michael.h.f.wilkinson

I tend to save the non-stretched version in FITS format and fiddle with curves in GIMP. APP does all processing on the linear version, which is generally the best, I find. The automatically stretched version is often rather good, so I do sometimnes save that as a jpeg to post a quick result

Nice set. The H-alpha looks a touch noisy, perhaps a bit too much sharpening. It is hard with the sun so low. I have to set the scope up across the street and do some genuine sidewalk astronomy

If you really want that longer Ethos, you could always part with your Nagler 26T5. I am sure there will be kind people forming and orderly line to take it off your hands. ME FIRST!!! ORDERLY LINE I SAID! 😜

That is near impossible to say. It all depends on the target. My Nagler 31T5 gets a lot of use, and the 22T4 is really great as well on DSOs. The latest ES 12mm 92 deg is awesome, and the brace of XW and Delos EPs are magnificent for planets.

Good result given the technique used. I would get myself a 2" to T2 threaded adapter for the telescope, add a T2 to DSLR mount adapter so you can attach your DSLR safely, and safe yourself a lot of hassle and worry about damage. They don't cost much

I spotted them too, but clouds rushed in

Very nice indeed!

As long as it's not the sun

I have had the much older GP-C8 (C8, on Vixen Great Polaris mount) for just over 25 years now, and it is an awesome allround visual scope, and cracking planetary and lunar imager. It has a maximum FOW of about 1.33 deg, which fits most DSOs. It is not and Edge-HD (didn't exist in the day), but I still get lovely views of galaxies, nebulae, most clusters, etc. An 8" Dob is just as good visually, and provides wider views, certainly, but it is not as good a planetary and lunar imager, even with motors. My C8 is also way easier to transport in a small car to carry it to dark sites, or take with me on holidays (and still fit the kids, the tent or skis, and the shoes of the missus ). It gave me breathtaking views of the 1999 eclipse in France. As said before, the C9.25 SCT will be better on planets, but it is a much heavier beast to set up, compared to the C8 (Edge-HD or otherwise). For real wide-field observing and DSO imaging, later added a small refractor (APM 80mm F/6), which is much better in that role.

No, suppose you have a 1 m focal length. Even if we focus on the moon at 384,000,000 m (give or take) the difference between that focus position and infinity focus would be 2.6 nm, or 1/200 lambda, which is well beyond the accuracy of my focuser. At 10m focal length this increases to 260 nm, which is half lambda. An object at one astronomical unit away at 10 m focal length we have a figure of 0.67 nm difference between perfect focus and infinity focus.

A "universal law" by its very definition must hold in the entire universe. Whether such laws as we have postulated are universal is another matter. However, the idea that these laws are universal is not just an assumption, it has been tested quite extensively. By observing patterns of stellar evolution through spectroscopy, and study of supernovae, we can quite confidently state that the laws of nature hold over tens, even hundreds of millions of lightyears. Stellar evolution depends on all four forces, and any small deviation in any of them would have profound implications for stellar evolution. The tiniest changes would changes things like spectral lines of the elements, the energy yield of fusion, the gravitational pressure in the centre of stars as a function of stellar mass, or the mass at which white dwarfs get fed up and explode. As for me, as of November 1, I am joining the hunt for particles that might explain dark matter, by helping in the development of new algorithms for detection of gamma ray events using the Cherenkov Telescope Array (under construction).

A fast telephoto is indeed nice, and even an EQ3-2 mount will get you decent results. I used a Sigma 50-100mm F/1.8 zoom to good effect on comet NEOWISE this year A 200 mm F/2.8 L also worked nicely: And it also does several larger DSOs well:

If your APM eyepiece is this one: https://www.apm-telescopes.de/en/optical-accessories/eyepieces/reticle--astrometric-eyepieces/apm-reticle-eyepiece-20-mm-70-1.25.html it is possible to get the reticle in sharp focus by twisting the rubber ring. I have a similar one, which worked fine, until I replaced it by a home-made solution

I have both. The ASI174MM works best in my H-alpha rig, which works at F/25 or so, so the large pixels of the ASI174MM are just about the right size. The ASI178MM has smaller pixels, and works better at F/12 or thereabouts. This is fine for my 80mm F/6 for full disk, and for detail at F/12 with a 2x TeleXtender. The Solar Scout is F/15.5, so you either need a bit of focal reduction with the ASI178MM (or live with the oversampling), or you need to add a 1.5x Barlow for the ASI174MM. The ASI290MM has slightly larger pixels than the ASI178MM, but is rather smaller in surface area. The ASI1600MM is near perfect in terms of pixel size vs focal ratio, but is rather expensive. I am not sure how large the image circle of the Solar Scout is in mm.

Hadnt spotted this. Fingers crossed for some clear skies so I can bag another nova

Made two more versions quickly. Basically took the pixel-wise average of the two previous JPEG versions, and fiddled a little bit with curves in GIMP Upping the saturation got me this Should really do this in 16-bit TIFF (might do that this evening)

I got some odd results in APP. Just removing gradients and its default automatic stretch give this: This has a similar yellow cast in the stars, perhaps a bit less. If I calibrate star colours, I get this: In which the stars may be better, but the galaxy is rather too blue. Might want to fiddle around a bit more later

Definitely beter. If you could share the unstretched FITS or TIFF I could have a bash in APP, if you like, just to see what it does

I think I paid through PayPal. You can always use the free trial to see how it works.

Nice detail in that shot. The stars and core do seem to have a bit of a yellow cast. I find that gradient removal and star/background calibration in APP work pretty well. Maybe worth a shot

The Bird-Jones design is not bad per se, but I have yet to see a good incarnation in the wild. I have heard Vixen made a decent one in the past. If you go for a 114 mm Newton, I would opt for the 900 mm focal length, at 500mm they often come with a spherical mirror: fine for wide field, but much less for planets. If you can stretch to a 6" F/8 Dobson, that will give you much better planetary views

Very interesting. It is particularly odd that parts seem to be shrinking, not just fading

The small pixels might find their use in RASAs

Really nice stuff. What scope and camera did you use?

Very nice indeed.