Yes.

In fact, it is quite common for students to take the lecture course first and the lab course at a later time, when they can fit it into their schedules. The material covered in the lecture course is available from a public website, so you can use that as a reference in lab even when you are no longer registered in the lecture.

Note: Due to the continuing cutbacks in our state budget, the astronomy lab course is not being offered this semester and might not be offered in the near future.