TOA LINES

TOAs are entered, one per line, in one of three formats, called
'Princeton', 'Parkes', and 'Interchange TOA (ITOA)' format.  TOAs in
Princeton and Parkes formats are assumed to be referenced in an
observatory time scale (see TIME SCALES, below).  TOAs in ITOA format
are assumed to be referenced to UTC.  TOAs are reported as MJD, except
that TOAs reported using the Princeton format may also be MJD-39126
(also called '1966 day number').  Use of the latter is discouraged.

One-character observatory codes correspond to lines in the observatory
coordinate file for '1' through '9' and 'a' through 'z'.  Code '0' indicates
the geocenter.  Code '@' indicates the solar system barycenter (for which
neither geometric nor clock corrections are applied).  The two-character
observatory codes used in the ITOA format are given in the observatory
coordinate file.

Princeton Format

  columns     item
    1-1     Observatory (one-character code)
    2-2     must be blank
    16-24   Observing frequency (MHz)
    25-44   TOA (decimal point must be in column 30 or column 31)
    45-53   TOA uncertainty 
    69-78   DM correction (pc cm^-3)

Parkes Format

  columns     item
    1-1     must be blank
    26-34   Observing frequency (MHz)
    35-55   TOA (decimal point must be in column 42)
    56-63   Phase offset (fraction of P0, added to TOA)
    64-71   TOA uncertainty
    80-80   Observatory (one-character code)

ITOA Format

  columns     item
    1-2     ignored, but must not be blank (often PSRNAME goes here)
   10-28    TOA (decimal point must be in column 15)
   29-34    TOA uncertainty 
   35-45    Observing frequency (MHz)
   46-55    DM correction (pc cm^-3)
   58-59    Observatory (two-letter code)