The Magellan Classic Cam raw FITS data have a sequence number but no UT date in their names. There is a preprocessor C-shell script which must be invoked once, normally before the first ORAC-DR initialisation. If you enter
% cc2oracdrin a directory containing Classic Cam FITS files, the command converts them into NDFs with names adhering to the UKIRT convention. The prefix is cc. The earliest file has observation number 100 (a Classic Cam convention), and the observation number increments for each FITS file in sequence-number order.
It also writes the observation and group numbers, and the number of offsets in the grouped observation into the headers, to assist ORAC-DR.
ORAC-DR -- imaging data reduction