Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_26 (year__ceremony_ VARCHAR, category VARCHAR, actor_actress VARCHAR)

### Question ###
What is the year when sigourney weaver was nominated for best actress?

### Accurate SQL ###

SELECT year__ceremony_ FROM table_name_26 WHERE category = "best actress" AND actor_actress = "sigourney weaver"