PLT OF A PIPER PA32 ENTERED CLASS D AIRSPACE WITHOUT OBTAINING CLRNC FROM TWR DUE TO A NEWLY ESTABLISHED TWR AND RPTR'S APCH PLATE DID NOT REFLECT THE CHANGE.

Narrative

WE WERE ENRTE FROM ALB; NM; AT XA45 IN THE MORNING; ENRTE TO KEARNEY; NE. WE WERE MONITORING WX CONDITIONS ON FLT WATCH AND HAD TALKED TO THEM. THE WX HAD SEVERE ICING IN NEBRASKA. WE HAD NOT PLANNED ON STOPPING IN GARDEN CITY; BUT CHANGED OUR MINDS TO REGROUP OUR PLANS BECAUSE OF WX AT OUR DEST. I LOOKED UP THE APCH PLATE FOR GARDEN CITY; IT HAD NO CHANGE FOR A TWR OR FREQ CHANGE. WE WERE ON 123.0 WHICH WAS UNICOM. I RPTED WHEN WE WERE ABOUT 10 MI OUT. NO ONE EVER SAID ANYTHING. I RPTED 2 MORE TIMES BECAUSE I SAW 2 OTHER ACFT IN THE PATTERN. I CROSSED OVER THE VOR AND TURNED DOWNWIND FOR RWY 17. I THEN WAS CONTACTED BY TWR AND TOLD TO GO TO 118.15; WHICH I DID. I CONTACTED TWR AT THAT TIME. I HAD NO IDEA THAT A TWR HAD BEEN ACTIVATED A COUPLE WKS BEFORE. IT WASN'T IN MY APCH PLATES. I CAUSED NO DANGER TO ANYONE. IT WAS EXCELLENT VFR CONDITIONS -- WE HAD BOTH ACFT IN SIGHT. I HAD BEEN IN GARDEN CITY SEVERAL TIMES AND HAD NO IDEA ABOUT A NEW TWR. MY CONCERN ON THIS SIT IS THAT IF THE TWR IS NEW; WHY WOULDN'T YOU MONITOR THE 123.0 FOR A FEW WKS. THEY WOULD HAVE BEEN ABLE TO TELL ME WAY IN ADVANCE OF ENTERING TFC PATTERN.