Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
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?
### Answer:
SELECT MAX(diameter__km_) FROM table_name_52 WHERE longitude = "152.5e" AND year_named < 1997