Astro convention


Astro is a contract bridge bidding convention used to intervene over an opponent's one notrump opening bid. The name is derived from the initials of the surnames of its inventors - Paul Allinger, Roger Stern and Lawrence Rosler.
Astro employs a 2-level overcall in a minor suit when holds an unbalanced hand with at least nine cards in two suits, at least one of which is a major; hand strength should be unsuitable for, or not strong enough for a penalty double, typically no more than 15 points. The minor suit overcalls are artificial and carry the following meanings:
When playing Astro but not holding the prescribed two-suited hand, the following calls are available over the 1NT opening by the opponents:

Subsequent bidding

For purposes of subsequent bidding, the major suit indicated by the Astro Intervenor is termed the “anchor major”; the cheapest unbid suit is called the "neutral" suit.
Depending upon action taken by the responder to the 1NT opener, Advancer may:
Intervenor rebids include:

Variations

In the following variations of Astro, the overcalls indicate more specific information about suit combinations:

Modified Astro

Pinpoint Astro

Roth-Stone Astro

Defense against Astro

Responder to the 1NT opener may:

Alternative conventions

Several other bidding conventions use a variety of schemes to compete against a 1NT opening; these include: Aspro, Asptro, Brozel, Cappelletti, DONT, Landy and Ripstra.