The FUSE Archival Data Handbook - MAST - STScI

4.1.2 File Name Conventions and Useful Program IDs
All FUSE file names are composed of several identifying elements, but not all files contain each
one of these elements. However, all exposure-level file names have the form {pppp}{tt}{oo}{eee}
and begin with the following four elements:
1. A four-digit program ID searchable in MAST (pppp: a letter plus a three-digit number;
see Tables 4.2, 4.3 & 4.4).
2. A target number (1–99), which identifies the target within the program (tt).
3. An observation number (1–99) which specifies an observing sequence on the target (oo).
Note that a target might have multiple observation numbers if multiple visits at different
times and under different observing conditions were required.
4. An exposure number (1–999) within the given observation (eee).
An example of an exposure-level file name is D0640301004. Note that observation-level files
have eee = 000.
FUSE program ID codes convey general information about the category of the program, be
it primarily for science or calibration. As indicated in Tables 4.2, 4.3 and 4.4, the dividing line
is not hard. Sometimes useful science data can be extracted from data that were obtained for
calibration purposes (for example, the flux calibration programs). Other times, the requirements
of the calibration activity itself may seriously compromise the use of any spectral data for
science. For some ‘I’ programs (in-orbit checkout), the data may be useful for science but only
with great caution since the instrument may not have reached its final science configuration
and focus yet. Many targets observed during in-orbit checkout were re-observed later in the
mission, and the user should be wary of the IOC observation. However, these data are archived
at MAST, so the user should be cognizant. Information on the sequence of instrument focus
activities during in-orbit checkout can be found in the Instrument Handbook (2009); this may
assist the user in evaluating the utility of the IOC observations.
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