AKB

@catburglar was gracious enough to send me the raw stacks of the above images, in order to investigate the potential of Jocular's latest noise suppression. Here are the results which I managed to get, and which are arguably a small improvement on those he showed. I'll post some further guidance / suggestions for parameter settings on the Jocular thread itself. Tony

Would be most interested in seeing the FITs files of these captures (stacked). The noise looks of a slightly different nature from what I’m used to seeing (maybe pixel resolution?) and I’d be interested in using these as benchmarks for further noise suppression development. Thanks if possible to PM them. Tony

Arp 18 So much going on here. Arp 18 turns out to be NGC 4088, VV 357, and in the wider field we also have VV 1504 and NGC 4085, plus a host of more distant galaxies. The close-up of NGC 4088 shows why it is described as "spiral with detached segments". The catalogue shows it to be 40 Mly distant but 'nearby' galaxy PGC 38369 is much further away at 845 Mly. Even more distant are PGC 3411579 (mag 18, 1045 Mly) and PGC 3411583 (mag 18.7, 2663 Mly). NGC 4085 and vicinity 62 Mly away, classified as SABc(bar) is magnitude 12, and easily outshone by the magnitude 8/9/10 stars in the same field. PGC 3411573 is aroung 3.5 Gly away. VV 1504 This galaxy cluster is about 900 Mly distant, but PGC 3411607 is around 3.3 Gly and magnitude 19. All in all, another splendid area of sky (but there again, what isn't?) Tony

Bit of an Arp-fest last night, taking in some of the vistas in Ursa Major and Canes Venatici: Arp 18 Arp 27 Arp 269 Arp 281 Arp 299 I can only find 269 previously posted on this thread (twice by @Mike JW) here: https://stargazerslounge.com/topic/351721-arp-galaxies/#comment-3882086 https://stargazerslounge.com/topic/351721-arp-galaxies/page/4/#comment-4042150 so I'll just add my images here, and not repeat the discussion. The widefield gives some nice context, but the narrow is pretty similar to previous postings. For the others, I'll add separate posts once I've absorbed some of the information and background on them. Tony

I believe you're to blame for the sharpening addition! So thanks for that suggestion. Tony

Perhap slightly less cryptically, thanks to Martin's software expertise, and possibly egged-on by several users, the latest development version of Jocular sports two what-might-be-called "post-processing" features: sharpening, and noise reduction. These two contrasting [sorry for the pun] and somewhat complementary features are operated from sliders on the ring, and static settings under the configuration's Monochrome page (not sure about the name, perhaps Martin will explain.) Slider sharp, configuration parameter radius, this is an implementation of an unsharp mask. Slider TNR, parameters noise reduction kernel and kernel size in pixels. The noise parameters probably need a separate post to fully describe their effect, although I'm sure that Martin is working on the documentation as we speak 😉. For larger images, the current implementation of the noise reduction can make the response times a bit sluggish. Best practice, at this time, is probably to set both sliders to their minimum values, effectively switching them off, until final cosmetic tweaking of the image is required. (Perhaps this should happen on every image reload??) I've already posted one example of this processing here: https://stargazerslounge.com/topic/349834-cancer-arp-82-shk-185-hickson-37/#comment-4226745 But I attach another below: no processing sharpening only sharpening + noise reduction Tony

Looking again at the wider field, I've only just spotted these in the top right-hand corner!

Yes, that was you (but many thanks for the latest updates!) This camera is really quite low noise (especially running at -10ºC) so on its own, the noise suppression probably doesn't have much to offer in this case. I adjusted the levels so that you can see the background noise. Once sharpened, however, the high frequency noise can be pushed back somewhat. Here is a sequence of three images: no sharpening or noise suppression with some sharpening (and no other changes of level) with sharpening and noise suppression (again, no level changes) We do, now, have more than enough parameters to play with, so this is hardly a definitive example. Perhaps we need further discussion on the Jocular thread, or somewhere more appropriate. Tony 0

Quite at random last night (a bit fraught what with testing software and a recent camera change) I settled upon Arp 82, aka NGC 2535 + NGC 2536, or VV9 (always a problem to know where to post these things!) Wide field shows it in a wonderful star-studded background (some actually rather bright stars) and a plethora of galaxies, some that I can detect around mag 18 at formidable distances (2–3 Gly) and others, according to the chart, at around mag 20 at 6 Gly, that need the 'eye of faith'. The zoomed-in images don't really add anything to the observations above, but I was, anyway, delighted to have stumbled on these gems... I really must learn to plan better, although, once again, this was really a bit of a shake-down for the gear. Tony

Here's my Abell 610 effort from this evening. Transparency didn't seem to be very good, though. Various states of zoom, from wide to narrow. Busy with other task this evening, so not much more to say about this one (yet.)

