PHASETRACKING: Antenna phase tracking information

PHASE_TRACKING: Antenna phase tracking information

Name

Format

Units

Measure

Comments

Columns

Key

ANTENNA_ID

Int Antenna identifier

FEED_ID

Int Feed identifier

SPECTRAL_WINDOW_ID

Int Spectral window id.

TIME

Double s EPOCH Interval midpoint

INTERVAL

Double s Time interval

Data

DELAYOFF1  

Double s Delay offset of antenna

DELAYOFF2  

Double s Relative delay offsets

PHASEOFF1  

Double rad Phase offset on LO

PHASEOFF2  

Double rad Phase offset on LO2

RATEOFF1  

Double rad s-1 Phase rate offset on LO

RATEOFF2  

Double rad s-1 Phase rate offset on LO2

(PHASE_REF_OFFSET)   

Double rad A priory phase offset applied

Notes: Time variable phase tracking. These data are indexed by the MAIN table columns (TIME, ANTENNAn, FEEDn, SPECTRAL_WINDOW_ID).
ANTENNA_ID
FEED_ID
SPECTRAL_WINDOW_ID
TIME
Mid point of time interval for which the feed parameters in the row are valid. The same reference used fir the TIME column in the MAIN  must be used.
INTERVAL
Time interval.
DELAYOFF1
  Delay offset, Change when antenna is moved. 1.
DELAYOFF2
  Relative delay offsets in basebands; should not change when antenna is moved.
PHASEOFF1
  Phase offsetfootenote on LO1, in addition of normal phase tracking
PHASEOFF2
  Phase offsetfootnote on LO2, in addition of normal phase tracking
RATEOFF1
  Phase rate offsetfootenote on LO1, in addition of geometrical tracking..
RATEOFF2
  Phase rate offset in addition of geometrical tracking. It is physically the same thing as a frequency offset; it adds up to the nominal LO frequencies as specified in the spectral windows for each baseband.
PHASE_REF_OFFSET
A priori phase offset correction applied when using phase referencing (Fast-Switching observing mode) This phase offset is determined from the last observations on a FIELD_IDwhich is an associated FIELD of the current FIELD 

Remarks:
These delay and phase offsets being applied, in hardware, per baseband, SPECTRAL_WINDOW_ID  corresponds to CHANNEL-ZERO associated spectral windows. (Would, between antennas, uncorrelated phase and delay offsets with a spectral dependency be present through the baseband, this information would be stored refering to associated spectral windows with the proper spectral resolution. In that case dimension N_f need to be added.) 
N.B.:
Phase tracking due to the geometry, e.g. in the On-The-Fly with cross-correlation observing mode, is set in the FIELD  table. Other effects for phase-tracking are considered here in this PHASE_TRACKING  table. This includes atmospheric on-line phase referencing (Fast-Switching observing mode).