National Aeronautics and Space Administration

EARTH2SUN (Jan96)             xanadu.xronos            EARTH2SUN (Jan96)



NAME 
    earth2sun -- corrects times in the column TIME at the barycenter  of
    the solar system.
    
    
USAGE
    earth2sun  input column output ra dec
    
    
DESCRIPTION
    This  task  corrects  the arrival time of photons, assumed as tagged
    at earth, for the time delay EARTH-SUN.  No  other  corrections  are
    applied,  in  particular  it  is  not  included  the corrections for
    travel time from the satellite-earth or any spacecraft clock  delay.
    This program uses the JPL DE200 ephemeris,given as FITS binary table
    (Standish,M.,1982 Astr. Ap.,114,297). The file validity is  till  31
    December 2050. The task takes as input only FITS  file  with  binary
    table extension. The format of the FITS input file can  contain many 
    extensions. The  task  corrects  the  times  only in  one   selected
    extension.The selected extension can be specified at the input level 
    (see parameter input file). If the FITS file is  an  EVENT  list the  
    times  in  the  EVENT  and  GTI extensions are corrected.  A file is
    assumed an EVENT list if  the  EXTNAME  and/or    HDUCLAS1  keywords 
    contain the string EVENT (or EVENTS). The column name containing the 
    time  values  can  be  specified  at  input  level  (see   parameter 
    Column  name). The default column name is TIME. The   time values in
    the TIME column are expected to  be  either  MJD  (or   TJD  or  JD) 
    values  (1) or  residuals  from  a  MJD  reference time (2) given as 
    header  keyword.   In  the  first  case  (the  time  column contains  
    values  written as a MJD or JD or TJD), the header keyword 'TIMESYS' 
    is required, containing with one of the following  values: MJD or JD 
    or  TJD.  In  the second case, the  keyword  'MJDREF' (or 'MJDREFI', 
    integer  part,  and  'MJDREFF'  fractional  part)  should contain an 
    MJD  value.  If  MJDREF is not found and TIMESYS is not  either  MJD 
    or JD or TJD the program gives a fatal error.
    
    A GTI extension is expected in the file  if  the  FITS  file  is  an
    EVENT  list,  and it is identified if the either EXTNAME or HDUCLAS1
    keyword contain the string  GTI  (or  ALLGTI  or  STDGTI).  The  GTI
    extension  format  must  have  at  least two columns named START and
    STOP and no other column named are searched and/or  recognized.  The
    task  adds  and/or  replaces  a number of header keywords. TIMREF is
    set to 'SOLARSYSTEM'.  TSTART and TSTOP are set either to the  first
    and  last  value in the TIME column or if an EVENT list to the first
    start GTI and last stop GTI.
    
    
PARAMETERS
    
    infile [file name + extension]
        The  name  of  the  input  file  for  which  the  correction  is 
        needed.     The  extension can be specified either as "infile+#"
        or "infile[#]"    where # is the extension number.
    
    colnam [time] 
        The name of the column containing the times value. Default  name
        is TIME.
    
    outfile [file name]
        The  name  of  the  output file. Note in the output file all the
        extensions present in the input file are copied.
    
    ra  [RA source]
        The RA of the source (either in  hh:mm:ss.s  or  deg)  given  in
        2000.0 equinox.
    
    dec [DEC source]
        The  DEC  of  the source (either in  dd:mm:ss.s or deg) given in
        2000.0 equinox.
    
    tchat (terminal chattiness) 
        Set terminal chattiness.
    
    lchat (log file chattiness) 
        Set log file and chattiness in the log file:= 0 the log file  is
        not  written.   For all the other value the chattiness is set as
        for the terminal
    
    logname (log filename)
        Name for the log file. The defaults is earth2sun.log
    
    ephfile (ephemeris file)
        Name and path of the ephemeris file.  Ephemeris  valid till   31 
        December 2000
        
        
BUGS
    Report     problems     to     angelini@lheavx.gsfc.nasa.gov     and    
    xanprob@athena.gsfc.nasa.gov.   Provide  a  detailed  description of
    the problem (with a log file if possible).