I mentioned this in the response to your last question, but it is definitely not a clear cut path. That said, if you do a master’s degree and raise your GRE scores while doing a good research project for your master’s thesis, it will definitely help your chances of admissions, but there is nothing as clear-cut as the path from a community college into a four-year school. Graduate programs, especially at the UCs are extremely selective and don’t have any mandate to show the same kind of preference for in-state students that undergraduate programs do.

There aren’t really any “medium quality” places to do a PhD in astronomy in California, but if the issue is just that you don’t want to move all the way across the country, and you can’t get admitted to a UC school or Stanford or Caltech, then consider the Arizona schools (U of A is ranked comparably to the UCs, while ASU is still quite good, but a lot easier to get admitted to). They’re probably not too much further from your home than some parts of California.

Really at the grad level, if your looking to go all the way to Ph.D, its all about your resume and the research you conduct. If you can get published or assist on research that is published, who cares where you went. There is a good amount of favoritism towards UC’s, but that is generally because they are higher cost and have bigger, more recognizable names (sports has a lot to do with this). There are some great CSU’s up and down the state and when all is said and done, you will really only be remembered for where you got your Ph. D. So if you get your MA or MS at a CSU, remember its about your research completed and final degree when people pass judgment on you. Oh, and try to mix things up as far as where you got your BS, MS and Ph.D…it is frowned upon to have degrees from the same place. Diversify!