NAME gtvcut - This tool displays a summary of the Data Sub-Space keywords. USAGE gtvcut infile table DESCRIPTION gtvcut is used to view the Data Sub-Space (DSS) keywords in a given extension, where the EVENTS extension is assumed by default. The DSS keywords scheme was introduced for recording data selection criteria in a systematic manner. Note that inspection of the file extension with the tools fv or ds9 would serve the same purpose. For FERMI data, DSS keywords store information in the FITS headers about the selection criteria that have been applied to the data using the gtselect tool (type "fhelp gtselect" for further explanation). The DSS keywords are used by the exposure-related tools (gtexpmap, gtrspgen) and by gtlike for calculating various quantities, such as the predicted number of detected events given the source model. These keywords must be exactly the same for all of the filtered event files considered in a given analysis. gtlike will check to ensure that all of the DSS keywords are the same in all of the relevant files. A filtering condition is expressed with a set of keywords (e.g., DSTYP1, DSUNI1, DSVAL1, and DSREF1). For example, selecting events in a given time interval (TIME>start_time&&TIMEstart_energy&&ENERGY gtvcut This will prompt for parameter values. Not all parameter are prompted: some of them are "hidden". To change one of the "hidden" parameter, the user should specify the values in the command line or modify its mode by editing the parameter file. For example, to suppress the printing of the individual GTI start and stop times, the following command line as to be typed: > gtvcut suppress_gtis=yes In the next example the gtselect tool (see the gtselect help) was applied first selecting a time range of the events in the original event file between 252374400 (MET sec) and 252460800 (MET sec), an energy range between 30 MeV and 200000 MeV, and a region of 20 degrees from a central point at coordinates RA=193.98 DEC=-5.82. > gtvcut Input FITS file[] events.fits Extension name[EVENTS] The output is as follows: DSTYP1: BIT_MASK(EVENT_CLASS,0,P7REP) DSUNI1: DIMENSIONLESS DSVAL1: 1:1 DSTYP2: POS(RA,DEC) DSUNI2: deg DSVAL2: CIRCLE(193.98,-5.82,20) DSTYP3: TIME DSUNI3: s DSVAL3: TABLE DSREF3: :GTI GTIs: 252374400 252460800 DSTYP4: ENERGY DSUNI4: MeV DSVAL4: 30:200000 DSTYP5: ZENITH_ANGLE DSUNI5: deg DSVAL5: 0:105 That last example could be also be run in the command line as follows: > gtvcut infile=events.fits table=EVENTS KNOWN BUGS SEE ALSO gtselect