NAME gtbary - Performs barycentric or geocentric corrections to photon arrival times. USAGE gtbary evfile scfile outfile ra dec DESCRIPTION This tool performs barycentric or geocentric corrections to photon arrival times in input event file(s) using a Fermi orbit file. The heart of this executable is taken from axBary by Arnold Rots at SAO. Minimal modifications were made to axBary to work with Fermi orbit files. This is also equivalent to the barycorr tool in HEADAS. Upon startup, the user will be prompted for the input file whose times will be corrected, the orbit file to use for the correction, the output file (which may be the same as the input file) and the Right Ascension (RA) and Declination (Dec) of the source (pulsar) location from which to correct the photon arrival times. Three additional ancillary files are needed by gtbary/axBary in order to perform the correction: JPLEPH.405, leapsec.fits and tai-utc.dat. The program looks for these files in the directory given by the TIMING_DIR environment variable. For the moment, these files are included in the data subdirectory of the timeSystem package. In the event that an error occurs during the correction, the input file will be left in its original state, even if the correction is being performed in place. When debugging is enabled (by typing debug=yes on the command line), a temporary file containing the state of the correction when the error occurred will be left for investigative purposes. The temporary file name is identical to the output file name with an added suffix of .tmp. PARAMETERS evfile [file name] Name of input event file scfile [file name] Name of input spacecraft data file outfile [file name] Name of output file. If the same as evfile, the arrival time correction will be performed in situ in the input file (which must therefore be writable). ra [double] Right Ascension of point source in degrees for which to perform the arrival time correction. dec [double] Declination of point source in degrees for which to perform the arrival time correction. (tcorrect = BARY) [enumerated string (GEO|BARY)] Arrival time correction to apply. Choose BARY to apply the barycentric correction, and GEO the geocentric correction. (solareph = JPL DE405) [enumerated string (JPL DE200|JPL DE405)] Solar system ephemeris for the barycentric correction. (angtol = 1.e-8) [double] Angular tolerance in degrees in comparison of two source positions, one for which the barycentric correction is performed, and another given by RA_NOM and DEC_NOM header keyword of an event file to which the barycentric correction has already been applied. This parameter only has effect if the barycentric correction has been applied to an input event data file. If the two source positions are separate from each other by this amount or less, then they will be considered to be the same position. Otherwise an error will be generated. The sign of the parameter value is ignored. For example, setting angtol=-1.0 results in giving angular tolerance of 1 degree. (timefield = TIME) [string] Name of the field containing the time values for temporal analysis. (sctable = SC_DATA) [string] Name of the FITS table containing the spacecraft data. (leapsecfile = DEFAULT) [file name] Name of the file containing the name of the leap second table, in OGIP-compliant leap second table format. If leapsecfile is the string DEFAULT, the default leap-second file (leapsec.fits), which is distributed with the extFiles package, will be used. (chatter = 2) [integer, min=0, max=4] This parameter fixes the output verbosity: no screen output (0), nominal screen output (2), maximum verbosity (4). (clobber = yes) [boolean] Overwrite or do not overwrite existing output files. (debug = no) [boolean] Activate debugging mode. When debug is "no", all exceptions that are not caught and handled by individual tool-specific code are caught by a top-level exception handler that displays information about the exception and then exits. When debug is "yes", such exceptions are not caught by the top level code. Instead the tool produces a segmentation violation, which is more useful for debugging. When debugging mode is enabled, the tool produces more verbose output describing any errors or exceptions that are encountered. (gui = no) [boolean] Graphical user Interface (GUI) mode activated if "yes" is specified. (mode = ql) [string] Mode of automatic parameters. EXAMPLES In the following example, gtbary processes the event file fakepulsar_event.fits using the spacecraft data file named simscdata_1week.fits for a pulsar located at the right ascension of 111.11 and the declination of 22.22. > gtbary evfile=fakepulsar_event.fits scfile=simscdata_1week.fits \ outfile=fakepulsar_event_bary.fits ra=111.11 dec=22.22 When successful, gtbary creates an output file (fakepulsar_event_bary.fits in the above example) that is ready to be given to a non-Fermi temporal analysis tool that is designed to analyze an event list in the HEASARC standard temporal file format. SEE ALSO barycorr, faxbary, timeconv, barytime, rosbary, aebarycen, earth2sun, fxbary