Spoilt by a few clear nights, and the prospect of a few more, I spent last night collimating and testing my new (well, used, bought here) ASI294-MM attached to my 9.25" Hyperstar. I normally use this for EEVA, but the targets I used last night were not really my usual tiny galaxies, but much more familiar larger ones plus some globulars. All done to test detail and reolution. All the shots are stacks of 10 minutes or less, each with 30 second frames. This left lots of time for tinkering, but also ended up with a fair number of images more suitable, perhaps, for this forum than the EEVA one, since I'll attach no detailed commentary for what are, after,all, verywell-known objects for the most part. You can see why I re-took M106 again, later in the evening! I just think it's amazing what can be done with a short imaging time and a cooled CMOS camera these days... Hope this eclectic mix is not inappropriate for this Deep Sky imaging section. Tony.

Bit of a disaster...

Thanks for hugely fast response! I've PM'd a log. For platesolving, I think it just seems to be 'too many pixels' ! Although it's only about 3 million vs. the 1.3 of the Ultrastar. Cutting it down to 1600 x 1200 seemed to work, although maybe it's an issue of centering the target in the FOV too? The Ultrastar will live on, I'm sure, it's such a great camera, and so easy to use (no power lead is important when using a Schmidt configuration.) But I was just curious to see how cooled CMOS compares to uncooled CCD, and even from just last night with Saharan dust and poor transparency, I have to say that the noise levels seem to be spectacularly low when cooled to -10ºC. Happy to continue this issue by PM.

@Martin Meredith Having very recently swapped EEVA cameras, I've run into a couple of problems with Jocular: wrong-sized flats (from old camera) being applied to new images plate solving fails for new images This all seems to come down to image size / number of pixels, so for reference the cameras in question are: OLD: Ultrastar uncooled mono CCD, 6.4µm pixels, 1392 x 1040, 11.2mm diagonal NEW: ASI 294MM cooled mono CMOS, 2.3µm pixels, 8288 x 5644,23.2mm diagonal Now, obviously, there's a huge difference here, and for 'normal' EEVA use, I'm binning the new camera x2 and using an ROI of 2048 x 1536, for a diagonal of 11.8mm. But it is still twice as many pixels (which was the whole point, to improve sampling.) Flats: Seeing as the image pixel sizes are difference, I was very surprised to fins that somehow the flats from my old camera (which was recognisable as being fairly dusty) were being applied to the new image. How is this happening? I haven't yet tried to make flats for the new camera, but it's actually very clean. It would only be to reduce vignetting. Plate Solving: I'm presuming that there's some sort of limit that I've reached here. I experimented by cropping a new image slightly and dropping that into Jocular, and it solves just fine. This is after having adjusted the pixel size and binning factor in the configuration menu. I'm most concerned about the flats, although this may be solved by simply taking some new ones, but it's also an issue for plate solving and identifying small targets. If necessary, I could perhaps work around this by reducing the ROI even further. I should just add that the ROI is done in the capture software (ASIImage) outside of Jocular. Thanks for any suggestions. Tony

Now you’re talking! Can’t wait to see the RGB. …I wish I could do the same. Not brave enough to try it yet. Previous mount didn’t need to do this! Tony

Yes, perhaps, Wim’s whisper of a woolly waft.

By proxy!

Well, we will see you posting in the EEVA Observations section, then?

Reading further, I see that NGC 2854 and 2856, captured above, are parts of Arp 285. The spiral arms of NGC 2854 are clearly visible, but look more closely at NGC 2856 and you can see evidence of the jet leaving at a right angle to the main body of the galaxy (a barred spiral, although I couldn't tell).

