ollypenrice

The curve on a Schmidt plate is interesting. Bernhard Schmidt, who blew off his arm as a child chemistry experimenter, claimed that he could get comatose drunk, pass out for a long time and then come round with the solution he'd been looking for. He had conceived of the curve required in principle on a lens to reduce coma on a reflector but it was, apparently, impossible to grind. Then, perhaps after one of his bibulous escapades, he went and asked Walter Baader about the physics that would apply to the distortion of a glass blank if it were placed over the top of a cylinder from which the air could be evacuated. Baader (one of the few people whom Schmidt liked) said he didn't know but pointed him to the right book. Schmidt's hunch proved to be correct: if you put the blank over the top of a cyclinder, paritally evacuate the air beneath it and then grind the vacuum-distorted blank flat again, it will, when released, have the desired shape. This is still how they are made. Since the primary of an SCT is spherical and the corrector can be made in this relatively simple way, they are an attractive commercial proposition. Olly

You certainly can, dear boy, and may I return the compliment with a full brillig of slithy toves and the hope that the new year will see you gyring and gimbling in the borogroves whatever the mome raths think of it? lly

Super project - and successful. Olly

That's coming together very nicely. Yves Van Den Broek shot a vast mosaic also including the NAN but heading the other way, up to include IC1396. The large scale structures are fascinating throughout this region. Great stuff. Olly

Yes, just add more because this is nice and clean. Olly

Lovely. The Taddies are so much better in a mixed NB palette than in broadband. Olly

Punchy rendition! Olly

Thanks Phil. That looks like a very convincing solution. I'll put it to the team! Olly

It doesn't take much with a RASA!!! Olly

It's a grey smudge which can make your spine tingle, though... Olly

If a requirement is to cover the whole galaxy you'd need to go considerably deeper, because much of its full extent is very faint. I dare say that this is why the publishers don't really want this record on their hands: it is too ambiguous. In the image below, you can see that both ends of the galaxy reach out far beyond what we may think of as M31 but, even here, there will surely be more. There seems to be an interesting region of faint nebulosity, not in the plane of the main disk, on the right hand end. Olly

I totally agree with Michael. A smaller number of better eyepieces beats a larger number of more rudimentary ones. In my main visual scope I have just two eyepieces. Yes, I'd like a third but the one I'd like is about 500 dollars so it will have to wait for a moment of folly! It is also better to concentrate on looking rather than finesse about which EP to use. Olly

Be reasonable, Vlaiv! Where is your Christmas spirit? I'll offer you £25 and pay half the postage. Yes! 🤣lly

How did I guess that some serious binning was at the back of Vlaiv's mind???? But he might have a point. Olly

Sound! Olly

God knows, we all love the challenge! 🤣 Good for you. Olly

Gosh, that's remarkably good. Olly

As Peter says, above, a Newtonian is an inexpensive choice and will trounce an achromatic refractor for imaging. An achromat really is not a good option. Olly

The RASA choice involves a bit more fiddling at setup but, once you're running, it is phenomenally fast. Ours goes very deep on faint targets in three hours, which is astonishing. Olly

I guess we're looking at different things. I'm concentrating on the filamentary structures, the curved lines roughly radial within the galaxy/ Olly

Yes. You could also drill three indentations into the blocks rather than use paint. Olly

Exactly. I'd get pretty sick of the Sahara Desert if I had to live in it but that doesn't mean I don't want to see it! Olly

I think the one processed via BlurX is perceptibly better. What is it that you don't like? Olly

Brilliant. I've also thought about this but never done anything about it. My thinking went along simpler (ie cruder) but bulkier lines - a wooden Dobsonion binocular chair. Olly

Here are two linear images. 21x15 minutes at 0.9"PP using TEC140 with Atik 460. At 0.9"PP this is slightly oversampled but not absurdly so. Both have been through DBE but nothing else. Lum21X15 les granges M51 has had no further processing while Lum BXT has been through Blur Xterminator set to a high degree of non-stellar sharpening and automatic PSF. Obviously an adjustment of BlurXterminator could have reduced its effects but I worked with this version. https://www.dropbox.com/scl/fo/5r7omurjdyaxth83dwz5r/h?dl=0&rlkey=294dwqgyw44kultgl1c3n7ec7 https://www.dropbox.com/s/en9bov5uxq9igtz/LUM BXT.tif?dl=0 I think these links will give access but Dropbox seems to change on a regular basis and leaves me baffled. If they don't work for you, please PM me a reguar email address and I'll send them to that. My own final version is in the link below. I did not push large scale contrasts as hard as I might have done because I was looking fr a result which was precise but gentle. I've already enthused about BlurX on here so I leave you to try the data and see how you feel about it. https://ollypenrice.smugmug.com/Other/Galaxies/i-d5BBZQp/A Olly