vineyard

Ok with a bit more time after dinner, and a glass of wine, here's another attempt.  Have done one more Curves Transformation (with a Luminance mask in place first) to darken the background, and then HDRMT, and then a bit more curves to change the colour balance a bit.  And also played with the v cool imagesolve tool - which showed me that there was an even fainter fuzzy caught!

Hello,

Hope every one safe & well. Here is M13 from last night. My first ever attempt at it.  There's a dust bunny at the top right hand corner (I need better flats).  I guess that fuzzy in the bottom right corner is NGC6207?  I did initially try using Dynamic PSF & MMT as well but I wasn't happy with my settings as it came out over sharpened.  I guess the optimal settings vary from galaxies vs clusters?

Cheers,

Vin

The colours & the textures are great, the stars are lovely.  Not sure that could even be painted better by a human starting from scratch!

Hello, just as an update.  I tried playing with PI settings as well (learning a lot about that in the process) & still no joy.  It is the oversampling that is causing problems for sure.  I must have just gotten lucky with night that the images did work & stack b/c when I look at astronomy.tools it says that with good seeing conditions, the TV102 & ASI178MC play nicely together, but with OK seeing, it leads to oversampling.

As final confirmation, I went back to M101 with a little PL72 last night & the ASI178MC and got lots of data that stacks  (and it makes such a huge difference when you have more data!)

So this has actually been a really useful learning session for me on the perils (and consequences...) of oversampling.

Cheers again for the help all & stay safe,

Vin

Hello,

I'm by no means an expert on this so will defer to others (in fact I tried starting with Astroberry but couldn't get it to work in a stable way so went the Stellarmate way (on the same pi) and that seems much better, fingers crossed).

I think the guide function on EKOS is a bit volatile (I also have occasional exposure fail issues).  Maybe try a couple of things: (1) the bin on the guide at 2z2 not 1x1 (which is what the screenshot seems to show it as) - the EKOS manual suggests 2x2, and (2) the exposure time on the guide (I have to tweak that from 1 to 1.5 to 2 sec depending on target).  This is based on ZWO cameras not QHY so I don't know about hardware side (& I use EKOS' internal guider not PHD2 so I don't know if that might also be making a difference).

Good luck,

Vin

Ah thank you.  I started with M81 and that one stacked fine, and then I just moved to M101 as the next target but didn't re-check focus.  Aargh.  Well, lesson learnt!  (And maybe an automatic focuser to do that every so often).

Thank you again vlaiv - v helpful & much appreciated.

(PS - one thing though, both of those lights were rejected in the stacking - the first image was the first night when I know my focusing was relatively good based on HFR.  Anyway, lesson learnt )

Sure thing - here is one from night one & one from night three.  Cheers, Vin

M 101 TV_Light_001.fits M 101_Light_112.fits

No joy sadly.  Still only used the same 48 lights out of the total 173 (!).  At least there's an explanation namely over-sampling.  I guess will have to come back to M101 once I eventually get the ASI294MC!

wimvb I'll have an explore on the PI tips, thank you - I see from a google-search advice on not using BPP but using SA & II.  So I'll keep fingers crossed & try that.  (I had tried PI as well - via BPP - but it came up with RANSAC errors and only found 3 (!) stackable images - which would be consistent with what you said about PI not liking big stars).

Now I'm starting to see the problems oversampling leads to!

Many thanks & cheers all.

Thanks all. Its really great the way people are so helpful in this hobby (or should I call it an obsession?  ).  I will keep my fingers crossed and try your suggestion vlaiv.  You'll be a sanity-saver if it works!

Stay safe all,

Vin

Hi happy-kat,

Thanks.  Here are 3 randomly chosen screen grabs (JPGs) - the first is one of the ones accepted, the other two are rejects.  (The only thing I've done is put their levels to the same new setting in GIMP just so that the image can be seen - happy to send screen grabs of an auto-stretch from PI as well if that'd be more helpful).

I've set star threshold to 2% and it only finds about 7 stars.  I'm beginning to wonder whether its M101-specific (for me anyway) - whether its v sensitive to focus?  While the focus on the third night wasn't as good as the second, with the same setup on the same night DSS still stacked M81 additional images fine - so maybe there's something specific about the dimness/relative emptiness of M101 (that's probably a really stupid idea but I can't figure it out!).

