this, er, 10x50 monocular. But being so small, one needs to know which bright spot it is.

I went for M82, and stared at plenty of detail especially the diagonal dust-gap in the middle, moving along a little for a quick look at M81. Finally from my intended “all-stars” list I went for M51, near zenith it should have been spectacular. Unfortunately, because my deluxe finder is rather heavy, with usually only my SkySurfer V attached (which was also on the scope tonight too), I’d had to shift the whole tube further back in its rings to keep closer to balance. I knew at the time I set up that zenith-objects might be a risk. And so it proved: as the tube approached zenith and rotated around the RA-Az axis, we had Tripod-Strike!, followed by a hideous-sounding screech from inside my mount. Immediate switch-off, re-level, re-align and thankfully all good, phew! M51 would have to wait for another day.

Using Nexus DSC’s Tour feature, I chose a 7-degree field around Alphecca, Alpha Corona Borealis, as my “area”, and set my catalogues to show PNs, CGCSs (carbon stars) and NGCs (likely to be dominated by faint Corona Borealis and Hercules galaxies). I listed the objects I managed to see, and the first ones all seemed to be mag 12-14,5 galaxies: NGCs 5958, 6001, 5961, 5974, 6020, 6008, 6027, 6064. They were all faint, mostly right on the edge of averted-vision detection, and through this I learned that my galaxy-limiting magnitude was slightly over mag 14. Some supposedly brighter ones actually eluded me. I noted these and when looked up they tended to be face-on galaxies of low surface brightness, like much dimmer versions of M33 or M101. Nonetheless, it was nice to see galaxy after galaxy in close proximity. Oh for my 20” to be ready when I’ll be able to see the field of them.

Eventually, my list directed me to a non-galaxy, in the form of CGCS 3679 and later CGCS 4038. “CGCS” stands for Catalogue of Galactic Carbon Stars. Both these stars were noticeably and highly orange, and I must dedicate a future session to this category alone. Also, M56 appeared in the list, a first for me and a small globular. I checked if I could see it in my finder, yes there it was. I had been hoping for more PNs, I was really just trying pot luck on my area and I guess there aren’t many in this region. One that did pop up though was something my Nexus called “Turtle Nebula”, aka NGC 6210. As I looked through at the field of objects, there was one quite bright thing slightly more “blobby” than the neighbouring stars, so I attached my Oiii filter to the Ethos 13, and my goodness, the PN, for that was undoubtedly what it was, leapt out! Very nice.

For scope-play, that was it for the night. As I packed up, I noticed a streak of pale cloud appearing from the East, then slapped my head. It was the Milky Way, really quite prominent and parallel to the horizon. On one packing-up trip I grabbed my EOS6D and Samyang 14/2.8 and took the above 30-second exposure (non-tracked), painting my observing area briefly with my head-torch in white. As the picture shows, it’s nice to see the central part of our galaxy coming into view, and the complexity really was evident naked eye. My SQM-L showed 21.83 at zenith. It was also nice to see Antares again and the highly distinctive shape of Scorpius appearing.

A meteor streaking right from Lyra gave me my final Hurrah! Of the session.

Finally, I confirmed from a separate thread I started a few days ago, that most if not all the Messiers are detectable through 10x50. Certainly all mine were this night. Although it helped that the 10x50 in question was directed by a Nexus DSC and fixed to the OTA.

Thanks for reading, Magnus.

Last night, a wonderful clear night just before I packed up around 1:30am.

Just come in from a decent session with the 12”. Did a few usual suspects then a tour of NGCs mostly faint galaxies and some PNs a few degrees around Alphecca (Coma). Also first light for my Evoguide 50 deluxe finder which worked beautifully. Full report a more adventurous session-photo to follow tomorrow I hope.

Just winding down with a Franziskaner.

Magnus

1 hour ago, Stu said:

There is a funny story behind that. I’ll let my FB post do the explaining. I still haven’t got it back!!

They’re passive-aggressively enforcing no-mow-May on you. Insects are grateful 🐝 😁

M

7 hours ago, Dave scutt said:

There's seems to be a lack of clubs around my area the closest is Galway,  you would think there would be one in Mayo as it's bortle 1 and a dark site

Sounds as if you should do what I’m attempting to do … start one. To begin with you’ll be Founder, President, Treasurer, Secretary, only member 😂.

My approach has been think of a name, get a little bit of infrastructure set up, i.e. a website and/or FB simply saying what it is and where and when you’ll meet up (perhaps a local pub with observing lawn out back, last Thursday each month say), distribute some flyers and tell anyone who’ll listen, turn up and accept the first couple of “meets” you’ll likely be the only person there. You may be surprised who comes out of the woodwork.

Cheers, Magnus

Thank you all, that’s great, just what I need. What will go into my article will be the word “most”, as it’s for the benefit of people who share these skies here. For myself, I can easily see M1 in my 10x50s.

