imakebeer

It was cloudy here earlier but your pic made me go and check again - as a consequence I've just spent the last hour throwing the scope outside in a bit to get some more data for my own M31 2-panel mosaic! 👍🔭 I think it's looking good, I don't think it's too much, and the overlap isn't leaping out at me. I can't remember if you're stacking with Siril but if you are, rather than simply throwing away all the initial session data you could use the registration plot to manually select the best frames from each session and combine them (if you aren't already doing this).

Looks good mate 👍 Out of interest, what are you using to stitch the panels together? You saw my recent M31 pic from the other day which looks very blotchy in comparison and with a much colder, bluer looking core... Whereas your image is overall much smoother with a warmer more yellow core... But - I used a NB filter and I think I can see some red-pink Ha stuff in there even in a poor image. Not sure if your already have a NB filter, whether you could grab some data and add it to your existing broad band stuff???

So in general when one makes an Ha + OIII image you're not using any RGB then? I was under the impression you're meant to blend it with a bit of RGB, e.g. in the red channel you mix a bit of R + Ha. But maybe the stuff I read on Astro Backyard has just confused me...

JFYI, this is what I managed to get so far for M31 - don't laugh! (it's ok really, you can laugh a little bit) This is my first ever attempt at a mosaic, and I realise a NB filter isn't ideal for a broadband target! Only 2 panels, 40 x 3min = 2hrs per panel I took some new light frames (x20) this morning but had to use an offset of 4096 in Siril as 1024 just doesn't seem to work with this target so far. Not dreadful but clearly needs work - through inexperience I just manually blended the two frames together in GIMP and did my best to try and match the colours. Didn't really stretch it much, just adjusted the black point and did a bit of layer masking to tidy up the noisy background. I feel like maybe the flat frames are all over the place so perhaps an LED tracing panel is needed to try and bring some consistency to proceedings.

Do you have a link? I assume one might find such a curio on Amazon? 🤔

When @TiffsAndAstro said tablet I understood large Android device or iPad type thing. But LED tracing panel sounds somewhat more cost effective 👍

I think a credit card might be needed if I am to acquire a tablet big enough to stretch across a SW150PDS 😜 Also, having just ditched the laptop and cables for an ASIAIR I'm reluctant to rush to use NINA or more softwares than absolutely necessary (notwithstanding the very reasonable argument that the ASIAIR alone is not exactly working out for me at the moment! 😖😂)

I think you're right, I think there is value in making flat production more rigourous and repeatable. My current method of a white T-shirt and a grey wall in a room with varying ambient light is not going to be ideal in this regard. Now where is my credit card..... I've been pondering this some more. I think you're right, I think both the ASIAIR and Siril are scaling the raw files to 16-bit. I'm going to re-process my decent-ish images of both the Crescent and Veil nebulas with an offset of 4096 and see what comes of it - when I processed them initially with an offset of 1024 maybe I just got lucky but for some reason this luck doesn't extend as far as M31???

Yes I think it may well be. I think Siril is doing same/similar too. I noticed after my previous post that the FIT files from both the ASIAIR, and when Siril converts CR2 to FIT, the FIT files have roughly 1.5x as many pixels in each direction compared with the original RAW CR2 files. Maybe it's always doing it, just that for some reason with the Crescent Nebula it wasn't such a big deal??m Yep, up to date - TBH it seems it won't let you proceed unless you agree to install the latest update every time one is released!

I agree, and my experiemnt above suggests this may well be the case. If you happen to have the opportunity at the weekend to repeat my experiment I'd be interested in the outcome just to be sure I'm not being a total bonehead, i.e. select the option on the ASIAIR to write files to both the SD card and the Air, then compare...

Umm... no, that's not quite right. In 1 night I imaged 3 targets, so 3 sets of light frames. But I only took 1 set of flats, i.e. use the same set of flats for all 3 targets. Nothing changed on the camera or imaging train, no change in focus, so as far as I'm aware 1 set of flats should be OK here - right? But what's odd is I could process The Veil Nebula fine with an offset of 1024. But when I tried the same with M31 I got dust spots - I'm reprocessing now with an offset of 4096 but I'm not totally convinced it's working right. I think the dust spots are gone but there still seems to be banding and noise (or something), even after removing banding in Siril and then de-noising in GraXpert. But in other news..... I've been experimenting taking bias frames at 1/4000s: Using just the DSLR (i.e. ASIAIR powered off) I got 5 x Canon RAW *.CR2 files - they all have a "Mean" of about 1024 Repeat with ASIAIR on but also switch on option to save files direct to DSLR SD card - very interesting, the FIT files from the ASIAIR all have a mean of about 4127 whereas the corresponding *.CR2 files from the SD card are all about 1024. Interesting.... Edit: Further observations: The Canon vs. ASIAIR bias frames are different "brightness" (different offset?), but when viewed in Siril using "Histogram" mode they are near as dammit identical with just two key distinctions (in addition to the brightness above): The ASIAIR FIT files seem to be mirrored about the horizontal axis. Flip it round and then they match with the original Canon RAW files The ASIAIR FIT files have a mysterious line of white pixels along the top of the image (or bottom if you flip it). I think it might just be a line 1 pixel high, but this is not present in the original Canon files. I'm curious now to see how Canon vs. ASIAIR flat frames compare.....

