I just bougt the ASI294MC and the first thing I did was to take some bias frames. I downloaded the frames via USB3 port on to my windows 10 PC with SGPro. Gain was 120, temp -5°C. When opening the frames in Pixinsight and applying the STF (screen Transfer Function-stretch) Some brought horizontal banding becomes visible on all of the bias frames but not always on the same place in the image. So the sensor or cooling can't be blamed. To take a closer look I made 30 Bias frames and integrated them.
After integration I cropped from the middle a 2048 x 2048 square. From one of the bias frames I did the same crop. Then I subtracted from the cropped bias frame the cropped integrated bias frame and did an FFT (fast fourier transform) using the FFT module from PI. The result shows me an image with a vertical bright line in the middle. If the pixel distribution of the bias frame would have been Gaussian I would have only a bright point in the middle of the image. The vertical line seems to tell that there is a high frequency component in the downloaded bias frames. Maybe a badly shielded clock frequency???
The method used is described by QSI in their article: Interpreting Fourier transforms: link: http://www.qsimaging.com/ccd_noise_interpret_ffts.html
Can you tell me what your interpretation is of this phenomenon?
Attached the FFT and one of the bias frames.