Captain Scarlet

That’s a fantastic story, well done.

I used to live in a Bortle 7/8 location, and generally used a 4”-class scope (127 Mak and 105mm frac). It was nice enough but the skies were orange soup. I live now in a much darker place, Bortle 2/3, and often the only scope I have available at short notice has a mere 5mm aperture. My naked eye. I vastly prefer the latter over the former. Cheers, Magnus

I can’t really answer the “size of the stars” query except to say that, everything else being good, the Airy Disc of a small refractor will be significantly bigger than that of, say, an 8” newt. As for the diffraction spikes, yes fishing line will certainly produce spikes, but fishing line itself might be too thin. Diffraction spikes get shorter and brighter, the thicker the obstruction. As the obstruction gets thinner, the spikes get dimmer and longer, eventually becoming non-existent at infinitesimally small thickness. It would be a case of tuning the spikes you want by trial and error. An experiment to test this out: using a metal rule or equivalent, take a picture with the rule across the aperture at full thickness, and another with the rule “side on” and compare the spikes. Cheers, Magnus

It’s described here, if you have the patience for it: https://www.telescope-optics.net/newtonian_off_axis_aberrations.htm and https://www.telescope-optics.net/newtonian_collimation.htm

I think they’re about the same, actually. The Skymax Mak has its central obstruction defined by size of the ring that secures the primary mirror to the baffle tube. It’s much bigger than the spot and baffle attached behind the corrector plate. Very naughty, actually, because the Skymaxs were (and possibly still are in the US, at least last time I looked) marketed retail on the “small CO” basis.

Sadly the skymax does not have a small obstruction. Although the central spot and baffle on the corrector are indeed small, the CO is actually defined by the retaining ring on the primary mirror, which seems to be much larger than it needs to be. Consequently the CO comes to about 33%.

What I would do is this. - collimate your scope. - point it at Polaris (bright enough and doesn’t move) - with a medium power eyepiece, deliberately mis-collimate the primary so the centre of your eyepiece view is in the “coma zone”. Also, use an eyepiece where you know where its focal plane is. - adjust the CC distance to minimize the coma. For each new trial position of the CC, you’ll likely need to reposition the eyepiece in the CC to re-focus without changing the position of the CC. At that minimum coma, note where the “new coma-corrected focal distance” is (by knowing where the eyepiece focal plane is). - (re-collimate the primary back to its original position) - if the CC doesn’t have its own distance-adjusting mechanism (like the paracorr2’s “tunable top”), it’s a bit trickier. You need to be able to adjust focus from “outside” the CC, ie not change the CC position as you focus. You could focus roughly by sliding an eyepiece in and out then fine-tune using the actual focuser (which changes the CC distance but not too much). hope that helps Cheers Magnus

Likewise the first clear night for me in weeks last night. Very early start the following morning so no scope, but I did allow myself 30-40 minutes in a chair with bins in the back field. Half a dozen perseids, quite bright, transparency very good indeed, MW really stark and detailed, I could even vaguely detect colour (brownish-yellow) in the central region. And when I went back inside, I checked the top of my car … no dew. Due to be similar tonight, fingers crossed, I’ll get my 12” out. Also M31, M32, M110, M33, M52, Airplane, Coathanger, Albireo through the 15x56s. Magnus

Thanks for the responses. I’ve opted for the moment for FreeCad. It took a while for its “logic” to click and now it seems natural: Objects / Relationships&Constraints / Degrees of Freedom etc. I tried a couple of YouTube intros but I get irritated by them so quickly, I ended up just fiddling around until things seemed to work. Cheers Magnus

For currency conversion, I used my Revolut account, which with their “premium” level allows unlimited amounts of currency conversion at close to mid-market fx rates. You can then remit directly in usd to astro-physics. Premium costs a few £ per month and you’re committed for a year iirc, but what you save in fx rate should easily outweigh that. At least, that’s what I did. (and congratulations by the way) Cheers, Magnus

Not for me they didn’t unfortunately. For my Stellarvue in February I got charged 23% for the VAT and 4.2% for the Customs, as expected. M

I am about (finally!) to embark on building my 20” dob. I bought the mirrors 2.5 years ago, and it’s languished in a box since then. I know exactly what I want made regarding the metal bits of the mirror cell, but I don’t have the machine tools to do it. However I have found a local-ish firm that can make them. But I need drawings. Can anyone recommend any easily available drawing software wherein I can draw up and send what I need to send to them? I do have an old copy of Autodesk/Autosketch somewhere in storage but so far I’ve been unable to find it amongst all the boxes. Thanks, Magnus

