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_16 (ngc_number INTEGER, constellation VARCHAR)
### Question:
What is the sum of NGC numbers for Constellation vela?
### Answer:
SELECT SUM(ngc_number) FROM table_name_16 WHERE constellation = "vela"