
Dark current (top), which Hallas described in last month’s column, introduces electronic noise into astroimages taken with CCD cameras. Luckily, it’s easy to remove with software. The result (bottom) speaks for itself.
Tony Hallas
In my initial column last month, I talked about why I prefer charge-coupled device (CCD) cameras over hand-held digital ones. This month, I continue my discussion of CCD imaging by examining something called the “signal-to-noise ratio.”