Thanks, Magnus

I've been asked to write an astro piece for our local community newsletter, and one thing I want to touch on is equipment for prospective beginners. Binoculars are one obvious recommendation, so my question to experienced dark-sky observers is this: "Approximately what percentage of Messier objects do you reckon are detectable with 10x50s at a dark site?" Our skies here are 21.8, and I have measured 22.0 a few times with the MW out of the way on tryly transparent nights)?. I have a feel for what the answer might be, but I have by no means seen them all.

Thanks., Magnus

PS I'm also starting up an astronomy group/club/society - there are none here.

8 minutes ago, yelsac said:

Interesting so a small amount of movement isn't a problem. I'm used to an old skywatcher mirror cell where the mirror was held firm no movement.

I suppose I was just concerned about collimating the scope. I really enjoy planetary imaging where collimation is important.

With the movement, every time you slewed your mount to another target or had to do a meridian flip you'd have to constantly re-collimate.

I would expect the effect on collimation of that tiny amount of lateral movement will be completely negligible, especially compared with the astigmatism you’d have from tight grubscrews.

M

44 minutes ago, yelsac said:

Interesting Magnus, so may I ask when you fitted the new cell to your 300mm mirror was your mirror tight to the clips or did it move around?

I noticed there is nylon screws through my clips that could be tightened up to the mirror to stop any horizontal movement.

Those nylon grubscrews are there to constrain the mirror's side-to-side movement (using nylon rather than the metal of the clips themselves), but not tightly constrain. They must not be tight to the mirror's edge, they must be infinitessimally clear of the mirror, so the mirror is constrained, but not put under any pressure (even a little pressure causes astigmatism - my brother-in-law once asked me "why are the stars triangular?" when I'd made that mistake). What I do now is screw those nylon grubs in until they just touch the mirror, then unscrew about 1/8 turn. You may be able to feel a very small amount of "rock" as the mirror shifts when, say, you're carrying the tube out to the mount - that slight amount of movement is fine.

1 hour ago, yelsac said:

 

Appreciate the advice.

It's a fairly recent scope with their 9 point mirror cell, the mirror was kept in a shed & is rather grubby.

The silicone doesn't seem to be stuck anymore although it's still there, the mirror is loose in the cell, I can actually move it by hand from side to side.

Not sure whether to re-silicone it or put some rubber shims in to secure it a little better.

The whole point of the cell design is that the whiffle-trees (the three triangles each containing 3 nylon supports) have freedom of movement. The silicone prevents this and is unnecessary, indeed destructive to the whole purpose of a cell.

I bought my 300mm cell a few weeks ago new from OO. There was no silicone, quite rightly. I bought my 200mm within a VX8, and the whole cell was slathered in silicone, top, back and sides. And whoever did it made a real mess. I dismantled it and removed all the silicone and it now behaves as it should. Aside from the difficulty getting the mirror out to clean, the cell is IMO a good design. Why they feel the need to silicone everything up I have no idea.

Magnus

2 hours ago, yelsac said:

Hi

Anyone had any experience with taking out an Orion optics reflector mirror? The cell is one quite different from a skywatcher.

I want to remove the mirror on my oo vx scope to clean it.

I've removed the mirror cell from the tube, do I have to first unscrew the collimating bolts all the way out & take off the section with the fan to be able to get to the bottom of the mirror clips to undo them?

Just checking as I don't want to ruin anything. If anyone has any pictures of the process that would be great to.

Thanks

 

Yes I've done this a few times now with both my OO mirrors. I did consider cleaning them whilst still in cell, but decided in the end to completely remove it.

Unfortunately yes you do need to completely remove the rear section by removing the collimation knobs. You then need to unbolt and remove one of the "clip units" (two bolts and possibly a grubscrew. With one clip unit removed, you can then remove the mirror "sideways". It needs great care, of course.

Magnus

Edit: I plan at some stage to grind away  the top part of the mirror-retaining clips and replace with a more removable or rotatable pin arrangement, so that I can simply lift the mirror off vertically. I haven't designed it yet, but it shouldn't be too difficult.

Absolutely amazing. I remember your much earlier shots from a year or three back, themselves very good indeed, but my god you’ve kept learning and your stuff has become something else! Keep it up.

Cheers Magnus

Paul so pleased for you to see that sort of detail in M51 and 81/2. If you could see spiral structure in M51 you should easily have been able to see the third part of the Leo Triplet. Is it possible you panned in the wrong direction from M65 & 66? I have done that before more than once.

Having myself seen M51 from a dark place, I subsequently found myself able to see it from London albeit as a faint smudge, by knowing exactly what to look for and where to look relative to the two bottom “saucepan handle” stars of the plough.

I did feel your joy from your report.

