BARYTIME (Mar02)               ftools.gro               BARYTIME (Mar02)



NAME 
    barytime --     
    
USAGE 
    barytime  miscdir  outputdir  inputfile  outputfile  printfile coord
    rastring  decstring angsel consiz mincon  angmin  angmax  emin  emax
    zensel zenmax zenoff clobber     
    
DESCRIPTION  
    This  routine  reads  EGRET event files, performs user-selected cuts
    on photon direction, energy and quality  screening  parameters,  and
    produces  an  output  list with a column containing the solar-system
    barycenter corrected photon arrival times. The output file can  then
    be  used  as input to other LHEAsoft temporal anlaysis tools such as
    "efold", "lcurve" or "powspec" to perform detailed temoral  analysis
    (it  also  retains  the  same  basic structure as the original event
    file, and can be used with other EGRET software). Specifically,  the
    corrected  photon  arrival  times in units of Julian Days are listed
    in the table column labled "TIME",  in  the  first  table  extension
    (called EGRET_SMDB) of the output file.     
    Note  that  the direction specification should be that of the source
    in  question,  not  that  the  observatory  Z-axis.   For   a   wide 
    field-of-view  instrument  such  as  EGRET  the  difference  becomes 
    signifcant. This is the reason there is  not  simply  a  bary-center
    corrected time column in the archive files.      
    The  input event files are in FITS table format, and follow a naming
    convention:  "qvp3040f.fits.gz"  where  the  3040   indicates   CGRO 
    Viewing  Period  304.0. These data are available through the HEASARC
    Browse  system  or   by   direct   WWW   or   FTP   download,   e.g. 
    <ftp://cossc.gsfc.nasa.gov/compton/data/egret/high_level/phase3/pnt_3040>
    in  the  case  of  the  aforementioned  example  (the CGRO observing
    schedules or "Timelines" for the 9 year mission  are  available  at:
    <http://cossc.gsfc.nasa.gov/timeline/index.html>).     
    This  utility  is derived from the program "PULSAR" developed by the
    EGRET instrument team.     
    
    
PARAMETERS 
    
    miscdir[string]         
        name of directory containing pulsar and timeline files     
    outputdir [string]         
        name of directory for output files     
    inputfile [string]         
        name of the input file     
    outputfile [string]         
        name of the output file     
    printfile [string]         
        name of the output files to write ascii/debug information to     
    coord [string]         
        coordinate system (celestial/galactic)     
    rastring [string]         
        source right ascension (note: this field is  galactic  longitude
        galactic coordinates are selected)     
    decstring [string]         
        source  declination  (note:  this  field  is  galactic longitude
        galactic coordinates are selected)     
    angsel [string]         
        angular selection (should fixed or  energy-dependent  acceptance
        cone  about  the  source  location be used; generally "fixed" is
        recommended)     
    consiz [real]         
        acceptance cone. For energy-dependent  angular  selection,  this
        is  approximately  the angle theta=5.85x(E/100MeV)^(-.53), which
        contains about 68-percent of the source photons     
    mincon [real]         
    
    angmin [real]         
        minimum  cone  size  (deg).  For  a  energy  indpendent  angular 
        selection,  this  is  the  mainimum allowable incident gamma-ray
        aspect angle relative to the source (generally 0)     
    angmax [real]         
        maximum  cone  size  (deg).  For  a  energy  indpendent  angular 
        selection,  this  is  the  maximum  allowable incident gamma-ray
        aspect angle relative to the source.     
    emin [real]         
        minimum gamma-ray energy to include (MeV)     
    emax [real]         
        maximum gamma-ray energy to include (MeV)     
    zensel [string]         
        zenith angle selection (fixed/energy dependent)     
    zenmax [real]         
        maximum zenith angle (deg)     
    zenoff [real]         
        offset from earth limb     
    clobber [int]         
        indicates whether or not to overwrite existing output files         
        
        
EXAMPLES 
    
    1.  Generate a SSBC corrected photon arrival time list for the  Crab
    pulsar,  using  data  obtained  during CGRO Viewing Period 1. Photon
    energies between 100 and 1000 MeV are to be included.     
    barytime   inputfil=qvp0010f.fits   emin=100    emax=1000    coord=g  
    rastring=184.56 decstring=-5.78  angsel=fixed angmin=0.0 angmax=5.0     
    
    
BUGS 
    
    
SEE ALSO