ollypenrice

Nice when this happens. Olly

Not exactly. The scope carrying part of the mount is driven by a worm gear driving a wheel gear and these can have too much free play in them, meaning the driven part can oscillate relative to the driving part. What tends to happen is that the scope spends some time resting on one side of the backlash then flops across to the other side. In each position it will produce a stellar image., like OO , each O being a stellar image. As it flops between positions it will also create a bridge of light between them. 0-0. By running east heavy you can encourage it to rest on one side of the backlash so creating only one of the two stellar images. Olly

The Dec motor is active in autoguiding since it is used to correct errors in Dec. These occur even in a perfectly accurate mount, perfectly polar aligned. (The apparent position of stars moves with atmospheric diffraction as the altitude of the object varies.) The dec axis can also introduce errors by having backlash. Backlash can also affect the RA axis and can be made worse by perfect balance. It is best to be heavy on the east so that the imbalance leaves the payload resting on the pushing side of the mesh. Dec backlash can be addressed by deliberately small polar misalignment and the disabling of the guiding direction not needed to correct this error. (Obviously it is best to correct the mount mechanically, however.) The focuser is another popular cause of image shift and the hardware holding the gear into the drawtube is another. Screw fit beats push-and-locknut. Exceptionally, chips can also be lose in cameras. My own hunch is that you have more than one source of backlash but mostly RA. The most important thing to do is identify the RA and Dec axes on the trailed images. Could you post a star trailed image with the axes identified? Olly

45x3 minutes. That's less than we usually give a single panel image which won't be downsampled or stacked in superpixel. We just decided to see how it looked and it was OK. The very black, sooty parts would benefit from more data but I think we'll leave it as is, probably. Olly

Imaged with Paul Kummer. I didn't do a very good job of processing this first time around so I used a bit of full moon time to try again. RASA 8, ZWO 2600 OSC. I'm finding that Topaz DeNoise is very good, ironically, for sharpening. The tiny stars tended to look like noise but Topaz tightened them up nicely. Olly

Wowzer, that's dramatic! I love it and I also think it's an image that the advertising industry might love to exploit. Olly

I agree. You won't fix blue bloat with a bit of refocusing. You can attack it in cosmetic post processing but it's better not to have to. Olly

Albeit rather nervously, I think I'd say 'yes' to this question. There would just be another variable in the equations describing the consistency, no?

I wonder if there is something we are missing, though. Evolution by natural selection provided a mechanism by which the evolution of species is positively 'driven.' Perhaps there is some unidentified mechanism actively favouring the appearance of life itself. I've no idea what it might be, I only wonder if it might exist. Regarding UFOs, a phenomenological approach would be interesting. The researcher would try to list as many common factors as possible between all known sightings. My guess is that a fairly consistent profile of those doing the sighting would soon emerge, but I don't know if this has ever been done. I remain convinced that the way to look into UFO sightings is to look into those who report them, because a wide ranging random sample of people out and about does not produce a significant percentage of sightings. The 'cover up' hypothesis is not impossible but it is the first resort of every crank on the planet. Olly

Some people need there to be aliens. They have a deep psychological craving for them. Without them there is a void in their very existence. Some people, often the same ones, have a deep craving to be the ones chosen to meet or see them because they have a deep belief in their own superiority... born of an even deeper belief in their own inferiority. So, of course, they see aliens. Olly

I don't know how much blue bloat it will have but that can be minimized in post processing. I do see that it has a rack and pinion focuser and slipped focus from a Crayford cannot be fixed in post processing... I know that lots of words are devoted to glass type but I would rather see them devoted to collimation, field curvature and... the focuser. Olly

That's the best natural colour rendition I've ever seen... Olly

I think Paul spent some time trying different parameters in APP's mosaic making software. As regards post-processing, it wasn't all that difficult. Maybe four hours to get it nearly finished. After that I do tend to tinker endlessly over several days, but only in search of tiny improvements. Olly

I also wonder if the shock front is not compressing the interstelar gas and dust beyond the obvious shell of the loops. Olly

That is indeed deep, as Peter says. The Ha (lower right in this orientation) is also interesting because deep broadband in that part of the field seems to suggest a high concentration of dust as well. Olly

Nice point. However, might I not place a cube and a sphere on a gentle slope and observe that the cube never rolls down it and the sphere always does? You might reply by asking me how I can define a sphere and a cube without mathematics but could I not just hold them up and say, 'This is a cube and this is a sphere?' And then you might say, 'Always' means 'every time' and how can you discover that it's 'always' without counting the number of times the cube doesn't roll down the slope and compare this with the number of tries. By Gad, I think you are winning this one! lly

The judicious imager needs to look at the results of BlurXT intervention very carefully, for sure. Olly

I wonder if this is answered by Andrew S when he says It seems to me, a non-mathematician, that something may be unpredictable without being inconsistent. The outcome of a chain of events highly sensitive to initial conditions cannot be predicted but, when it has happened, it can be 'reverse engineered' and found not to have violated any existing models. Turbulence may even go beyond this and, if it does, might we not consider it to be a phenomenon existing as an isolated pocket of incomprehensibility within a wider matrix of comprehensibility? I wondered about the possibility of this distinction while writing my post. I'm still wondering about it! Olly

You can drill plastic with metal. You can't drill metal with plastic... Olly

I'm no longer up all night myself (Doctor's orders) so all my imaging is now done by automated remote control. My only point, here, was that I've not found mini scope-top PCs and hubs to be as reliable as good old desktops with plenty of USB ports. This solution won't always be appropriate, though, as I understand. Olly

I was only joking! As for 3D printing, I hate, loathe and despise it!!! Olly

Tricky. The term 'comprehensible' strikes me as being meaningless without the presence of an entity to do the comprehending. There can be no comprehension in a non-sentient universe. This brings us to the role of the comprehending entity: what capacity for comprehension does it possess? Any comprehension the entity achieves of the universe will be a product of both the entity's power of comprehension and of properties of the universe being observed. This suggests that what is comprehended is not the universe itself but a relationship between the observer and the universe. If I were to stick to this line of thought I'd have to say that the universe is not comprehensible, only our perception of it is comprehensible. Olly

I think you should certainly make two of these things, dear boy! lly

This opinion has been advanced in one way or another since Blur XT appeared. I think it may have its origins in the fact that Russ Croman trained his software on Hubble data, leading some people to conclude that it refers to Hubble images when processing the user's image. It doesn't. Bear in mind that Hubble has imaged a vanishingly small part of the sky over its entire lifetime so transcribing Hubble images into amateur ones wouldn't work at all. The Hubble images to do this don't exist. Croman used Hubble data because it is so good that any training performed on it will be as accurate as possible. Blur XT refers only to the image on which it is being applied. It performs an analysis of that image and then makes adjustments based on that analysis. These adjustments can be called guesses but they are very, very highly educated guesses. I find Blur XT simply gives tighter stars and a touch of sharpening. The image remains wholeheartedly the image. Olly

Galileo famously said that nature was written in the language of mathematics and it's hard to disagree. I used to beat myself up over why this should be but, more recently, I've come to wonder if there's really anything very surprising about it. My question to those on here who are mathematically competent (as I am not) is, Can maths not describe anything which is consistent? If it can, is there really anything more to the ability of maths to describe nature than that nature is consistent? And then, if nature were not consistent, would anything be possible - including thinking about it? Without consistency, would nature not just be noise? Olly