Arrival time files
The tempo2 arrival time file format (which typically has the file extension .tim) has the following form:
FORMAT 1
directory/filename frequency sat uncertainty site
The FORMAT 1 statement defines this file to be a tempo2 format arrival time file. If a directory and filename is not available then the first column in this file can simply be an identifier for the particular observation. The frequency (in MHz), arrival time (MJD) and uncertainty (µs) can be given to any number of decimal places.
Using flags
Each arrival time line may have one or more “flags” that provide extra information for the user and the tempo2 algorithms. A few pre-defined flags have been set, but the user is free to define as many flags as required.
The flags may be given in any order (and flags do not have to be set for all observations). Flags can be used for numerous purposes including:
Selecting data: command line arguments can be used to filter observations based on their flag values.
For instance:
$ tempo2 -f mypar.par mytim.tim -pass "-b WBCORR DFB4"
will only select observations that have a “-b” flag set to “WBCORR” or to “DFB4”.
$ tempo2 -f mypar.par mytim.tim -filter "-rcvr 10CM"
will reject all observations that have a “-rcvr” flag set to “10CM”. (More complex filters are available using the select plugins or through a “select file”.)
Dealing with phase jumps between instruments/observatories:
It is common to include a phase jump between observations from different instruments or observatories. Sometimes these phase jumps are known and can be fixed. Usually, such jumps are measured as part of the tempo2 fit. The timing model can be updated to include
JUMP -rcvr 10CM 0 1
JUMP -rcvr MULTI 0 1
that will include a fit for the phase jump for data obtained with the 10CM receiver and for a phase jump for the MULTI receiver. These jumps are with respect to any observations that were not obtained using the 10CM and MULTI receivers (note: you cannot place a jump around all
observations - the jumps d to be with respect to a set of arrival times),
Highlighting particular observations:
The plk plugin allows particular observations to be highlighted. This can be initiated from the command line:
$ tempo2 -gr plk -f mypar.par mytim.tim -colour -rcvr
will draw the observations with different “-rcvr” flags with different colours. Within the plugin, the ctr-i and ‘H’ options enable further highlighting of particular observations.
