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_28081876_6 (original_air_date VARCHAR, us_viewers__millions_ VARCHAR)
### Question:
When was originally aired the episode with an audience of 1.57 million us viewers?
### Answer:
SELECT original_air_date FROM table_28081876_6 WHERE us_viewers__millions_ = "1.57"