diff --git a/csst_ifs_sim/csst_ifs_sim.py b/csst_ifs_sim/csst_ifs_sim.py
index 0c04edf1e1a5afb37a3f915f810bfe2ed3e891ab..0203678a26f341fa076f0298bfd3e10399531dd7 100644
--- a/csst_ifs_sim/csst_ifs_sim.py
+++ b/csst_ifs_sim/csst_ifs_sim.py
@@ -1140,7 +1140,8 @@ class IFSsimulator():
     
         # get solar position
         dt = datetime.fromisoformat(time)
-        jd = julian.to_jd(dt, fmt='jd')
+        jd =time2jd(dt)
+        ##jd = julian.to_jd(dt, fmt='jd')
         
         t = Time(jd, format='jd', scale='utc')
     
@@ -4496,8 +4497,8 @@ class IFSsimulator():
 
                 ##########################################
             ########################################################################
-            self.dt=julian.from_jd(exptime_start_jd, fmt='jd')
-            
+            #self.dt=julian.from_jd(exptime_start_jd, fmt='jd')
+            self.dt=jd2time(exptime_start_jd)
             ##################################################################
 
             self.TianCe_day=self.dt.strftime("%Y-%m-%d") ###str(self.dt.year)+'-'+str(self.dt.month)+'-'+str(self.dt.day)