Anyway, scratching my head - may try a bit of M101 again tonight (w sharper focusing) or try a different target (its too disheartening to get nowt from a night, although luckily last night I did get more M81).

Stay well,

Vin

(PS - one other thing that comes to mind is whether its the camera & this target together. On another thread, @vlaiv & @wimvb pointed out that my ASI178MC is over-sampling with my fl 880mm/ f8.6 scope (comes out at 0.56"/pixel).  Could that be a factor for this particular target?)

Hello,

I was wondering if anyone might have some light to shed (pardon the pun!).  I've got about 100 lights of M101 that DSS won't stack.  I know a few of the last ones are out of focus so that's to be expected.  These were taken over 3 nights (about 170 in total!).  The second night's get stacked, the first & third night don't.  I've blinked through them all on PI and M101 is there (in fact the first night seems to have the best focus).

Has anyone experienced this before?  Should I just scrap the lights which it's not accepting.

(I don't think it was a kit problem on the third night - for example, I took some more of M81 last night too, and those get added & stacked to the earlier batches fine.  So it seems to be M101 in particular.  Do I need to up the gain on the lights?)

Thank you for any help,

Vin

Hello,

This is probably a v stupid Q. Is it worth using a UHC-S L-booster filter on M101?  I already use a LP filter, and do get data (just needs lots more of it ).  Given how dim M101 generally is, would an L-booster heighten the contrast against the deep sky, or just make everything darker?

Thank you!

Vin

So I was really unhappy with my butchery above.  Spent a lot of time looking at Light Vortex Astronomy pages (v helpful!) for my M57 attempt posted separately.  And thought I'd try again on M101 (practice in technique if nothing else).  Still nowhere nearly enough data, but there are a few more clear nights hopefully coming up

Stay safe.

Hello,

Here's the Ring Nebula.  I'm a bit more pleased with the processing here than the last M101 I hacked at so will revisit that with some of the stuff I learnt on this.  I originally took 90 lights but the last 10 got swamped by sunrise (it actually makes for fun watching it as a video on the PI Blink function!).

Cheers,

Vin

(PS - that's a horrid blue halo on the top right hand corner?)

Here's the same image but without being taken through GIMP (with just some sharper work in PI).  I think the non-GIMP version is better?

Hello,

So after my first galaxy experiment on M101 with a PL72 a few weeks ago, I went back with my TV102iis this week.  Took 105 lights x 120s over 2 nights.  Unfortunately something must have gone wrong the first night b/c DSS refuses to use any of those.  So the image below is best 80% of 50 lights from the second night (so only 1h20 worth of data in this image).  Following advice from @vlaiv and @wimvb on my M81 processing attempts, this is undrizzled & resampled to reduce size.

Not great (but an improvement on the PL72 image ).  Still scratching my head on why the first night's lights are being rejected buy hey ho, "computer says no" as they say.

The galaxy itself is not anywhere near as crisp as I'd like it.  And this image has had to be heavily cropped to remove the amp glow.  I did take darks but the ones I took at the same temperature only got taken as 8-bits for some reason so I've had to use older 16-bit darks that were at a slightly higher temperature.  Seeing the glow & the variability, I think a cooled OSC is definitely top of my wish-list now.

I also took about 3 hrs on M57 so that's the next processing butchery coming up 😄

Stay safe all,

Vin

20 minutes ago, smr said:

Can't think of anyother USB powered things I'd need to connect.

Do you think you'd ever end up using a filter wheel or an automated focuser?  Although I guess you could always add a multi-hub Anker into one of the USB slots at the time & still be fine?  Cheers.

That's amazing.  To think that all of us when we're hanging out with friends in beach bars etc on holiday, are on a little rock going around a little star that's going around with millions of others in one of millions of galaxies!  That photo is great for putting things in perspective. 👏🏾

Ah, I think I see. Thanks. I tried the undrizzled data, and tried to replicate the PI & GIMP workflow as much as possible (from memory rather than having written it down first time!).  I think this image does seem sharper than the previous drizzled one (but I'm never sure about my eyes at the end of a long day) - the centre seems more blown out but I'm hoping much of that is my clumsiness.  I tried to scale it to 2/3 size (using GIMP's image scale function) but I'm also never sure what that looks like on a screen until uploaded so fingers crossed.

