small stack goes all in

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PokerStars No-Limit Hold'em, $10 BB (9 handed) FTR converter on zerodivide.cx

UTG+1 ($1045)
MP1 ($2200.65)
MP2 ($995)
MP3 ($1553.50)
CO ($253.70)
Button ($392)
SB ($1005)
BB ($207)
Hero ($1302.85)

Preflop: Hero is UTG with A[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img].
<font color="#CC3333">Hero raises to $20</font>, <font color="#666666">6 folds</font>, SB calls $15, BB calls $10.

Flop: ($60) 5[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, BB checks, <font color="#CC3333">Hero bets $30</font>, SB calls $30, <font color="#CC3333">BB raises to $187</font>

At this point I put the small stack on some kind of ace, and I don't have much idea about the big stack behind.

I need a thinking process here. Folding is not an option, but do I call or raise, and why?