diff --git a/csst_dfs_api/common/ephem.py b/csst_dfs_api/common/ephem.py
index 3b7a2c453de72faf426834159c44d02c3c948444..4eebd9dfc76e11521ee73155b5c10985fe33e361 100644
--- a/csst_dfs_api/common/ephem.py
+++ b/csst_dfs_api/common/ephem.py
@@ -1,7 +1,18 @@
+from .delegate import Delegate
 class EphemSearchApi(object):
     def __init__(self):
-        pass
+        self.module = Delegate().load(sub_module = "common")
+        self.stub = getattr(self.module, "EphemSearchApi")()
     
-    def search(self, ra: float, dec: float, radius: float, limit: int):
-        pass
+    def gaia_query(self, ra: float, dec: float, radius: float, mag: float, limit: int = 1000):
+        ''' retivial GAIA DR 2
+            args:
+                ra:  in deg
+                dec:  in deg
+                radius:  in deg
+                mag:  
+                limit: limits on the number of returns
+            return: a dict as {success: true, totalCount: 100, records:[.....]}
+        ''' 
+        return self.stub.gaia_query(ra, dec, radius, mag, limit)    
 
diff --git a/examples/ifs_rss_pipeline.py b/examples/ifs_rss_pipeline.py
index c21cb3e9cc1cb579a1dabb4cd98884ab857a53ee..e0f7a6f59715d378fb7d46ab42d84d0cad948e9f 100644
--- a/examples/ifs_rss_pipeline.py
+++ b/examples/ifs_rss_pipeline.py
@@ -23,9 +23,11 @@ class RSS(object):
         try:
             self.raw = self.fitsApi.find(file_name=file_name)
             self.raw = self.raw[0] if self.raw else None
-            log.info("find raw fits: %s,%s"%(self.raw["id"], self.raw["filename"]))
             if self.raw is None:
                 log.error('raw %s not found' %(file_name,))
+            else:
+                log.info("find raw fits: %s,%s"%(self.raw["id"], self.raw["filename"]))
+
         except Exception as e:
             log.error('raw %s not found' %(file_name,),e)
 
@@ -33,10 +35,11 @@ class RSS(object):
         try:
             self.bias = self.refFitsApi.find(file_name=file_name, ref_type=RefFitsApi.REF_FITS_BIAS)
             self.bias = self.bias[0] if self.bias else None
-            log.info("find ref bias fits: %s,%s"%(self.bias["id"], self.bias["filename"]))
-
+            
             if self.bias is None:
                 log.error('bias %s not found' %(file_name,))
+            else:
+                log.info("find ref bias fits: %s,%s"%(self.bias["id"], self.bias["filename"]))
         except Exception as e:
             log.error('bias %s not found' %(file_name,),e)
 
@@ -44,10 +47,11 @@ class RSS(object):
         try:
             self.flat = self.refFitsApi.find(file_name=file_name, ref_type=RefFitsApi.REF_FITS_FLAT)
             self.flat = self.flat[0] if self.flat else None
-            log.info("find ref flat fits: %s,%s"%(self.flat["id"], self.flat["filename"]))
-
+            
             if self.flat is None:
                 log.error('flat %s not found' %(file_name,))
+            else:
+                log.info("find ref flat fits: %s,%s"%(self.flat["id"], self.flat["filename"]))
         except Exception as e:
             log.error('flat %s not found' %(file_name,),e)
 
@@ -55,10 +59,11 @@ class RSS(object):
         try:
             self.arc = self.refFitsApi.find(file_name=file_name, ref_type=RefFitsApi.REF_FITS_ARC)
             self.arc = self.arc[0] if self.arc else None
-            log.info("find ref arc fits: %s,%s"%(self.arc["id"], self.arc["filename"]))
 
             if self.arc is None:
                 log.error('arc %s not found' %(file_name,))
+            else:
+                log.info("find ref arc fits: %s,%s"%(self.arc["id"], self.arc["filename"]))
         except Exception as e:
             log.error('arc %s not found' %(file_name,),e)
 
@@ -66,17 +71,30 @@ class RSS(object):
         try:
             self.sky = self.refFitsApi.find(file_name=file_name, ref_type=RefFitsApi.REF_FITS_SKY)
             self.sky = self.sky[0] if self.sky else None
-            log.info("find ref sky fits: %s,%s"%(self.sky["id"], self.sky["filename"]))
 
             if self.sky is None:
                 log.error('sky %s not found' %(file_name,))
+            else:
+                log.info("find ref sky fits: %s,%s"%(self.sky["id"], self.sky["filename"]))
         except Exception as e:
             log.error('sky %s not found' %(file_name,),e)
 
     def makecube(self, outfile):
 
-        hdul_raw = fits.open(os.path.join(self.root_dir, self.raw['file_path']))
+        if self.raw is None:
+            log.error('raw not found')
+            return
+        if self.arc is None:
+            log.error('arc not found')
+            return
+        if self.flat is None:
+            log.error('flat not found')
+            return
+        if self.sky is None:
+            log.error('sky not found')
+            return
 
+        hdul_raw = fits.open(os.path.join(self.root_dir, self.raw['file_path']))
         hdul_arc = fits.open(os.path.join(self.root_dir, self.arc['file_path']))
         hdul_flat = fits.open(os.path.join(self.root_dir, self.flat['file_path']))
         hdul_sky  = fits.open(os.path.join(self.root_dir, self.sky['file_path']))
diff --git a/tests/test_common_ephem.py b/tests/test_common_ephem.py
new file mode 100644
index 0000000000000000000000000000000000000000..c6d0295d1995e5b4343a5cc5dda11c7d9bc98d3a
--- /dev/null
+++ b/tests/test_common_ephem.py
@@ -0,0 +1,14 @@
+import os
+import unittest
+from astropy.io import fits
+
+from csst_dfs_api.common.ephem import EphemSearchApi
+
+class CommonEphemTestCase(unittest.TestCase):
+
+    def setUp(self):
+        self.api = EphemSearchApi()
+
+    def test_gaia_query(self):
+        recs = self.api.gaia_query(ra=260, dec=-27, radius=0.01, mag=0.01, limit=2)
+        print('find:', recs)