Lots of learning today, so cheers again!

Vin

Thanks vlaiv that is hugely helpful.  And yes you're spot on - I checked my DSS settings and it was 2x drizzle!  That will remain unchecked now  and I'll try again on the linear workflow.

This is probably another stupid Q: when you say you resized to x6 smaller, do you mean the dimensions of the picture (just by changing the rectangle size by dragging)?  Or is there a sizing function that's hiding in plain daylight in front of me?

And thanks both vlaiv & wimvb for the feedback on the 294MC - I think that will be this year's treat.

Stay safe,

Vin

HI vlaiv, yes re the camera (the only other one I have is an ASI120MM mini for mono lunar & guiding).  I didn't take mosaics (not yet brave enough for that w EKOS) - I just set M81 as the target and took lots of lights over probably about 3 nights.  And then stacked them in DSS, and worked on the TIF file in PI.  Hmm, I did then open the post-PI TIF file in GIMP & GIMP did ask about a colour conversion - could that have been where the pixels changed?  Or maybe when I exported it as a TIF & a JPG from GIMP?  (On my DSS it shows as 3096x2080, but obviously something then happened afterwards in the chain but I'm not sure where)

No I don't have any reducers.  Ah re the ideal sampling resolution - I didn't appreciate that, as that is a whole area I have not yet got my head around.  I have played with the CCD Suitability calculator on astronomy.tools & I can see that it gives different recommendations.  But, must admit I don't know what that means in terms of image quality though (ideally I guess I could compare with a similar rig, two different resolutions & cameras and see the difference but don't have that hardware).

As it happens, b/c I am enjoying AP way more than I thought I would, I am planning to save towards a cooled camera now.  My current working hypothesis is that the ASI294MC might be the best one to step up to from where I am currently?  The CCD calculator says that would give about 1.1"/pixel which is still below the 2" that you recommend though?  I haven't yet decided that (even whether OSC vs mono) b/c that's a whole other area of research (well, it is lockdown ).  Are filters pointless with OSC?

Anyway, thanks for the tip on the resolution - could that also explain why my images always feel slightly less crisp & clean to me?

Stay safe,

Vin

Most of those lights were zero gain. On some (I think about 20-40 mins worth of lights, I can't remember precisely) it was gain 102.  The darks are also not at the right temperature in the above image (I took them but stupidly forgot to check their bit-size so they got taken as 8-bit which DSS won't let me use with 16-bit files - hey ho, another lesson learnt!)

That's an insanely rich field - they're like celestial fireflies!

Hello,

So I went back to M81 again during the week, and took more data (almost doubled it to 101 lights of 120s each, so about 3h20 of data).  And I used a different processing workflow in PI.  So while I can't really disentangle the comparative effects of the extra data vs the new workflow, I definitely prefer this newest image out of the three above.  So I suppose that's progress

Will try this new workflow on a couple of other targets that I grabbed some data for this week too, and see what transpires.

Stay safe all,

Vin

I don't have an autofocuser so can't compare on that I'm afraid.

But definitely some weird glitches w the guider module recently.  For me the thing has been that sometimes while guiding, the exposure fails (I use an ASI120MM mini) and so then it drifts a bit more (into the yellow zone) & sometimes cuts out the main imaging.  In the tinkering I've been doing, I found that setting the guide bin to 2x2 helps (I got that from their online docs), but also bizarrely changing the exposure time on the guide cam.  Two nights ago, if I was setting 1sec exposures it kept cutting out, I changed it to 2sec and it was fine.

I haven't had a chance to look at last night's lights in detail yet (will Blink them on PI) so can't comment for sure on last night, but whenever I checked on it, it seemed fine (except for one weird point when the guiding cut out, I noticed the binning had somehow re-set to 1x1 so I had to change that back, and then it restarted & stayed fine).

The guide module definitely seems slightly volatile right now.

I'll probably pass on setting up tonight, so good luck if you all are out there again - hope no glitches w anything!

Cheers