Table:
text: 1978 IMSA GT Championship season
Schedule
Schedule
Race Length_ Class_ Circuit Date_
24 Hours of Daytona 24 Hours All Daytona International Speedway February 4 February 5
12 Hours of Sebring 12 Hours All Sebring International Raceway March 18
6 Hours of Talladega 6 Hours All Talladega Superspeedway April 2
Camel GT Challenge mi (km) GTU Road Atlanta April 16
Camel GT Challenge mi (km) GTX/GTO Road Atlanta April 16
Monterey Triple Crown mi (km) GTX/GTO Laguna Seca Raceway April 30
Monterey Triple Crown 45 Minutes GTU Laguna Seca Raceway April 30
Hallett Grand Prix 1 Hour GTU Hallett Motor Racing Circuit May 7

text: 1978 IMSA GT Championship season
Schedule
Schedule
Race Length_ Class_ Circuit Date_
Hallett Grand Prix mi (km) GTX/GTO Hallett Motor Racing Circuit May 7
Coca-Cola 300 mi (km) GTX/GTO Lime Rock Park May 29
Coca-Cola 300 mi (km) GTU Lime Rock Park May 29
Pepsi Grand Prix mi (km) All Brainerd International Raceway June 18
Paul Revere 250 mi (km) All Daytona International Speedway July 4
Sears Point Grand Prix mi (km) GTX/GTO Sears Point International Raceway July 30
Sears Point Grand Prix mi (km) GTU Sears Point International Raceway July 30
G.I. Joe`s Grand Prix mi (km) GTX/GTO Portland International Raceway August 6
G.I. Joe`s Grand Prix 45 Minutes GTU Portland International Raceway August 6

Question: Which circuit of the 1978 IMSA GT Championship season was held for 1 hour on May 7th?