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Space Telescope Imaging Spectrograph
Errors in Processed TIME-TAG Data from STIS Now Corrected

As discussed in the March 2001 STAN, various errors may exist in TIME-TAG datasets. New archive software installed on 2001-Sep-13 repairs all known problems in TIME-TAG datasets. Every dataset retrieved after 2001-Sep-13 should be free of TIME-TAG errors.

STIS MAMA detector electronics occasionally report an erroneous time. The previous ground processing software failed to properly trap these errors. As a result, gaps or jumps in time could occur in processed TIME-TAG data. Also, the existing ground software did not properly flux calibrate data from observations in which the actual exposure time differed from the EXPTIME keyword value (i.e. the requested exposure time). This can happen when STIS memory fills before it can be dumped, for example. None of these issues affected STIS MAMA data obtained in ACCUM mode. All investigators working with STIS TIME-TAG data should read the more detailed discussion of possible problems, and if they believe that their data may have been affected, retrieve it again from the archive.