Select the event lists, the HK files, the MKF files or the obscat on the basis of any available criteria based on the columns in the FITS file that can be encoded into a Boolean expression.
xsel > select <select_what> <expression> [mkf_name] [mkf_def_expr]
The following guidelines on how to construct the <expression> are taken directly from the help file for the FSELECT FTOOL: This task creates a new table from a subset of rows in an input table. The rows are selected on the basis of a boolean expression whose variables are table column names. The column names are not case sensitive, but the values are. If, after substituting the values associated with a particular row into the column name variables, the expression evaluates to true, that row is included in the output table. Boolean operators can be used in the expression in either their Fortran or C forms. The following boolean operators can be used in the expression:
The expression may also include arithmetic operators and functions. Trigonometric functions use degrees, not radians. The following arithmetic operators and functions can be used in the expression:
In addition several constants are built in for use in expressions:
A string constant must be enclosed in quotes as in ``Crab". Due to the generalities of FITS column names, a column name which resembles an arithmatic or boolean expression should be enclosed in $column-name$ to force its interpretation as a column.