DATA Binary Table Extension

The DATA table contains a (large) DATA column containing counts from both banks of the Spectral Processor.

An example extension header, and a subset of the data is given below:

DATA Binary Tables Extension: Header
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XTENSION= 'BINTABLE'           / FITS binary table.
BITPIX  =                    8 / Binary data.
NAXIS   =                    2 / Table is a Matrix.
NAXIS1  =                32792 / Width of table in bytes.
NAXIS2  =                    1 / Number of entries (rows) in Table.
PCOUNT  =                    0 / Pointer Count
GCOUNT  =                    1 / Only one group.
TFIELDS =                    7 / Number of fields in each row.
TTYPE1  = 'DMJD    '           /
TFORM1  = '1D      '           /
TUNIT1  = 's       '           /
TTYPE2  = 'UTDTSTRT'           /
TUNIT2  = 'MJD     '           /
TFORM2  = '1J      '           /
TTYPE3  = 'UTCSTRT '           /
TUNIT3  = 'SECONDS '           /
TFORM3  = '1D      '           /
TTYPE4  = 'PSRPER  '           /
TUNIT4  = 'PULSAR PERIOD'      /
TFORM4  = '1D      '           /
TTYPE5  = 'FFTS    '           /
TUNIT5  = 'none    '           /
TDIM5   = '(1,4,2) '           / Structure of 3D item (1, STATE, PORT)
TFORM5  = '8J      '           /
TTYPE6  = 'DELETED '           /
TUNIT6  = 'none'               /
TFORM6  = '8J      '           /
TDIM6   = '(1,4,2) '           / Structure of 3D item (1, STATE, PORT)
TTYPE7  = 'DATA    '           /
TUNIT7  = 'COUNTS  '           /
TFORM7  = '8192E   '           /
TDIM7   = '(1024,4,2)   '      / Structure of 3D item (FREQUENCY, STATE, PORT)
CTYPE1  = 'FREQUENCY'          / First data axis is Frequency
CTYPE2  = 'STATE   '           / Second data axis is State
CTYPE3  = 'PORT'               / Third data axis is Port
EXTNAME = 'DATA              ' / extension name
END

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The DATA table contains rows describing each integration obtained during the scan.

The DMJD column specifies the center of the integration, as does UTDSTRT and UTCSTRT (but more accurately to nail down pulsar work). The PSRPER gives the actual integration time which can vary from integration to integration in pulsar mode. The FFTS and DELETED columns contain the number of Fourier transforms used and the number deleted as the result of RFI excision. They are three-dimensional entries with variable size axes between scans, but constant within a scan, i.e., STATE*PORT. The structure of these 3 dimensional elements are specified by the keywords TDIM5 and TDIM6. The first dimension always has only one element. The structure of the 3 dimensional element DATA is specified by the keyword TDIM7. Its dimensions are defined by the keywords:

CTYPE1

Type of data along the first axis of the DATA's 3 dimensional table element. Normally this FITS keyword entry has the form CTYPE1 = 'FREQUENCY'.

CYTPE2

Type of data along the second axis of the 3 dimensional table element. Normally this FITS keyword entry has the form CTYPE2 = 'STATE'.

CYTPE3

Type of data along the third axis of the 3 dimensional table element. Normally this FITS keyword entry has the form CTYPE3 = 'PORT'.