M13 bugging me in DSS

[Spoon]

evening,

i just came back from an astronomy holiday and i have some pictures subs of M13, but when put through Deep Sky Stacker, it either says that only one of the frames could be processed or the image turns out like this, i think that without the trails it would be an alright (not GOOD by any stretch). i have attatched the pic, please help its really annoying me!

thanks, Cam

[keyser187]

i usually use a diff ref frame by right clicking on a sub with a highish score and selecting use as refrence frame, i try a few till i get it to stack.

[Spoon]

will try now and let you know

[Zakalwe]

If the stars are trailing then DSS might not stack them.

You can also check how many stars DSS is picking up....aim for 50-100.

Work on your polar alignment to prevent trailing...you should be able to get 2 minutes without trailing in the majority of sub-exposures.

Here's a good tutorial on DSS:

though the old computer adage of GIGO applies...Garbage In = Garbage Out

[Spoon]

i have 10mins 30 secs altogether of light frames, all 30sec subs. i cant figure out my CG5 though so i cant really polar align, thats annoying too

[Spoon]

i usually use a diff ref frame by right clicking on a sub with a highish score and selecting use as refrence frame, i try a few till i get it to stack.

tried it, same thing came up, the score is 47.86 and DSS can find 86 stars

[lensman57]

Hi,

evening,

i just came back from an astronomy holiday and i have some pictures subs of M13, but when put through Deep Sky Stacker, it either says that only one of the frames could be processed or the image turns out like this, i think that without the trails it would be an alright (not GOOD by any stretch). i have attatched the pic, please help its really annoying me!

thanks, Cam

Hi,

This usually happenes when DSS can not find sharp stars to use for alignment. It could be bad focus, star trails, bad PA or a combination of all. Try the manual setting of a reference frame as suggested by others to fool the DSS and reduce the star detection threshold in the adavance section of the regitering process dialog to get a star count above 8, below this level DSS will not stack. Hope you can sort it out.

A.G

[JamesF]

My experience is also that if you have badly-shaped stars in the image, DSS will be unhappy about stacking. I've fallen foul of this in the past and sadly just had to abandon the data, but if you can find one frame with decent stars it may be possible to recover something. I think DSS assumes that if something isn't very close to round then it isn't a star, and if there aren't enough stars in an image then it can't stack them.

I don't know what the score that DSS assigns to each frame actually means, but 40-ish strikes me as quite low. For my reference image for this:

http://stargazerslounge.com/topic/191682-bloated-stars-and-other-problems/

I think I had a score of over 950, but I'd guess that is at a rather longer focal length than you used for your image.

James