This section is taken verbatim from AIPS++ Note 236
These must be provided in all SDFITS tables. They are essential and common to all observations and telescopes. All single dish FITS readers and writers must acknowledge (write and properly interpret) all CORE keywords.
OBJECT
A string value giving an object name.
TELESCOP
A string value giving the telescope name.
BANDWID
The total bandwidth of the backend in units of Hertz.
DATE-OBS
A string giving the observation date and optionally the time at the
start using the new FITS y2k convention. The TIMESYS keyword may be
used to indicate the time system. UTC is assumed if TIMESYS is absent.
EXPOSURE
The effective integration time in seconds.
TSYS
The system temperature in Kelvin.
These have agreeded definitions and interpretations however their presense is optional. These are largely common to all observations and telescopes but not essential. These may be ignored by a single dish FITS reader.
OBSERVER
A string giving the observer's name.
OBSID
A string describing the observation.
PROJID
A string describing the project.
SCAN
A scan ID number. Typically this is an identification number given to a
chunk of data when the data is taken. Not all telescopes provide a scan
ID number.
OBSMODE
The type of data and observing mode (8 characters total). The type
(LINE, CONT, PULS, etc) + the mode (PSSW, FQSW, BMSQ, PLSQ, LDSW, TLPW,
etc). These rules do NOT define these observing modes. Writers are
strongly encouraged to use the FITS comments to document these modes.
MOLECULE
A string used as a line identifier (with TRANSITI).
TRANSITI
A string used as a line identifier (with MOLECULE.)
TEMPSCAL
A string describing the scaling applied to reach the output intensity
scale (``TB'',``TA'',``TA*'',``TR'',``TR*'').
FRONTEND
A string giving the name of the front end device.
BACKEND
A string giving the name of the back end device.
TCAL
The calibration temp (K).
THOT
The hot load temp (K).
TCOLD
The cold load temp (K).
TRX
The receiver temp (K).
FREQRES
The frequency resolution in Hz. This may differ from the channel
spacing.
TIMESYS
The time system which applies to all time columns and keywords (see the
y2k FITS DATE agreement).
VELDEF
The velocity definition and frame (8 characters). The first 4
characters describe the velicity definition. Possible definitions
include:
RADI
radio
OPTI
optical
RELA
relativistic
The second 4 characters describe the reference frame (e.g. ``-LSR'',
``-HEL'', ``-OBS''). If the frequency-like axis gives a frame, then the
frame in VELDEF only applies to any velocities given as columns or
keywords (virtual columns).
VFRAME
The radial velocity of the reference frame wrt the observer. Vframe -
Vtelescope.
RVSYS
The radial velocity, Vsource - Vtelescope.
OBSFREQ
The observed frequency (Hz) at the reference pixel of the
frequency-like axis.
IMAGFREQ
The image sideband freq (Hz) corresp. to OBSFREQ.
LST
The LST (seconds) at the start of scan.
AZIMUTH
The azimuth at TIME (deg) (if the TIME axis is non-degenerate, then
this is the azimuth at the TIME of the first pixel on the TIME axis.
ELEVATIO
The elevation at TIME (deg) (same caveat as for AZIMUTH)
TAU
The opacity at OBSFREQ.
TAUIMAGE
The opacity at IMAGFREQ.
TAUZENIT
The opacity per unit air mass.
HUMIDITY
The relative humidity (fraction, 0..1).
TAMBIENT
The ambient temp (K).
PRESSURE
The atmospheric pressure (mm Hg).
DEWPOINT
The dew point (K).
WINDSPEE
The wind speed (m/s).
WINDDIRE
The wind direction (deg. west of north).
BEAMEFF
The main-beam efficiency.
APEREFF
The antenna aperture efficiency.
ETAL
The rear spillover and scattering efficiency.
ETAFSS
The forward spillover and scattering efficiency.
ANTGAIN
K per Jy.
BMAJ
The major main-beam FWHM (deg).
BMIN
The minor main-beam FWHM (deg).
BPA
The beam position angle (degrees east of north).
SITELONG
The site longitude (deg).
SITELAT
The site latitude (deg).
SITEELEV
The site elevation (m).
RESTFREQ
The rest frequency (Hz).