What is this?

[shaunster]

Recently at the start of my imaging sessions I have been having some problems with black stuff appearing on my subs, it slowly disappears as the night goes on getting less and less intrusive with time but it can take up to 60mins for it to go.

Scope is only a little frac, a WO zenithstar 70 and camera is an atik 383l+ using a TV trf2008 flattener, all housed in a ROR obsy. I never had this problem so bad until the last few nights, all over summer I used this setup and this did not happen.

Any ideas what it is? I think it may be related to heat? Not sure though.. so any help is much appreciated.

Attached is one sub, crudely stretched to show what I mean.

[Ben Ritchie]

Looks like either dewing or icing to me - if the air is humid then it's possible for a CCD to dew up or even ice up as the cooler kicks in and the temperature of the CCD window drops.

There's sometimes (...usually...?) desiccant to dry it up, but it may need recharging - with the SBIG CCDs there was a little desiccant cannister that you took out and baked in the oven for 30 minutes...

[shaunster]

There is a desiccant chamber, I have not changed it since I got the camera so could be that?

I have the cooler set to -25.

[Catanonia]

it is definately icing of the chip especially if it calms down over the night

[shaunster]

Atik are sending me some new desiccant tablets

[fwm891]

I've just got an Atik 383L+ so would like to know how you get on with this please...

Looks like ice tendrels but I thought they would appear 'more focused' being on the CCD window?

[ollypenrice]

No, I agree that it looks like icing. It is way out of focus, remember. Does the 383 have any window heating option? My 4000s do but it has to be launched from the programme files (or something) and not from the Artemis Capture screen. I have only used it once.

Olly

[shaunster]

Ive never had it before and the desiccant looked really pale, from what I have been reading that means its exhausted so hopefully it should sort it out.