Astro

        Astro is a nice system of defense against 1NT openings. Here's how it works:

(1NT) — 2:     Shows hearts and a minor. (1NT) — 2:     Shows spades and a lower suit.

Both overcalls show at least 5-4 (or 4-5) in the two suits. The 2 and 2 overcalls retain their traditional meanings, and double is for penalty. With a long minor suit, you must choose between passing and overcalling at the 3-level.

        Responding to Astro.    Responder has the following choices after an Astro overcall:

(1NT) — 2 — (Pass) — 2:     Shows 3-card heart support. 2:     Asks overcaller to bid his second suit. 2NT:     Shows interest in game (forcing).

After the 2 response, overcaller has the following bids available:

(1NT) — 2 — 2 — Pass:     Shows diamonds. 2:     Shows 5 hearts. 2:     Shows 3 spades     (in case responder has 5). 3:     Shows 5 clubs.

Responder can bid 2NT after a 2 or 2 bid to ask for overcaller's minor.