HEADER contains standard header items describing an observation. These are drawn from the following list as relevant for a particular dataset.
TARGET <_CHAR*40> - name of astronomical source
OBSERVER <_CHAR*40> - name of owner
OBSERVATORY <_CHAR*40> - e.g. 'EXOSAT'
INSTRUMENT <_CHAR*40> - particular instrument (e.g.
'ME')
AXIS_RA <_DOUBLE> - RA in decimal degrees of
pointing axis (or more general
spatial reference point)
AXIS_DEC <_DOUBLE> - declination in decimal degrees
of spatial reference point
EQUINOX <_INTEGER> - equinox (year) for RA and Dec
POSITION_ANGLE <_DOUBLE> - Angle (degrees) from North
through East to +ve y axis
(i.e. standard astronomical PA
of +y axis)
FIELD_RA <_DOUBLE> - RA of field centre
FIELD_DEC <_DOUBLE> - declination of field centre
BASE_DATE <_CHAR*11> - day of observation reference
time: dd-mmm-yyyy (This
contains the same information
as BASE_MJD, and is provided
for user convenience)
BASE_MJD <_INTEGER> - MJD of observation reference
time (whole part only)
BASE_UTC <_DOUBLE> - UTC in seconds of the reference
time, measured from 0:0 on the
day of BASE_DATE/BASE_MJD
BASE_TAI <_DOUBLE> - Atomic time (TAI) since 0:0 UTC
on Jan 1st 1972, in units of
days. This is the standard
continuous reference time
system used by ASTERIX.
OBS_LENGTH <_REAL> - total observing time in
seconds, making no allowance
for dead time losses etc
EXPOSURE_TIME <_REAL> - actual exposure time in seconds
after allowing for any data
losses
The contents of HEADER and of the PROCESSING structure described below can be conveniently inspected using the HEADER application.