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Astro is a contract bridge bidding convention used to intervene over an opponent's one notrump (1NT) 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 〔In the description of competitive bidding, players are referred to as either the Opener, the Intervenor (the opponent who makes his side’s first bid, the Responder (partner of the Opener) or the Advancer (partner of the Intervenor).〕 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: : *2 shows at least 5-4 or 4-5 length in hearts and a minor suit, and : *2 shows at least 5-4 or 4-5 length in spades and another suit. When playing Astro but not holding the prescribed two-suited hand, the following calls are available over the 1NT opening by the opponents: : *an overcall of 2 or 2 is natural showing a single-suited hand : *Double is for penalties ==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: : *Pass when weak and holding six cards in the minor bid by the Intervenor, or : *Raise the anchor major: (a) to the 2 level with at least 3-card support, preferably with an honour, and no game intentions, or (b) raise to the 3 level with at least 4-card support and inviting game, cognizant of vulnerability and the point range of the 1NT opening, or (c) raise to the 4 level with at least 4-card support for game-try, or : *Bid an artificial and forcing 2NT to show some support in the anchor suit, game interest but no potential to bid further, or : *Bid a new suit take-out or new suit jump, to show a 6-card or longer suit, or : *Make a negative bid of 2 in the neutral suit to indicate having no other options, usually less than 3 cards headed by an honour in the anchor suit and at least a doubleton in the neutral suit. Intervenor rebids include: : *Pass after a neutral response with five cards in the neutral suit, or : *a bid of the anchor major to show 5 cards, or : *a bid of the second suit at the 3-level to show 6 cards and good playing strength. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Astro convention」の詳細全文を読む スポンサード リンク
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