I too managed to observe that comet three nights ago through a 5”-ish scope. Your account describes very well my experience too. Glad to have ticked it. Cheers, Magnus

Last night the MW was on show, a good observing session was had after a long break, and I had to commemorate by getting more than just a phone pic of the occasion. So I put my 6D on a tripod, snapped 30 seconds and did a couple of seconds of phone-torch light-painting of the immediate scene. Cheers, Magnus

It’s been more than two months since I had a session worthy of a report, the last being 15th May, with my perfect-seeing night with my 140mm refractor. There was no shortage of clear nights, but a few factors combined to prevent me from getting out and setting up. The weather has been ostensibly fine but terrible for observing – so much wind! Much of May saw a continuous and strong North-East to Easterly, the only direction for which around my house I have no protected observing site. The Easterlies were followed by a lull and some very hot weather, but at mid-year I have to wait up too long before it gets dark enough. Take a look at a time zone map – you’ll see that the very West of Ireland is half way into the next-west timezone from most of the rest of the British Isles! Which means sunset and maximum darkness for me occurs 36 minutes later than, say, London, and with daylight saving on top means that “true” midnight for me happens at 0136. I just didn’t manage to stay up during June, sadly, although “loss of Astro dark” notwithstanding, even June 21st gets to mag 21.4 at that time. Then, after the wind lull, came the Westerlies, again very strong for at least a fortnight and preventing meaningful observing. Finally, last night, though it still only gets dark very late, the wind and the clouds behaved enough to tempt me out in spite of my being tired and wanting an early night. I loaded up the wheel-barrow and set up in the grassy triangle around the south side of my house. I eschewed my 12” newt, normally my staple for a night like this, and took the easier option, the Stellarvue 140. Using the Nexus DSC controlling my AZ-EQ6 on Berlebach Planet, and giving Second Light to my Baader BBHS mirror diagonal (about which more a little later) I aligned on Polaris and Altair. The night was also First Light for my new-to-me Delos 17.3 and 4.5 eyepieces, and Astronomik 1.25” UHC and Baader 2” Oiii filters. My list, gleaned from reading SGL’s observing reports, was necessarily a bit random, so I was dancing around the S-SE sky a bit. First was the so-called Struve 485, a prominent double in the OC NGC 1502 which bookmarks one end of Kemble’s Cascade. I had the Delos 17.3. A very nice OC, I have observed the double before but never “noted” it. I took the opportunity to cruise the length of the Cascade too, and possibly for the first time, having observed it many times before, I did notice the variety of colours in its stars. Exhausted, as you can imagine, at this point by my first proper observation in 2 months, I needed a break, so I quickly measured the sky. It was 23:24 and the sky measured 19.55, still quite bright for here. I’ve noted @John regularly lately regularly splitting Antares, so this was next. Sadly low down as it was, it was twinkling to my naked eye, and there was no split. To be revisited. Stephenson 1, the OC surrounding Delta Lyrae was next, and was lovely in the 1.3 degree view given by the Delos 17.3 (54x). Again, myriad star colours were quite evident. I had to refer to Sky Safari repeatedly to check that what I was looking at was what I wanted, and eventually managed to reconcile the patterns. Comet 2023 Atlas E1 featured in SGL’s reports, but lately not for a while. I decided to give it a go nonetheless, having read it was, at least before, an easy binocular object. I looked it up in SkySafari, and noting its current position a viewfinder’s width south of the star 59 Draconis, found a _barely discernible_ smudge in just the right place. I didn’t have bins with me, but I doubt I’d’ve been able to see it with them. Has anyone seen this Comet recently? Anyway, a “tick”. By now, midnight, the Milky Way was fairly clear, and my meter showed 21.15. I turned to an “old friend” on which I think I missed out completely last year, M11, the Wild Duck Cluster. At a wide 54x, it appeared as a startling concentrated bright patch of myriad tiny dots, almost globular-like in its intensity, but not at all a smudge. Trading up to the Delos 10 for 94x, its squareish shape and eponymous V-formations emerged. A real favourite of mine. My list suggested I move to 61 Cygni. describing it as a wide “red/red” double, but I must admit I didn’t get any redness. I quickly moved on to 52 Cygni, a double not unlike Polaris in relative magnitudes but much tighter. Exquisite. I’d read that this star is the “Veil star”, in that you reach this when hopping to the Veil. So that’s what I did. When I’d had my fill of the double, I widened back out to the Delos 17.3 and fitted my Oiii filter. There was the Veil, plain as day. I replaced the Oiii filter with my UHC filter, after a bit of trouble getting it out of its case – I’d forgotten it was brand new and the seal was still unbroken. I found that patch of Veil (Western IIRC) just as prominent with the UHC, brighter and less green, as you’d expect. I also had a new 2” Baader narrow-band Oiii filter, which I fitted to my Nagler 31 for a 2.7 degree FoV and 30x. I found it less satisfying than with the half-as-much FoV of the previous twice magnification. In the course of all this I had a problem with the adapter I’d been using as my 2”-to-1.25” step-down. It’s a Glatter Parallizer, which I swear by. But I found that even after supposedly tightening, a 1.25” eyepiece was wobbling around, then jammed while I tried to extract it. Most odd. The parallizer has an angled setting-screw, and when I felt around the inside surface with my finger to feel for anything wrong, there was clearly something loose, which detached and landed onto the mirror face of my BBHS diagonal. Oh no! My first thoughts were that it might be an insect (no), a piece of soil or grit that had somehow got in (no – thank God!). It turned out to be the nylon tip of the Parallizer set-screw, which over the course of its years of use had obviously cracked and fatigued off the grub-tip. I was able to gingerly retrieve it from the face of the diagonal mirror, and carried on. By now, I was done. It was half past midnight. As a final hurrah before packing up, and because the central part of the Milky Way was prominently on view, I went inside to get my Canon 6D and Samyang 24/1.4 and took a 30-second exposure of my “scope in action at night”. I measured the sky as I finished and it was 21.5 with the MW nearly directly overhead. I could hear the bats flittering around too. Not the longest or most memorable session I’ve had but a very welcome return after eight weeks off. Cheers, Magnus