Cheers, Magnus

Yes the change was certainly worth it. The Planet is far more stable and solid than the SW 2” tripod. As for tripod-strike, these pictures show that it’s not a problem for me, with my previous 300p, my current 300/carbon-tube, and my Stellarvue SVX140T. Though I did consider the extension pillar, so far it’s (just) not been necessary:

From the floor to the top of the head mine is 87cm, and 74cm between two the tips of the rubber feet. You’ll see from my photo that it’s not fully folded in, but I’ve adjusted my figures as if they were.

Cheers Magnus

10 hours ago, Mr Spock said:

Here we go again. BBC says clear sky and... it's absolutely pouring down!

Yes just the same here actually this am

Just looking at Plato … I can get a few craterlets, what do you think?

Duplicate post

2 hours ago, JeremyS said:

Be interesting to see how it takes magnification.

At the moment I’m unable to tell. Because of the very short eyepiece adapter, the eyepiece sits on the internal lip which prevents the nosepiece sitting atop the prism face. So it turns out that the critical dimension is the distance from the open end of the nosepiece to the eyepiece focal plane. As it happens, the Pan 24 has a very short nosepiece*. Those on all my other eyepieces, every one, are significantly longer. It’s lucky the one I really need to work, does so. But it does give me an excuse to take 10mm out of the middle of the tube at some stage.

M
 

* edit: the shortest of the whole TV range, it turns out, lucky coincidence for my 10x50.

Just under a year ago, I picked up an Evoguide 50ED, intending to use it as a super-luxury finder to go one better than the APM 50mm finder I already have, itself no slouch! It would mean that I could dedicate each to a scope and avoid too much re-alignment fiddling. Assigning the APM to my 200mm newt and the Evoguide to my 300mm newt. In theory, with my 24mm Panoptic, I'd get a 68-degree 10x50 finder.

Of course, I knew in advance that this scope is designed as a guidescope not a finder, and it comes with warnings that it will not reach focus with a diagonal attached. This didn't deter me. If necessary and in extremis I could perform some surgery on the main aluminium tube and shorten it, though that would be saved as a last resort.

Initially, I removed the green helical-focus unit and simply shoved a spare generic 2-inch SW star diagonal up the tube, taping it in place. I added my 24mm Panoptic. To my surprise, in daylight I did appear to be able to reach focus JUST ABOUT, but there were four problems:

1. it was UGLY, with a 2" lump jammed in to one end;

2. I had no convenient focus control, as I'd removed the helical unit;

3. Something I had not anticipated: severe, really severe, field curvature. A 16km-distant target (effectively infinity for a 242mm FL scope) at centre-field was lovely, easily the match of, say, my Leica 10x50 Ultravid binoculars. At the edge of the field, it was extremely blurry. If I re-focused to bring the edge into focus - crudely, by simply manually lifting the eyepiece out a bit - the edge became superb too, ruling out edge-aberration.

4. I only discovered this later using the Ugly Ducking on the night sky: it hadn't really come to focus during the day: my eye was highly stopped down, of course, being daylight, and I had obviously accommodated a bit - something I'm less able to do with my pupil fully dilated at night.

I'd been following @markse68's very similar project, and seen that two modifications could solve all the problems.

i. Baader T-2 prism diagonal, to screw directly onto the back of the OTA;

ii. Starizona Field Flattener, made specifically for this scope, which also increased total available back-focus to 55mm, AND of course does what it says: flattens the field.

The new diagonal and its low-profile eyepiece adapter arrived yesterday, I assembled it all and have just daylight-tested it. So far I couldn't be happier. I can achieve focus with an extra 5mm to spare. The field is now truly flat, an amazing difference, actually. Most importantly of course, it now looks the business. I can't wait to get it under the stars, and combine my 1830mm 300mm scope with a mega-wide-field well-corrected 242mm alongside.

Cheers, Magnus

Two diagonals and an adapter. Dare I say it but sat next to the BBHS 2” mirror diagonal, the T-2 looks “cute”.

The small diagonal plus adapter are the final bits for my SW EvoGuide 50 to make it into a luxury finder.

And see what passes for delivery around here - some of them can’t be bothered to go up my lane. It was pouring with rain and luckily I saw the van down the road from the house.

Magnus

6 minutes ago, kbrown said:

I might be wrong but I thought that 3 (straight) vanes would produce 6 spikes since they're all pointing at different directions?

Yes that’s true, but all told less diffraction though. A 4-vane spider in fact produces 8 spikes, but in 4 pairs which overlap/“double-up”. With a planet, for any given point on it the total amount of vane-induced-diffraction-softening from that point’s neighbouring “pixels” is reduced both by the one fewer vane and the fact of thinner vanes.

I’ll probably start off by adding one vane with the original spider still in place, to compare spikes side by side