Selection Criteria

Default selection criteria are defined by the SET  command. For most selection criteria, an option to the FIND  command exists, with the same name, which may be used to impose temporary values to the FIND command ; the default values are unchanged by the FIND options.

 
• SET TYPE Name is more than a selection criterium, since it specifies on which type of observations the CLASS program works. Name can be ``Continuum'', ``Line'' or ``Spectroscopy'', or ``Skydip''.

   

• SET LINE Name for the line name to be used. A line name of the form ABC* indicates that all lines beginning by ABC are to be selected. The default is *, i.e. any line name.

   

• SET NUMBER n1 n2 for the range of observation numbers. Default is * *, i.e. any observation number ; * n2 specifies all observation numbers smaller than n2.

   

• SET OBSERVED d1 d2 for the range of observing dates. A date is specified in the format dd-mmm-yyyy, e.g. 19-jan-1985. Default is * *, i.e. any date ; 19-JAN-1985 * means any date later than January 19 , 1985.

   

• SET OFFSET o1 o2 for offsets of the position to be used (in the system and units specified by SET COORDINATE and SET ANGLE). Default is * *.

   

• SET RANGE w e s n is a less restrictive way to specify position offsets. A rectangular area of sky is defined by its west, east, south and north limits (in current angle units).

   

• SET REDUCED d1 d2 for a range in reduction dates ; same specifications and defaults as for SET OBSERVED.

   

• SET SOURCE Name for the source name ; same specifications as SET LINE.

   

• SET SCAN s1 s2 for a range of original scan numbers. Scan numbers should not be confused with Observation numbers (the numbers by which an observation is uniquely identified). They are essentially ``historical'' numbers defined by the acquisition system, but usually with different ``observations'' (in the CLASS meaning) for a single scan. The scan number is kept only for bookkeeping purpose.

   

• SET TELESCOPE Name for the Telescope name. For the IRAM 30-m telescope, the telescope name contains coded into the last 3 letters the backend used for the observations. Similar conventions are used for the POM-2 and IRAM 15-m telescopes.

The tolerance parameter defined by SET MATCH  also influences on the position searches, since this parameter (in the current angle unit) is used to check agreement with the specified limits.   Another option to the FIND command is /ALL which enables one to find all the versions of of observations satisfying the selection criteria (otherwise only the most recent version is selected). Note that the system is intended to work only with the last version of observations, so that the use of the /ALL option should remain exceptional.