First proper guided image - Rosette Nebula

[AndyUK]

After a semi-disastrous attempt at the Horsehead a week ago during the full moon (my first real (imaging) light with the NEQ6, MN190, Synguider and modded 40D), tonight was the first clear(ish) night since - I managed to get 10 subs before the clouds moved in (and my battery pack went flat ).

I know my processing leaves a LOT to be desired, but here is my best 600s sub (put through CS5) just to see what it would look like (no darks, flats or flat darks).

I know there's still plenty of room for improvement (I'm not sure what's going on top right with the shape of the stars ?), but I just thought I'd share this processed frame as this is really the first time that I've managed to get everything together on a fairly reasonable night (and I'm hoping starts to justify the expense!)

If anyone has any critical comments, please do fire away (especially if they have any ideas about what's going on with those star shapes ?).

I'm now going to stack the rest and add/subtract the darks/flats etc and see what the final result comes out like...

[MikeWilson]

Hi Andy,

I'm sat up this time of night trying to figure out why a hot water tap is leaking and I thought I'd have a break and check SGL. And boy was I treated to something special - I saw your image and said out loud, "Wow, that is f*&$%*g spectacular!".

Now that I've said it, it's worth mentioning that there is obvious vignetting (flats will deal with this) and there appears to be some tracking/guiding errors but nothing to write home about. Was the SynGuider properly calibrated before you made the exposure? Do you remember the values displayed on the screen at all? (particularly the aggression..)

All in all though, this is a tremendous image. I bet you are really, really pleased right now!

[AndyUK]

Cheers Mike..! I must admit, I am quite pleased with that for a single frame...

Hopefully the flats will make an improvement (I actually took some tonight - Only the 2nd time I've done it ). I'm just stacking it all now (for the 2nd time - my laptop ran out of memory )

I *think* the synguider was tracking okay (I did calibrate it - I've learnt that lesson now!), but now that you've mentioned it, the agression was quite high and the exposure was fairly low (128ms), but I noticed that there was also a breeze about tonight so that wouldn't have helped either... I suspect that may well be the problem.

(I hope you figure out a fix for your hot water tap...!)

[MikeWilson]

Hi Andy,

I'm not sure everything was ok with your guiding. It was guiding yes, and you were tracking but I've often gotten those bean shaped stars and it's usually a combination of one of the following factors;

1. Poor alignment

2. Temporary poor seeing (a cloud quickly passing between the scope and the guide star)

3. Wind/cat kissing the mount legs

4. Aggression too high (causing the guider to over continually over-compensate)

When I last attempted to image (it was using the SynGuider on my early December M42 picture) I had some of my frames come out with stars like those. It's just a temporary thing and they're not all like that - plus some are worse than others.

Since then I've changed to a QHY5 and PHD but haven't tested that yet. I have to learn how to guide all over again it seems :\ However I'll let you know whether this approach helps eliminate the bean stars (or not).

(as for the hot water tap - a plumbing web forum has given me some sound advice that I shall implement forthwith and then commence laundry operations!).

Great image, Andy. I'm really pleased for you especially after all our long discussions about guiding/imaging over the past few months.

[AndyUK]

Cheers again Mike...

I did read that it was advisable to reduce the aggression by half (but I've only just re-remembered - I'll try that next time). There were also a few thin clouds scudding over as well... but as for cats - No... Not in our garden. The local felines haven't cr*pped in, sorry, been near our garden (front or back) for some months now (the dog might have something to do with that, and he wasn't out tonight either), but thanks ever so much for the pointers - I'll pay particular attention to those next time the skies are clear (whenever that will be ?)

I'll have a look at the other frames and see if they're all like it - I had hoped to get a full 5 ish hours tonight, but the battery (and the clouds) beat me, otherwise I would have taken double the subs and been able to discard some. (Still, if there are any "perfect" frames, I'll keep those and batch stack them later...).

Like the (failed) finderguider experiment, I'm still trying to persevere with the Synguider, and I'm sure it does work, but I think I may well end up following you down the PHD route sometime this year...

[msinclairinork]

Super Image Andy!

Just one sub!?!? Amazing!

I can't wait to get some guiding going! I still havn't managed to get all the peaces to gel yet.

Keep them coming!

Michael

[AndyUK]

Cheers Michael,

Yes - Just one sub... I'm amazed too!

The sad thing is I can't seem to get DSS to stack the others without running out or memory .

I think I'll leave it for the morning now (well, you know what I mean!), but as the other subs are pretty similar (and, for once, I actually have the full set of darks, flats and dark flats) I'm hoping I might be able to put something together that's better than this...

(Oh the joys of astrophotography and post processing !)

[MikeWilson]

Andy,

Can I get a copy of your data? I'd quite like to stack it and see how it comes out.

Best,

Mike

[ollypenrice]

Looking really promising!

Star shapes; it looks worse off centre so I would go for a) polar alignment, which does have to be good at ten minute subs. optical effect in the scope, lack of flattener etc. c) non orthogonal film plane. I would put money on alignment personally. If it happens again, just try a five minute sub.

There are halo effects round the stars. Probably a result of sharpening? If not, it might be the anti-aliasing routine but I don't know how you debayered.

In order to avoid messing up stars in processing, you can isloate them in a manner superbly explained by MartinB in his tutorials in the imaging tricks etc section. (Creating a Star Layer) Or you can buy Noels Actions plug in and use his instant Select Brighter Stars routine. If using Noel, you need to expand then feather his selection, as explained by Martin in his tutorial.

Onward!!

Olly

[AndyUK]

Cheers Olly! Polar alignment has always been my bête noire so I'm hoping it's that - I don't really want it to be either of the other two you mentioned... I'm probably showing my naivety but does an MN190 need a flattener? I hadn't budgeted for one as I thought it didn't need one, but if it does, then so be it...

