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Observational data

Every instrument seems to produce its data in a different format. However, it is relatively simple to re-format the data to a standard form; MIDAS table files are the obvious standard form to use. Usually the conversion is done in two steps: first reformat the existing data as an ASCII file with all records in the same format, and then convert this ASCII file to MIDAS table format.

The ASCII re-formatting can be done by a user-written program, or by using UNIX tools such as the stream editor (sed) and the table-oriented programming language awk. While the UNIX manual pages provide little useful information on these tools, there are some excellent books available, such as [4] and [1].

Often, much of the work has already been done. If a program exists that reads the current instrumental data, it can readily be modified to read the data and then reproduce them as an ASCII file, suitable for conversion to MIDAS table format. The data-reading part of the existing program is adaptable as the front end of the reformatter. To simplify the conversion, FORTRAN routines will be made available to handle the back end. Thus, very little work really has to be done. In any case, the reformatting program only has to be written once for a given instrument.

ESO telescopes provide relatively clean data files, but these files contain more than one kind of record. Thus, even these data files must be reformatted before they can be converted to MIDAS tables by the CREATE/TABLE command. Programs will be provided to convert data from ESO telescopes to the standard table format.



 
next up previous contents
Next: Required observational data Up: File Formats Required for Previous: CCD photometry
Petra Nass
1999-06-15