LO1TBL Column Definitions

DMJD

This item time-stamps the data for the row. Units are days.

RA

This field indicates the telescope pointing direction, in degrees of right ascension, in the co-ordinate system described by header keywords RADESYS and EQUINOX

DEC

This field indicates the telescope pointing direction, in degrees of declination, in the co-ordinate system described by keywords RADESYS and EQUNIOX

LO1FREQ

This column specifies the Doppler shifted frequency. This is the actual commanded frequency sent to the synthesizer.

VFRAME

(Standard keyword from the GBT Engineering FITS Files document, section D.2.) This field describes the radial velocity of the reference frame with respect to the observer, i.e.:

$$VFRAME = V_{frame} - V_{observer}$$ (1)

Note, this is a true (relativistic velocity), independent of the velocity definition and reference frame specified for the source velocity.

RVSYS

(Standard keyword from the GBT Engineering FITS Files document, section D.2.) This field contains the systemic radial velocity of the source with respect to the observer

$$RVSYS = (V_{frame} + V_{relative}) / (1 + V_{frame}*V_{relative}/C^2))$$ (2)

Note, this is a true (relativistic velocity), independent of the velocity definition and reference frame specified for the source velocity.

An example LO1TBL header is given below:

XTENSION= 'BINTABLE'           / binary table extension
BITPIX  =                    8 / 8-bit bytes
NAXIS   =                    2 / 2-dimensional binary table
NAXIS1  =                   48 / width of table in bytes
NAXIS2  =                    1 / number of rows in table
PCOUNT  =                    0 / size of special data area
GCOUNT  =                    1 / one data group (required keyword)
TFIELDS =                    6 / number of fields in each row
TTYPE1  = 'DMJD    '           / label for field   1
TFORM1  = '1D      '           / data format of field: 8-byte DOUBLE
TUNIT1  = 'd       '           / physical unit of field
TTYPE2  = 'RA      '           / label for field   2
TFORM2  = '1D      '           / data format of field: 8-byte DOUBLE
TUNIT2  = 'deg     '           / physical unit of field
TTYPE3  = 'DEC     '           / label for field   3
TFORM3  = '1D      '           / data format of field: 8-byte DOUBLE
TUNIT3  = 'deg     '           / physical unit of field
TTYPE4  = 'LO1FREQ '           / label for field   4
TFORM4  = '1D      '           / data format of field: 8-byte DOUBLE
TUNIT4  = 'Hz      '           / physical unit of field
TTYPE5  = 'VFRAME  '           / label for field   5
TFORM5  = '1D      '           / data format of field: 8-byte DOUBLE
TUNIT5  = 'm/sec   '           / physical unit of field
TTYPE6  = 'RVSYS   '           / label for field   6
TFORM6  = '1D      '           / data format of field: 8-byte DOUBLE
TUNIT6  = 'm/sec   '           / physical unit of field
EXTNAME = 'LO1TBL'             / name of this binary table extension
END