CMOS instead of Chopper?

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#581393
Eliot Hall
Participant

Great project – Robin is a pioneer.

Taking inspiration Emil Kraaikamp deep sky images using CMOS cameras at fast(ish) frame rates using big scopes – I wonder if the chopper could be replaced with a CMOS camera.  If the camera was run at 60Hz (twice as fast as the Crab’s pulse rate).  All even numbered frames were stacked together and the same with odd numbered frames.  Then the two images would be subtracted from each other.  Only the light from the pulsar would remain – proving the pulse rate?

It would rely on a bit of luck with the timing – if the capture started at the maxima or minima there would be no difference in the pulsar’s brightness between the frames.  Also I’m not sure you could trust the camera to run at a constant speed and not drop frames whilst capturing.  Finally whilst the read noise very low on CMOS chips I’m not sure there would be enough flux to overcome it.

With all this thinking I might need a lie down…