Astro is a method of competing against an opponent's 1NT opening bid for 2-suited hands.
An overcall of 2 shows at least 5/4 or 4/5 shape in hearts and a minor,
2 shows at least 5/4 or 4/5 shape in spades and any 1 other suit.
HCP range approximately 9-14. Any other bid is natural.

The Astro Overcalls are:

East	South	Shows
1NT	2	At least 4 hearts with unknown minor
	2	At least 4 spades with unknown 2nd suit

Please note
1: The longer suit can be either way round, ie., at least 9 cards in your 2 suits
2: One of the Astro bidder's major suits is always known
3: All direct game calls are sign off

More Frequent Responses to Astro

East	South	West	North	Shows
1NT	2	Pass	2	Denies 3 cards in the known major (hearts)
			2	At least 3 cards in the known major (hearts)
	2	Pass	2	Denies 3 cards in the known major (spades)
			2	At least 3 cards in the known major (spades)

Less Frequently Used Responses

East	South	West	North	Shows
1NT	2/	Pass	2/3	6+spades/clubs, denies 3 of known major (NF)
			2NT	11+HCP would like to find out what partner's other suit is (forcing)
			3/3	good 6-card suit, good 3 of other minor, denies 3 of known major, (invitational)
			3/3	Jump in any suit is natural and invites game. Here it invites game in the known major Partner should pass if minimum

Please note

1: If the Astro overcall is doubled, responder may:
(a) Pass to show at least 4 cards in the suit doubled.    (b) Make a normal response.

2: If opponent bids over the Astro overcall, the Astro responses have the same meanings as far as possible.