I do Astrophotography and we use Dark frames. Didn't know we could use the same technic here.
Gotta give it a try. I wonder if my Astrophotography software can process this image or not!
Look up “dark frame subtraction” and you’ll be able to filter out a lot of noise and sensor hot spots which will allow you to take very long exposures with high ISO. There are a lot of free astronomy related programs online to do this.