...If you were a resident for only part of 2009, you are subject to
New York State tax on all income you received while you were a
resident of the state and on income you received from New York
sources while you were a nonresident.

To compute the amount of tax due, use Form IT-203, Nonresident and
Part-Year Resident Income Tax Return. You will compute a base tax as
if you were a full-year resident, then determine the percentage of your
income that is subject to New York State tax and the amount of tax
apportioned to New York State...