Hi guys. I'm getting to grips with a QSI683wsg and finding it a real mixture of good and puzzling. The biggest concern is the appearance of these odd short streaks of light in my darks and lights.
I attach 3 images. Two are from different darks and one is from a light - all 10 minute subs at -20C.
In the darks, you'll see random short streaks of light - not entirely linear, not columnar and not horizontal either. And you'll see the same sort of thing repeated in the light frame.
I've switched the whole imaging train across to another pier with a different USB hub, different PC and different power supply. These artifacts continue to appear.
They do not repeat in the same location. They appear to be randomised but persistent.
Perhaps a symptom of the same underlying problem, there seems to be an inordinate number of hot pixels as well.
Can anyone with KAF8300 experience (or QSI experience) throw any light on this?
Cosmic Rays - I believe they lead to premature baldness, obsessive-compulsive behavior like sitting alone in a shed in the middle of the night, severe depression like finding all your subs are rubbish after sitting in a shed all night, alcoholism (q.e.d) and other maladies. Ergo, it must be cosmic rays - the symptomology all fits.
However, just to throw a spanner in the works - it's in all subs going back for the past month that I've checked so far (can't see it in bias frames) all the time. Either the sun has really decided we need a working over out here, or there is something else wrong. I just started another run of calibration frames and the first one out (just 5 minutes of dark) showed it.
So, sadly because it is starting to sound expensive, I fear the answer lies elsewhere.
Hi Peter,
I take it that you're not showing a full frame?
If that's the case and you are showing a tiny part of one frame -
then they are caused by natural radioactive decay or cosmic rays.
They are normal & it's part of the reason why you need to take at least 12 dark frames to get rid of them with a master dark frame.
Guys, I don't question that cosmic rays can and do occasionally zap a sub or two. But my instinct says that can't be what's happening here because:
(a) I have 2 other CCDs working here and neither is showing this problem; and
(b) these flashes are not straight-line. My simplistic understanding is that Cosmic Rays would produce a straight flash whereas these are bent, curved, non-linear.
Guys, I don't question that cosmic rays can and do occasionally zap a sub or two. But my instinct says that can't be what's happening here because:
(a) I have 2 other CCDs working here and neither is showing this problem; and
(b) these flashes are not straight-line. My simplistic understanding is that Cosmic Rays would produce a straight flash whereas these are bent, curved, non-linear.
Peter
Cosmic ray hits can be bent too. I get them all the time on my subs in my QSI. I don't see anything in your images that would lead me to think otherwise.
Guys, I don't question that cosmic rays can and do occasionally zap a sub or two. But my instinct says that can't be what's happening here because:
(a) I have 2 other CCDs working here and neither is showing this problem; and
(b) these flashes are not straight-line. My simplistic understanding is that Cosmic Rays would produce a straight flash whereas these are bent, curved, non-linear.
Peter
Some cameras are more prone to then than others.
My SBIG cameras seem to get more. I think it is from decay events occurring in the cover glass.
I remember reading that most probably are not actual cosmic rays but from local radioactive decay. These could be low or high energy.
I use to have very few when I lived in Moree which is on the western plains of NSW. I now live in the ranges on a big lump of granite and have many more ray hits. Whether it is the increased altitude or the natural radiation from the granite I'm not sure.
Curved or forked rays can be from decay events occurring in the glass or CCD.
