M57 not stacked in DSS

[Russe]

Hi guys,

don't know what's wrong. Used to work with previously made 20s pics on an Alt-Az mount, but this time I'm stumped.

Got my HEQ5 a month ago and finally tried it out for 60s pics of M57. As I'm still in the process of starting to become an astrophotographer I have a very meager setup, so don't shoot me.

My camera is a Phillips 880 with LX mod, my scope is a 127 Mak and I don't guide (yet ... one after another). That very same evening I had for the first time successfully (more or less) polar aligned the mount...

The setup gives me plenty to play with and is a lot of fun for now.

Please give me an idea of, why I'm not getting my pics stacked.

MasterOffset_ISO0.tif

MasterDark_ISO0_0s.tif

MasterFlat_ISO0.tif

[Russe]

the message displayed reads: Only one frame will be stacked. You should change the star detection threshold to detect more stars and help ...

I've got the threshold at 2%.

[nmoushon]

Its probably because DSS can't find enough bright stars to align all the images too. It happens a lot with shorter exposures.

[Russe]

how can I stack those pics then, any idea?

[nmoushon]

I know you can do it manually in PS but I don't know how. Sorry.

[Freddie]

How many stars is DSS saying it is detecting? It's going to need to see at least 9. Nebulosity allows you to pick the point to align for stacking, is a nice bit of software and relatively low cost if you don't have it. You can try it out for free (with lines on the final image) before buying.

[NickK]

I think the issue is that the stars are difficult to detect:

As you can see from this the stars aren't really standing out from the background (I see that these 16 bit so there's plenty of space). More time on target will help this.

You could use either nebulosity to manually target the stars (or in PI then use dynamic alignment).

[NickK]

Just quickly - one way to help on this is to deconvolve using the few detectable stars - this will modify the image and make the peaks higher and hence allow easier detection.

[dph1nm]

Isn't there a comet-align feature in DSS which allows you to stack on a particular object (which could, I guess, be the one bright star visible in the images)? No good if you have image rotation of course.

NigelM

[Russe]

@Nick how did you produce that pic?

[Russe]

Deconvolve?

[NickK]

The plot is made using the PixInsight 3D plot function.

Thinking a bit more - the deconvolution would cause issues with the white pixel noise.

Here's an example: http://stargazerslounge.com/topic/157001-using-dynamic-psf-to-add-some-clarity/

[Russe]

Finally forced Reg6 to stack the lot after choosing alignment points myself.

But, I couldn't load my master flats-darks-bias from DSS into Reg6 as they aren't bmp png fit but tif...

I'm losing the will to live...

So I've loaded the Reg6 file into DSS to combine it with my flats-darks-bias.

I find that the 2nd pic has more noise than the first, albeit it's darker.

test2proc.TIF

[Russe]

By the by, 94x 30s exposures unguided with an LX modded SPC880.

[Russe]

this is the 45s version

test1 proc.TIF

[NickK]

Hehe either you spend the time in the capture or the time in the process.. eitherway AP takes time and energy.. I'll have a play with that stack later and see what we can get out of it

[Russe]

Thanks *thumbs up!

[NickK]

You certainly have data in there - although the field flatness, tracking errors etc are really sticking their knives in.

I've used the same technique as I used on my m57 - the difference is that the stars show very different profiles (ie they elongate in different ways).

[Russe]

Yeah, tracking error is bugging. No matter how well you align, it's always a bit off. I'm not good with polar alignment as well.. Need to figure out how to run EQMOD for the HEQ5 to get more accurate...