ollypenrice

Where do you see this? Mostly in stars or in nebulosity? RASA stars are not good, straight from the linear stack, but they can be fixed. (I'm becoming an expert at this! ) If I can fix it I don't mind. Olly

As would I. I'm bored by the slow systems I know so well. They were a great adventure for many years and a double FSQ106/Full frame CCD seemed like a wild adventure - and was - till I started working with Paul and the RASA 8-CMOS rig. Vlad may tell me that I'm dealing only in impressions, here, and he may be right - but what I feel is that I'm working with data which are different in kind from any I've worked with before. I can make different pictures from these data. I'm excited! I wasn't exactly a cheapskate on exposure time, either, with the slower systems. 20 hours was routine for a single panel. But when I drop those 0.9"PP 20 hour panels onto 3 hour RASA images to improve resolution, there is nothing there in faint stuff. We are in this for enjoyment (which can be hard to believe!) and, when it comes to enjoyment, give me the RASA. It's the difference between sitting on a nail and sitting on a sofa. I was a very reluctant convert but there is no going back. Olly

One caveat, though: the deeper the data the more effectively it can be sharpened. Olly

Rather than test the RASA on objects I'm not going to image, I'd rather test it on the objects I am going to image. That's my whole point: used as intended it performs extremely well on nebulosity. In the two images you post above, I would describe the resolution as very similar, the processing being different. Mine came from a widefield mosaic for which I needed dynamic range at the bottom end, in other parts of the image, leaving me with less to play with around the Bubble. I'm not concerned with comparing aperture with aperture. Its perfectly true that the RASA doesn't resolve as an 8 inch aperture would be able to do. What matters is how it resolves as an instrument with a 400mm focal length. As such, which is how it is intended to be used, I think the resolution is excellent. Olly

That's narrowband! And there is more information in ours everywhere except in the little strand from centre to 4 o'clock. Nope, you're not winning this one so far! lly

No, if you use luminance from a slower system you will simply darken out the wonderful faint nebulosity which the fast system is so good at finding. What is worth doing is using high resolution data (probably as luminance) to enhance regions of interest which the RASA cannot resolve to the same level. I find that the best way to do this is to register the high res, with stars, to fit the widefield and then de-star it. It can then be applied as luminance in Ps which allows you to manipulate its curve while it's in situ over the widefield. A seamless blend is possible. When you re-apply the stars, use only the widefield stars so they will be consistent across the image. Olly

This doesn't square with what I actually find in our RASA data. You and I have debated many times, over the years, you taking the theoretical position and I the empirical one. No reason to stop doing so now!! This is a close crop of the Bubble nebula extracted from a RASA 8 widefield. The image comes from a focal length of just 400mm. Pixel size is 3.76 microns in a Bayer Matrix. (I don't know how you feel the Bayer needs to be factored in, if at all.) I think that this Bubble is exceptionally well resolved for a focal length of 400mm. Dammit, it is bloody good for 400mm! Olly

Another RASA 8 image with Paul Kummer, who did capture and pre-processing. As well as the dark nebula there's the rather delightful little V1331Cygni with its circumstellar disk. Full size: https://photos.smugmug.com/Other/DUSTY-DARK-AND-MILKY-WAY-TARGETS/i-TbTwHRJ/0/c43a43f0/X5/LDN981 V1331Cyg WEB-X5.jpg Olly

Oh, I'm not so sure. I adhere to the phrase, 'Enough is enough...' It would only be a small paraphrase of Einstein to say, 'Time is what our body measures...' 😁 Olly

Not too near. I'm in the 05, Hautes Alples, at 900m altitude but, yes, it's hot. 35C today. Dark sky, though, which is why I find your image particularly impressive. Olly

Let's think about the word 'before' in the phrase 'Before the Big Bang.' 'Before' requires there to be a point on the timeline, a point which separates before from after on that timeline. (The present is also such a point, but it is constantly moving, whereas the point which separates before from after can be arbitrarily defined and fixed.) If we consider time to be a dimension which came into being at the big bang, there is no 'before' which can be placed on it because that dimension wasn't there. Accepting this isn't easy, but who wants easy? The idea that time wasn't there doesn't necessarily mean that nothing was there. Existence may have been going on in different dimensions, meaning that there was nothing 'before' the BB but there may have been something 'outside' it. Also, the idea that there is a past, a moving present and a future is what kind of idea? It is, dear friends, a theory and it is a theory which has taken some heavy knocks from theoretical physicists... I'm convinced we need a more generalized theory of time. Olly