The star haloes... yes, almost certainly due to a very quick and dirty unsharp mask. As it was "only" a single frame, this was really just a tester just to see what I might get out of the subs. I'd thought of using a blended high pass mask next time (assuming I can get the rest stacked - thanks for the offer Mike - I'll upload them for you sometime today!)

I'll certainly have another browse through Martin's tutorials regarding star layers (I've never used one before as I've never really had an image worthy of going through the effort!). As it happens I do have Noel's actions, but I've never used that particular feature to date...

(I think I may now be starting to progress to level 1 in the dark arts... )

[dc509]

I'm just about to start guided imaging and I hope I can come even close to the results you have achieved. Looking very good...#

d

[Psychobilly]

Excellent first "guided" light and a single sub "wowser"...

It might be just me (and i really need to see the original to check) but the left edge looks softer than the right .. was the camera sittign square to the focuser - how was it attached?

Andy have a good look at teh original and compare star shapes and sizes on the left and right hand edges top to boittom and compare them to the ones in the center..

Off to knit the kit up in the obs or i will never get it done...

Billy...

[AndyUK]

Cheers D... Thankfully there are some VERY knowledgeable people on here who can help us... Sadly I think my brain's reaching overload - It seems as though the more advice I get, the more I forget and the less I know! Still, if we get some clear nights, hopefully it'll start to come back again...

And also cheers Billy - It does appear that the top left has more "issues" than other areas (I meant to say left not right in the 1st thread...). The camera's attached via a Max DSLR Camera Adaptor and then straight into the moonlite - I'll watch out next time to ensure that the fit is "flush". If I still get the same effect, I'll then start worrying about whether the moonlite's been fitted "square" (Is there a way of testing that?)

[carastro]

That's excellent for a first guided image and only one sub and no darks, flats etc. You must be feeling very chuffed.

Looking forward to the stacked version with the darks and flats etc.

Carole

[ollypenrice]

The 190 needs no flattener. Sorry, I didn't know that was your scope. You are dead sure you got the Moonlite itself on flush?

10 mins at a metre does need good polar alignment, no doubt about it.

Olly

[AndyUK]

Thanks Carole - Yes, I'm very pleased with that frame... not least of which is the fact that, on the strength of it, I've just been given approval to buy a nice big leisure battery

Olly - I didn't fit the moonlite (I bought it with it already fitted), so I honestly don't know... Is there a way to check...? (I take it this wouldn't be a case of poor collimation?)

I must admit, my vote (and hope) is that this is still poor polar alignment - I know my current alignment technique is probably insufficient (I use polarfinder.exe and then adjust alt-az to get Polaris in the right place on the outer circle)

[Deneb]

not bad at all, let me see what I can pull from it, as it seems you've still got some stuff still to come out... Those star shapes, you may want to check the collimation on the scope.

Nadeem.

[Dave]

Nice one. A great start on auto-guiding.

[roundycat]

not sure about the star shapes but misalignment somewhere could be the reason. The depth of focus you have at high magnification is measured in the low microns, typically 5-10 so you really do need to get things straight.

As regards processing if you sharpen and find a halo (caused by sharpening - in other words it wasn't there before) then for heavens sake go back and start again. Once you have embedded those disastrous black halos everywhere there is no escape. No matter what you do you will not improve the picture. Look at Deneb's version, the halos are obvious even in the small picture.

You can use a layering technique to hide halos (if I recall, sharpen on a duplicate layer and set the blend mode to lighten) but all you are doing then is hiding a fault instead of addressing what actually caused it. Try unsharp mask at something like at Amount 50-100, Radius 2-3 and Threshold 12-18. If that shows halos anywhere back off the amount as that is the main contrast modifier.

Dennis

[AndyUK]

Thanks all...

Nadeem - I see what you mean about there being more to pull out! If/when I can get the rest stacked, I can see hours of work ahead to keep me occupied on those cloudy nights...

I'm hoping it IS the collimation as that will be the easiest of the lot to resolve - I'll check that first. The thought of potentially having to fiddle around reseating the focuser brings me out in a cold sweat.

Thanks Dennis - I now have a few things to try. I guess I'll need to allocate the next clear sky as a "testing" night.

With regards to processing, yep... I think the report would read "attempts to cut corners too many times and then comes a cropper". If/when I get the full set stacked, I'll see if I can create a star layer and/or use a blended high pass layer for sharpening and take it much more steadier...

[AndyUK]

I still haven't managed to get the full set into DSS yet , but I've had another go at processing that single sub (using a star mask this time to minimise the "halo" risk). Obviously those stars are still wonky (esp top left), but that'll have to be something for me to test next time....

[Psychobilly]

Nice improvement watch you dont clip the black leave room between the data hump and the left hand edge until the last stages of processing...

[AndyUK]

Thanks for the tip Billy - I thought the background looked a bit too dark...

[msinclairinork]

Yea the re-process looks a much better to me.

Can't wait to have a crack at this one day..one of my fav nebs!

Michael

[AndyUK]

Cheers Michael,

I think your ED80 will have a better FOV for this target - I really should have used my Equinox for this, but I've been desperate to get some practice in with the MN190 for nearly 8 weeks...

I'll be honest and admit that this was originally meant to be the cone nebula, but I got the NGC numbers mixed up on the GOTO and as I'd set everything up, I couldn't be bothered to move and set the guidecam up again... I'm glad I did now!

I also finally managed to get DSS to process the full stack (had to reboot), so here's the result of the full set - ISO400, 10 x 600s subs, 10 x 600s darks, 20 x flats, 20 flat darks, DSS and CS5. I went for a more "subtle" treatment on this version as it seemed there was more colour definition - I'd be very interested in anyone's views...!