It depends on what you mean by "part-year resident." or if you are a nonresident who was in NY temporarily for some reason.
Generally speaking, your retirement income is potentially only taxable if you were a resident of New York.
If you were a part-year resident of New York, as in you moved into or out of New York during the tax year, then a portion of your pension received as a resident would be taxable.
If you were a NY nonresident, then you do not pay any NY tax, as no state is allowed to tax a nonresident on pension income.
For more information, please see Form IT-230-I 2019 Instructions.