It's usual to see this in Ha/OIII/LRGB, OIII being essential for the Squid, of course, without which it just isn't there! However, this is pure broadband using OSC at F2. What's different, here, is the amount of dust overlappng the emission nebulosity. I'm coming to think of results like this as MDLG images, or More Dust Less Gas. Well, it makes a change. Paul Kummer drove the scope and pre-processed while I post-processed. Robotic RASA 8/EQ6/ASI2600MC based at my place. Bigger one here: Bigger one here https://photos.smugmug.com/Other/Emission-Nebulae/i-3MGGvVn/0/ae7e2d60/X4/SH2_129_OSC FIN 2 WEB-X4.jpg We also got a result on the Propellor Nebula but it turned out not to be very interesting so here it is as a stocking filler:

Beautifully done and from near Paris??? Congratulations! (I live not too far from where Stéphan discovered the Quintet.) Olly

The design may have changed slightly. On mine the rear element was vulnerable, at least from memory. Anyway, better safe than sorry! Olly

The 150 wins - on this target - but would it beat a larger RASA? I often drop old TEC 140 data onto RASA 8 widefields in order to tweak up the resolution in regions of interest, but what I find pretty shocking is how shallow the high res data are. Even in 20 hour TEC runs I have a black background sky while, in the RASA with 3 hours, I have structured faint dust. Olly

I did look through my FSQ85 and it was truly remarkable for its aperture. On the other hand, it's heavy and it would be easy to have more aperture for less weight. Don't scratch the rear element with your diagonal - not that you haven't thought about this. Olly

Great stuff. I'm a fan of this target, for sure. Olly

The hallmark quality across the board. This is also great in widefield. Olly

^^ Dead right about the roof. If it can collide, one day it will collide. I host six robotic instruments. We've had 10 micron, Avalon Linear, Avalon M Uno, EQ6 and Mesu 200 mounts in residence The Mesu is the very clear winner on reliability. Including mine, there are four of them here now and, touch wood, they never go wrong. As Andrew says, you need someone competent on site. Remote from an untended site is, in m view, a non-starter and very risky. I'm called up to the sheds several times a week because things just do go wrong, often inexplicably. Mostly it's switching things off and on again, unplugging USBs, putting mounts back on their park positions, etc. Personally I would avoid all scope-top mini computers. I've replaced quite a few and of various makes. I think the best solution is a desk-top machine with lots of USB ports, so no hubs of any kind. I don't know how fast internet connections are in the rest of the world but it might be worth planning to do your stacking and calibrating on the observatory computer so you only export a final file. We have no choice at my place. Another very unreliable item is the UPS. They tend to have shortish lives and they don't like getting hot. Reliably clear skies and high daytime temperatures often go together. You do need them but be prepared to replace them regularly. Once a year might be the average. There are good providers in Spain nowadays. They're not cheap but you'd be surprised by how much work is involved in running a robotic setup. Olly

This is certainly the key distinction. We can call the photons 'object photons' or, alternatively, 'wanted photons.' If you don't want them, there is no time gain in capturing them. My thinking is that there is no point in talking about speed until you have decided what picture you want to take, and my beef with Starizona is that they ignore this. And I think they do so intentionally as a piece of marketing hype. I might just as well say, 'I can make your car ten times faster by reducing your journey length by a factor of 10. ' Olly

I think you may be over-simplifying the mosaic versus single panel alternative. Suppose you want field of view 'x.' You can shoot it in low res, fast F ratio, short FL widefield in one go or shoot it in 4 panels in higher res, slower F ratio, longer FL. (Obviously you could also shoot it in super fast F ratio, larger aperture, longer FL, but not for the same approximate price!) If you go for the mosaic, and resample downwards, you do not need 4x the exposure because you can downsample each panel to a quarter of its area, so boosting the S/N ratio of each panel. The choice really is a complex balancing act and is a very target- and intention- driven one. An irony which constantly amuses me is that I never mosaic with my longest FL setups and almost always mosaic with my widefield ones. Besides, until you have spent a week of 8 hour days grappling with a 35 panel mosaic, you haven't lived!!! Olly

It is, as you suggest, used to make a totally meaningless comparison. Where is the 55.8 mm telescope in this discussion? It needs to be there at F2 in comparing the Hyperstar with something meaningful, or there at F10 comparing the native SCT with something meaningful. Why? Because the 55.8mm scope has a light collecting area 25x less than the C11. This topic always produces more heat than light, to quote MartinB, and I'm guilty of perpetuating this! lly

About 55 x 3 mins per panel, Steve. Almost shamefully short! Olly

However... I'm currently working on a vast mosaic including the Veil, and the line of brown dust rising from the tip of the WItch's Broom seems to carry on for a long way, so the alignment between the broom and the dust may be chance. To be continued... Olly

Yes, but my question is, '25x faster than what?' Edit: With a bit more free time I can now answer that question: it's 25x faster than a telescope with an aperture of 55.8mm and the same FL. Olly