OK, more thoughts about the ASIAIR and offset after a bit of Googling..... From CN - "ZWO knows what offset works for it's cmos cameras (same with color balance), but for DSLR's maybe it just uses a fixed 'safe' value" From a ZWO tecchie on their forum - "Offset is not visible in ASIAIR in order to make things easy as our slogan says "as easy as 1,2,3" " And from right here on SGL - "IIRC others have commented that ASIAir does not provide a user-settable offset." I bet ZWO have hardcoded into the ASIAIR an offset of 4096 (approx. = 4100!!!) when they convert DSLR RAW files to *.fit (or something like that) haven't they! So maybe this wouldn't matter if I was using real bias frames but it will impact of using a constant "1024" offset in Siril.

Many thanks @alacant - some thoughts/comments on the above..... (sorry, bit long, but please bear with me...) OK, so in the statistics from Siril the "Mean" value is the offset, right? I'm not imaging in a hot climate - South East of UK which is mild to cold at this time of year. I recall that night was fairly mild. I'm powering the camera from a mains power supply with a dummy batttery, but I've always used that with this camera. I'm not recording to the in-camera SD-card, the images go straight to a USB plugged into my ASIAIR Mini (could be a clue here.....) I took a break from AP between May 2023-August 2024. The camera was stored on the scope in the garage during this time, which can get warm in the summer and cold in the winter. Possible damage here? I had the camera modified in March 2023. But I went back to the bias frames (1/4000s) captured in April & May 2023 (i.e. after modification) - loading these into Siril they show a "Mean" value of around 1024, exactly as expected. This was long before I had an ASIAIR - back then I was using BackyardEOS to control the camera (using the same power supply and data cable as now) Lately I haven't been taking bias frames, not since you told me about this 1024 offset instead - but I did take some before I knew about this, with my first session with the ASIAIR in Auguest 2024. And the Siril statistics of those also show a "Mean" of about 4100! So now I'm wondering either: Did the camera get damaged somehow while not in use for ~18 months? Is the ASIAIR doing something to the files? I note that the ASIAIR always gives me *.fit files whereas when I was using BackyardEOS I always got Canon's native RAW *.cr2 files. Could it be the ASIAIR messing something up when it converts the files??? Easy enough to check this! Hahaha - you're absolutely right! 🤣 But I can work with a solution for now, and think about explanations in the meantime. Thank you so much for your continued help, I really do appreciate it 👍

3 x "bias" frames @ 1/4000s exposure - https://drive.google.com/file/d/1-qH-pOViRufmsaWUsvPDqh4s-H5Xzyby/view?usp=sharing The optical train literally hasn't moved since I took my successful images of the Crescent Nebula - so yes there is a filter in there (Optolong L-eNhance) but I didn't add it specifically for this session. So no new lenses or filters, didn't even rotate the camera. The only thing that could have changed between sessions was the focus, and that was just a slight tweak between sessions to check it was still in focus. TIA 👍 Edit: Is the offset the sigma value shown here? If so, close, but not exactly equal to the 1024 I'm using (and doesn't seem to vary between frames) 🤔

Should this be B=Oiii or B=zero?

Thanks in advance dude: 3 x lights of M31 - https://drive.google.com/file/d/1-H0yU6_BEnHInaSsNt3stXHrz43FuXVe/view?usp=sharing 3 x flats @ 3s exposure - https://drive.google.com/file/d/1-Cf8jh_l0xRcDNGXy3HgNN9pL73Gc6vG/view?usp=sharing 3 x flats @ 5s exposure - https://drive.google.com/file/d/1-ER6TmXu5YO4R9_h4x9hVJFId4ABuK_2/view?usp=sharing

