pointingTab.html

Table 1:

POINTING: Antenna pointing information


Name	Format	Units	Measure	Comments

Columns

Key
ANTENNA_ID	Int			Antenna id.
TIME	Double	s	EPOCH	Integration midpoint
INTERVAL	Double	s		Interval midpoint

Data
NAME	String			Pointing position desc.
NUM_POLY	Int			Series order
TIME_ORIGIN	Double	s	EPOCH	Origin for the polynomial
POINTING_DIRECTION	Double(2, NUM_POLY+1)	rad	DIRECTION	Antenna pointing direction
TARGET	Double(2, NUM_POLY+1)	rad	DIRECTION	Target direction
(POINTING_OFFSET)	Double(2, NUM_POLY+1)	rad	DIRECTION	A priori pointing corrections
(SOURCE_OFFSET)	Double(2, NUM_POLY+1)	rad	DIRECTION	Offset from source
(ENCODER)	Double(2)	rad	DIRECTION	Encoder values
( POINTING_MODEL_ID)	Int			Pointing model id.
TRACKING	Bool			True if on-position
(ON_SOURCE)	Bool			True if on-source
(OVER_THE_TOP)	Bool			True if over the top

Notes: This table contains information concerning the primary pointing direction of each antenna as a function of time. Note that the pointing offset for individual feeds on a given antenna are specified in the FEED sub-table with respect to this pointing direction.

ANTENNA_ID: Antenna identifier
TIME: Mid point of the time interval over which the data in the row are valid. Require to use the same TIME Measure reference as in MAIN
INTERVAL: Time interval
NAME: Pointing direction name; user specified
NUM_POLY: Series order for the polynomial expressions in POINTING_DIRECTION¹ and POINTING_OFFSET
TIME_ORIGIN: Time origin of the polynomial expression in DIRECTION and POSITION_OFFSET
POINTING_DIRECTION: Antenna pointing direction, optionnaly expressed as polynomial coefficients. The final result is interpreted as a Direction Measure using the specified Measure refernce. Original name was DIRECTION
TARGET: Traget pointing direction, optionnaly expressed as polynomial coefficients. The final result is interpreted as a Direction Measure using the specified Measure reference. This is the true expected position of the source, including all coordinate corrections such as precession, nutation etc...
POINTING_OFFSET: The a priory pointing corrections applied by the telescope in pointing to the DIRECTION position, optionally expressed as polynomial coefficients. The final result is interpreted as a Direction Measure using the specified Measure reference. These are pointing offsets applied on top of the pointing model. They correct anything not accounted by the model (thermal variations, atmospheric refraction, ...)
SOURCE_OFFSET: The commanded offset from the source position, if offset pointing is being used.
ENCODER: The current encoder values on the primary axes of the mount type for the antenna, expressed as a Direction Measure. Thes are absolute values.
POINTING_MODEL_ID: Pointing model identifier
TRACKING: True if tracking the nominal pointing position
PHASE_TRACKING: True if tracking the nominal phase reference direction
ON_SOURCE: True if the nominal pointing direction coincides with the source, i.e. offset-pointing is not being used.
OVER_THE_TOP: True if the antenna was driven to this position “over the top” (az-el mount).