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_52 ( diameter__km_ INTEGER, longitude VARCHAR, year_named VARCHAR )

### Question ###
What is the Diameter (km) of the Valle with a Longitude of 152.5e named before 1997?

### Accurate SQL ###

SELECT MAX(diameter__km_) FROM table_name_52 WHERE longitude = "152.5e" AND year_named < 1997