Thanks. It is an f/1.4 lens and I shot at f/2.2. When shooting stars, it is normal practice to stop down a bit from wide-open.
I was always under the impression that the more light you can allow the better..
The more light that is allowed to hit the sensor usually means you can reduce the length of exposure needed which also means less noise, and a larger aperture means that you can capture more detail in that shorter amount of time.