Hello, me again... 🤭 @alacant (or anyone else for that matter) can you offer any suggestions why my flats seem not to be working for M31..... The Crescent Nebula is sorted now - thank you again everyone for your help. But the other night I imaged: Veil Nebula NGC6992 Andromeda Galaxy M31 (2 panel mosaic) California Nebula NGC1499 The Veil Nebula worked out fine, Cali Nebula is still in progress, but on M31 it seems like my flats haven't worked again ☹️ The processed images have very obvious dust motes which plagued my previous images of the Crescent Nebula until we solved the issue. I've used the same set of flats for all targets since nothing changed between them I took 20 x 3s flats, then also 20 x 5s. In both cases the "level" (whatever that statistic Siril gives is) is about 4000-5000, i.e. well below the ~8000 we discussed for half well depth. Issue is present with both sets of flats, but seems worse with the 5s ones Any ideas? M31 with 5s flats Stats for a typical 5s flat

Nice image @PhilB61 👍 I've recently just started using a NB filter myself (Optolong L-eNhance in my case) - so far I've managed to produce a nice RGB image of the Crescent Nebula but like you I'm struggling to figure out how to add Ha & OIII to this. Can you elaborate at all how you did it, or point to some useful videos? I've extracted the B&W Ha & OIII images using Siril, and stretched them a bit, but in GIMP I'm damned if I can get it to recombine, say, Ha + R (or B or G + OIII), let alone recombine all 3 channels into a colour image. I think I know what I'm trying to do, just not the actual clicks to make it happen 😣 I'm too much of a newbie to give a definitive answer but here's my guess what's happening: Just like our own Sun stars emit a broadband spectrum, literally all the colours of the rainbow (and more!). A NB filter is filtering out almost all of this except for maybe 2 or 3 narrow bands of the spectrum - the benefit is that you can capture the subtleties of what is emitted from these nebulae, but comes at the expense of filtering out the rest of the spectrum and hence a lot of the colour of stars. I would guess it is a similar issue with galaxies - they are comprised of many stars so also emit a broadband spectrum, which I assume is why I've been advised that a NB isn't suitable for galaxies (and probably why the images of M31 I've captured with my NB filter are distinctly lacking in colour! 🤣) I had the same problem with my image of the Crescent Nebula - in my case I had already captured some unfiltered data which made for really rubbish nebula images but preserved the star colours. So the image shown is actually a "cheat", a composite of an unfiltered star layer + filtered background/nebula (and of course they weren't quite aligned so I had to mess around to realign them and then crop etc)

Apologies for the zombie thread revival but can anyone tell me how to remove or uninstall this shortcut/app/whatever from Chrome on Android? Every time I click on a Google search result from SGL it opens in a new window by default which is not too my liking - I prefer to have multiple tabs and groups open. Since I can't figure out what it did when I "installed" it, I can't figure out how to remove it 😖

Thanks, yeah this was something I had mentioned in the other thread, good spot 👍 It's much more obvious when the star layer is hidden. I do wonder if it would stand out more with more data but as the weeks and months roll by time on this target is becoming more limited, so maybe next year 🤞 (I'm just starting to dabble with mosaics which I think would also allow me to do more justice to the surrounding region as the FOV with my 150PDS is quite "zoomed in")

I'm assuming you've seen the film "Alien"? It's been widely pointed out over the web that the Veil Nebula bears an uncanny resemblance to the alien, including right here on SGL... I was imaging it again on Thursday night actually, this time with a filter. Hoping to find time to finish processing it over the weekend. Regarding the stars, not sure what software you're using but... I always separate the stars at the end of my Siril processing using the Starnet plugin - really helpful so you can stretch the stars and background independently of one another. By default you should end up with two separate images, one of the background, the other of the stars. I use GIMP for final tweaks (PS is very similar) - you can import the stars and background as separate layers and play around with blending the two. Personally I tend to put the star layer on top with blending mode set to "Lighten Only" and maybe reduce the opacity to 50% so they aren't so stark and to stop them dominating the background.

It's been a long journey and I've had a ton of help with this image in another thread from lots of the kind folks on SGL - many thanks to everyone who offered advice and encouragement, special thanks to @alacant who finally figured out why my flats weren't working! Anyway I think I'm finally happy enough with this image to share it here. It's been a fun exercise and I've learned something new about pretty much every aspect of AP along the way. SW150PDS + Canon 450D (modified) + Optolong L-eNhance filter 59 x 3min useable lights + 20 flats Processed in Siril, GraXpert & GIMP

I assume it will work a bit like Starnet and you'll have to define somewhere in Preferences where the executable is. Meanwhile in other news - slight tweak to the core, I think I'm happier with this:

I've looked before and was looking again earlier - I can't see where you can access this development version ☹️ (but yes it would be jolly handy to incorporate GraXpert into my Siril process, similar to Starnet.....)

Right, here we go - I've done a bit of stretching in GIMP. Honestly I've been staring at this thing for so long now I genuinely don't know what to think anymore 🤣 I cut the blue a bit as it was looking a bit magenta, but looking on my phone I think it might be a bit orange now.....