coloured lines help

[ako]

Hello,

attached is 2 hours worth of 5min subs of m109. ive done a rough process, can someone tell me what the streaked colored lines are?

are they noise and would darks remove them? i dont understand why they are lines as guiding seems good on the stars? something during stacking?

camera is a qhy9c, cooled to -20

would appreciate any help.

many thanks matt

[Merlin66]

It's interesting that they are all RBG colours....could be hot pixels

Did you take the associated darks?

Have you applied them yet?

[ako]

no i dont yet have a set of 5 min darks at -20, will hav to do some. if they are hot pixels there are loads of them? and why do they appear like trails?

[Merlin66]

Hmmm

Would appear so....

The darks should kill off most if not all of them.

[themos]

The guiding may be good but it's not perfect. As a result the fov "creeps" along in a certain direction. Registering and stacking then sweeps the objects back in their proper place. But the hot pixels are not from the sky but from the camera, and so this "sweeping back" puts them in new positions for each member of the stack. Result: coloured streaks.

Darks should sort them out, or a cosmetic tool to just replace single outlier pixels by the median of the surrounding ones.

[jgs001]

If you stack with a statistical mechanism it may deal with the hot pixels. If using DSS, then try using Median Kappa Sigma.

[ako]

thanks for the replies, yes was stacked in DSS. i have a set of 5min darks at -30, will try that.

is it normal for so many hot pixels like this, is there a problem with the ccd?

[themos]

Before you use darks that may be wrong for your subs, use the Cosmetic tab of the Stacking Parameters dialog

and tick the Detect and Clean Hot Pixels, and the test on first frame.

[martin_h]

is it normal for so many hot pixels like this, is there a problem with the ccd?

You should see mine! and thats just a crop from the centre!

[ako]

When get back 2comp I'll give it s go and post results. As long as it's something that can be fixed and it isn't dreaded equiptment issues.

Many thanks for the speedy replys

[ako]

i have stacked all the frames again with the cosmetic setting as above, and ......drum roll......

we have success, ive only done a very rough process but here is a results with a similar crop.

many many thanks, i thought i had a duff ccd for a while.

:hello2:

[Merlin66]

Just glad we could help!

onwards and upwards......