I was so keen to take a look that, seeing a short clear window forecast last night, albeit with high winds and some high cloud, I flung open the observatory roof and with no opportunity to let the scope cool properly, or to focus (which is a bit of a killer for a Hyperstar), I captured 10 minutes-worth. This is a spectacular region of space. The widefield view (nearly one degree across the diagonal) gives agreat panoramic vista, with Arp 1 as the centrepiece. The bright star is 39 Lyn / HD 80608 and the two galaxies to the lower left of it are NGC 2854 and 2856. But this field has so many galaxies, especially towards the top of the frame, there are too many to label and the Jocular display becomes peppered with markers if you try. The haze around the stars and the general fuzziness is probably a combination of high cloud, poor focus, and inadequate cooling time. As a result, perhaps, I'm unable to resolve the bridge between the arms, but I've tried to emulate the FOVs from @catburglar to see the comparison. What a great galaxy, though! Tony

Thanks for that. If I was starting again I might just go for a RASA. On the camera front I am thinking of trying an ASI294MM, a cooled CMOS mono camera with slightly smaller pixels than the Ultrastar, which I believe to be under sampling currently at 2.5”. The ASI would give me 1.8”, but really low read noise and high sensitivity. Tony PS: I’ll be adding Arp 1 to the observation list!

Inspired by this recent post in the imaging section... ... I set out to look for it myself. Here's 20 x 30 sec from my 9.25" Hyperstar / Ultrastar EEVA rig: It's barred spiral galaxy about 60-70 million light-years from Earth (some variation when I was trying to look this up), in the constellation of Ursa Major. According to Wiki, the central bar is approximately 500 million years old. Initially, I was interested, as usual, to see what deeper fuzzies might be around, and I've labelled some of them in the image: 2653194 – Mag 17.7, 1382 Mly 2649365 – Mag 18.8, 3138 Mly 2653742 – Mag 19.1, 3636 Mly 5339316 – Mag 19.7, 3880 Mly (the faint one to the right of the brighter star) 3382663 – Mag 19.1, 3809 Mly ... no idea how accurate these distances really might be, given the variation I found on NGC 3359 itself. However, reading further, there's something much, MUCH more interesting going on here: NGC 3559 is "devouring" a much smaller galaxy, nicknamed the 'Little Cub'. So nothing terribly unusual about that, but this is a very special galaxy. There's a really interesting report here: https://news.ucsc.edu/2017/07/little-cub-galaxy.html describing it thus: "As the Little Cub has remained almost pristine since its formation, scientists also hope its elements will reveal more about the chemical signature of the universe just minutes after the Big Bang." "The Little Cub was initially identified as a potentially pristine dwarf galaxy in data from the Sloan Digital Sky Survey (SDSS). Follow-up observations were conducted using the 3-meter Shane Telescope at Lick Observatory and the 10-meter Keck II telescope at the W.M. Keck Observatory." There's an image in that report, presumably from one of those scopes – was there any chance that I could detect it ...???! It's just outside the above FOV, but here's a negative zoomed in on the relevant area: There's a very, very faint smudge at around 4 o'clock at the edge of this image, just to the lower right of a line of three stars, which just might, with the 'eye of faith', be a hint of it. This was the only EEVA image I took yesterday, being otherwise occupied, but I had also set up my imaging scope (Esprit 120ED, F7, ASI294-MC) to capture about 2 and a half hours on the same target. Very stupidly, because I had been in a rush, I forgot to turn on the cooling, so the colour image was, frankly, worse than the EEVA one, but here's a crop of that too (vastly over-stretched): Smudge in the same place ??? So exciting. I'm going to go and look for this more carefully on my next EEVA session, since the mono rig is clearly much better at this than the colour imaging one. Tony

Of course, you can always go on and construct more complex examples which make an algorithm fail, but it’s a moot point, as you said yourself… It’s really question of what’s good enough for practical purposes, and I think that the OP has hit the nail on the head… Tony

Just try it. I think you’ll have a good outcome.

In this case, if you have estimated the stack variances (and many processing systems do just that) then there’s a simple formula which provides the minimum variance estimate of a weighted average of the stacks.