Strange White Dots in Photos (Not Stars!!)

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Hi,

I have been refered to this forum by Robin from the Yahoo RSpec forum.

I recently purchased an Atik 16ic mono camera (secondhand) for spectroscopy work.  I have zero experience with CCD cameras - this is my first. 

While taking some images of stellar spectra I got a series of white dots in my images.  I am not sure what is causing these or how to get rid of them.
It was suggested to me that it may be electrical interferance external to the camera but I have no idea.  I turned the camera off for 15 min and when I resumed work they were gone. 
This has happened on two occasions now

A screenshot of the images is attached.  Does anyone have any idea what the dots are and how I can get rid of them? 

Thank you for any help.

Cheers,
Dan Gardiner