"rain" dark noise?!

[rogerg]

Hi all,

Can anyone advise on what causes this kind of noise? The length of the "rain" increases with exposure time. 1s shows no "trails", 300s shows longer trails. This example is 180s.

This is a single 180s dark frame.

ST10-XME.

Regards,
Roger.

[RB]

Did you check the weather Roger?

:question:

[glend]

Heat. Camera sensors need to be cooled. The longer the exposure the more heat is generated. You may be able to subtract it with dark calibration.

[rogerg]

Is that a sarcastic comment or am I missing the meaning? :)



This is the dark. Normally I see point like noise on darks and cosmic rays, not vertical lines that get shorter towards the top of the image. Are you suggesting this a normal dark frame for some cameras?

[billdan]

Looks like the TEC cooler is not working. Attached is a crop of a single 300sec dark from my QHY12.

Bill

[rogerg]

That is more what I am used to from my other cameras :thumbsup: Would be a pain if the cooler has died. It is reporting a temperature and power as though it's working.

[billdan]

You may have to email SBIG and attach the image and see what they say.

EDIT: Wonder if it is noise on the USB cable?

[rogerg]

I've posted a thread.



We have other issues with noise on the USB cable ;) but i"m hesitant to blame this on it .... because it's so consistent, but I could be wrong.

[PeterM]

Have you changed anything in the chain that delivers power to the camera? Month ago at Leyburn I used a cig lighter board with multiple sockets it allowed me run one wire to batteries and plug everything in at scope but it introduced very odd patterns in my ccd image. Also I had an issue some time ago I traced to the usb cable. I bought a Lindy powered usb and that fixed it.

[rogerg]

Thanks Peter. It certainly would be worth connecting it directly to a laptop/pc with a short different USB cable. I'll see if I can arrange that.