diff --git a/db/xmet.sql b/db/xmet.sql
index ce1c778..397ac17 100644
--- a/db/xmet.sql
+++ b/db/xmet.sql
@@ -113,6 +113,8 @@ create table xmet_sounding (
 );
 
 create index xmet_sounding_station_idx                     on xmet_sounding (station);
+create index xmet_sounding_timestamp_observed_idx          on xmet_sounding (timestamp_observed);
+create index xmet_sounding_timestamp_released_idx          on xmet_sounding (timestamp_released);
 create index xmet_sounding_timestamp_observed_released_idx on xmet_sounding (timestamp_observed, timestamp_released);
 
 select AddGeometryColumn('xmet_sounding', 'location', 4326, 'POINT'),