This turned up on eBay a few months ago, I couldn’t resist putting in a cheeky low bid, and ended up the only bidder. I collected it from the UK just recently. It’s a ridiculously sensitive spirit level/90-degree block/V-rest. Each gradation on the bubble level is 5 seconds of arc, or 0.0014 degrees. I’ll never need that level of accuracy of course, but it is a lovely instrument. Cheers Magnus

I used to microwave one of the very big ones, sold as wet-shoe inserts, silica gel in a cotton bag. I put the microwave on to max, 800W, I forget for how long. But I then, for some idiot reason, decided to go for a run. While I was out my wife smelled smoke, went to the utility room to find a not-small fire in progress: the cotton bags had ignited. Boy was I in trouble! So, as David mentioned one post up: “do not walk away”! Magnus

Imager good god no 😁. The filters came up on eBay and I fancy doing a bit of comparative RGB star-testing so I put in a silly low bid. Nobody else bid so they became mine.

I've just returned from my UK trip to, amongst other things, retrieve all my ebay purchases over the past few months that I'd had delivered to various friends' addresses. So finally, thanks to @7sharp9, @Alan White, @bilbo , @Franklin and eBay for the following. And apologies for taking so long to acknowledge receipt. Delos 4.5, Delos 17.3, Vixen HR 2.0, Tak LE 5, BCO 10, Nikon HG 8x32, Nikon Prostaff 7s 8x42, Baader RGB. Cheers, Magnus

Head over to @jetstream’s, pretty sure he’s got a 120 he doesn’t want. You’re both in Canada so he’ll be just round the corner 😁

Lovely engaging read. Some nice targets duly stolen, TVM. I’ll bet you were wrecked on Saturday after that 🥱. Magnus

One of these came up, and I was curious. Nagler 11mm (de facto Type 1):

Gerry @jetstream already has a great (SV) 90mm, and of course the TSA120. No, he needs to fill the gaping void between his TSA120 and the 15”. Namely an SVX152T 😈

Well of course I have a 3-month-old SVX140T, which whoever has read my most recent obs report, performs to my eyes as a _superb_ scope. Its star tests also seem to match exactly Suiter’s “perfect” columns. I can also attest to its manufacturing quality, the fit and finish are flawless, and the native focuser is just like the several Diamond Steeltracks that I have on other scopes. I would have chosen an FT had it been available, but I wouldn’t be confident of ever getting one. Being as I am, far from any testing facilities and not prepared to risk taking it to the UK across a customs border, I’m unlikely to be able to have it tested any time soon. Cheers, Magnus

This just arrived, as others have mentioned it looks robust.