When Data ONTAP creates a Snapshot copy, the access time of each file in the Snapshot copy is updated to the Snapshot copy creation time.
ls -lu myfile.txt .snapshot/*/myfile.txt-rw-r--r-- 1 smith 0 Jan 14 09:40 myfile.txt
-rw-r--r-- 1 smith 0 Jan 14 00:00 .snapshot/nightly.0/myfile.txt
-rw-r--r-- 1 smith 0 Jan 13 00:00 .snapshot/nightly.1/myfile.txt