diff --git a/csst_dfs_commons/utils/fits.py b/csst_dfs_commons/utils/fits.py
index b89ec8f9b46c98a36f85a54a955326d20dac06a3..67cb138ecc8ea0047fd039588c9ef5819cdaa3f0 100644
--- a/csst_dfs_commons/utils/fits.py
+++ b/csst_dfs_commons/utils/fits.py
@@ -112,8 +112,7 @@ def dfs_heapix_sql_condition(ra, dec, radius, ra_col = 'ra', dec_col = 'dec', br
 
     return whereSql
 
-def compute_ra_dec_range(hdulist):
-    header = hdulist[1].header
+def compute_ra_dec_range(header):
     fits_wcs = wcs.WCS(header)
 
     # Get the shape of the data