Astro Defense to 1NT opening
              ----------------------------

2C =  at least 5-4 or 4-5 in hearts and a minor.  
      With three card or better support, advancer bids hearts.
      Without such support, advancer bids
         * pass with long clubs
         * 2D to ask for the minor. Overcaller passes with 
           diamonds or bids 2H with clubs. With a strong hand
           overcaller can bid naturally 3C or 3D.
         * 2S, 3C or 3D to show a good hand with the bid suit.
      
2D =  at least 5-4 or 4-5 in spades and another suit (including hearts)
      With three card or better support, advancer bids spades.
      Without such support, advancer bids
         * pass with long diamonds
         * 2H to ask for the other suit. Overcaller passes with 
           hearts or bids 2S with a minor (2N again asks for the 
           suit). With a strong hand overcaller can bid naturally
           3C, 3D or 3H.  
         * 3C, 3D or 3H to show a good hand with the bid suit.
      
2H/S= only hearts or only spades

2N =  both minors 

X  =  penalty.

Over 2C thru 2S overcalls  advancer can use 2N as a game-inviting
inquiry, so 
   (1N) 2C (p) 2N;  3C or 3D  = weak with that minor 
                    3H or 3S  = strong with clubs (H) and diamonds (S)

   (1N) 2D (p) 2N;  3C, 3D, 3H= weak with that suit 
                    3S, 3N, 4C= strong with diamonds (S), hearts (N) 
                                and clubs (C)

   (1N) 2H (p) 2N;  you can use your regular devices over a  
   (1N) 2S (p) 2N;  weak two here. 
                  
Over interference over a 2C or 2D overcall, advancer can 
   * pass a double to ask for the suit.
   * redouble to play.
   * double a lower suit as takeout. 
   * double 2S (after 1N-2C-2S) as penalty. 


The advantages of this defense are 1) you retain the use of the 
penalty double, 2) you can bid 2H and 2S naturally (and preemptively),
and 3) you can show all two suiters with a major easily.