Merlin

I had a Prinz 3-inch/f.16 refractor on an equatorial mount in the 1970s. It was a good ‘scope and brand new from Dixon’s. I remember that both the ‘scope and its wooden box had a pleasant odour.

A traditional way to remove dew from an objective is to place a warm, absorbent, cloth inside the dew shield then cap it.

I find that the Lunt on its own isn’t as effective as the PST, but good when it’s stacked with the latter. I’ve long been aware of the problem of decontacting roughly treated etalons. In fact, I’d though of taking the Lunt to a local engineering firm to try to undo the cross-threading, but they might not fully appreciate the delicacy of etalons to shock. lubrication of the adaptor presents its own risk, as lubricants tend to end up where we don’t want them.

I have a Lunt LS50f etalon that I double-stack with the PST. I took a good image of the last Mercury transit using this arrangement. Lunt claims that it’s solar ware isn’t compatible with other systems, but it works in this case. Alas, I’ve hit a snag. I decided to attach the LS50f to a 60mm refractor, which I do occasionally, although I don’t know why I bother, seeing that the PST double-stack gives superior results. A few days ago, I was screwing the Lunt onto the adaptor for the 60mm mode, except that this time the Lunt became cross threaded with the adaptor. It wouldn’t screw forwards nor unscrew. With care, I tried a strap wrench, but that didn’t work either. Heating the adaptor could be disasterous for the LS50f. Anyone any ideas?

A point about magnification limits. For extended objects X50 max mag might apply in many cases, but for point sources such as doubles, far higher magnifications can be used. William Herschel used extremely high mags for splitting close doubles.

The best springs I’ve used were engine valve springs. Big in diameter and very powerful.

What we see in binoculars depends on the aperture and magnification.

When it’s cloudy, I go to the SDO ( Solar Dynamics Observatory ) site. Yes! there are some spectacular proms on display there today.

Anyone who might consider using a binocular mirror-mount ( no stiff neck, shakes and vibes ) and can use a saw and pistol drill, can easily make one, as I did ( three in fact! ). First-mirrors can be had from www.scientificmirrors.co.uk .

That’s a very nice image of the Orion region.

I have a 15X70 binocular, but I wouldn’t recommend that spec for a first pair. You would find them heavy and, at 15X, impossible to keep steady if handheld. I use my big binoculars attached to a homemade binocular mirror-mount. For handholding only, a 8X42 or 7X50 pair would be best. Higher magnifications than this register every heartbeat.

Musk and Co. have a Wild West attitude towards space: grab what you can, while you can. It’s free! Musk said that he would like to die on Mars. It’s certainly bleak enough. Astrophysicists are expressing a genuine concern about orbital space clutter, with regard to its effects on both optical and radio astronomy.

Years ago, I read somewhere ( possibly in the classic three volume, American, “Amateur Astronomical Telescope-Making”, that a short-focus 75mm aperture refractor captures more stars in its field than any other aperture. I can’t recall what the focal length should be.

The figure of 300 brown dwarfs in the young star cluster might have been revised since I saw an infra red image some years ago, showing the cluster peppered with the dwarfs.

The Sigma System has been likened to a miniature solar system. Infra red images of the system show it to contain over 300 brown dwarfs

It’s a problem when trying to compare different Ha ‘scopes for the reason that the quality of the etalon can vary from one ‘scope to another. I’ve heard that only about 10% of PST etalons are REALLY good. It could be the same for other makes.

I have double vision, due to a muscle having relaxed in the right eye. It’s quite severe, so I wear specs to correct for the problem. This meant that I couldn’t use some of my binocular collection because they didn’t have enough eye clearance for specs. I solved the problem by using the lenses from some of my spare specs. I removed the lenses , then sawed and filed them down so that they could be fitted and glued into the eyepiece cups. Where there’s a will ... .

There’s no denying that for many months here in the North West the weather has been very trying. There are five major weather systems that converge over the British Isles, so there are good years and bad years. The North West occupies the shear zone, where warmer air from the south battles with colder air in the North. Hence the turbulent weather conditions.

I don’t really have a “favourite” binocular, just a selection from 10x25’s to 25x70’s for different applications. In terms of quality, the very best bins I had were 7x50’s, bought in a secondhand shop for £18. The bins were of the Porro-type and in mint condition with independent eyepiece focussing. There was no maker’s name, just a serial number. I sent the number to Frank’s of Glasgow. They replied and told me I had a German naval glass. They didn’t look like military binoculars and the optics were superb.

Is it possible to use a binoviewer with PST?

I was just able to see the inner ring of HesiodusA with a four-inch refractor. The little crater looked like it had a central caldera, surrounded with an ash ring. Now it’s known that the ring was a consequence of the impact that produced the crater.

Personally,I don't like diffraction spikes and much prefer nice, sharp, star images

The East has risen .. .

Some PST's seem to be assembled in a hurry. It might just be that the etalon tuning ring isn't quite tuning to the full position. The solution to this is to unscrew the outer etalon ring to expose an inner ring that can be turned to a new ( clockwise? ) position when the screws in it are removed, then reassembled. Please do not attempt this procedure without proper instruction.

Surface detail does seem to have been in short supply, even though prominences have been, well, prominent. Maybe, as you say, the apparent dearth of disc detail has something to do with the fact that the sun is low at this time of year, or maybe it's and effect of the solar minimum that's now ending. This year I replaced the ITF ( the bottom filter above the prism box ), but with a Beloptik one not the original Meade. At first, I suspected that it might have been the new filter, but it isn't. By the way, anyone who needs to replace the ITF should consider the German filter. Oliver at Beloptik claims that it doesn't age.