ska_oso_pdm._shared.target

The ska_oso_pdm._shared.target module models entities concerned with receptor pointing and mapping (source coordinates, survey fields, pointing patterns, etc.). The contents of the module are presented in the diagram below.

Class diagram for the target module

An example serialisation of this model to JSON is shown below. This describes two target objects: one, a five-point observation centred on Polaris Australis using 5 arcsec offsets between individual pointings, and two, a single pointing observation centred on M83. In both cases, the coordinates are defined using equatorial coordinates using an ICRS reference frame.

  "targets": [
    {
      "target_id": "Polaris Australis",
      "pointing_pattern": {
        "active": "FivePointParameters",
        "parameters": [
          {
            "kind": "FivePointParameters",
            "offset_arcsec": 5.0
          },
          {
            "kind": "RasterParameters",
            "row_length_arcsec": 1.23,
            "row_offset_arcsec": 4.56,
            "n_rows": 2,
            "pa": 7.89,
            "unidirectional": true
          },
          {
            "kind": "StarRasterParameters",
            "row_length_arcsec": 1.23,
            "n_rows": 2,
            "row_offset_angle": 4.56,
            "unidirectional": true
          }
        ]
      },
      "reference_coordinate": {
        "kind": "equatorial",
        "ra": "21:08:47.92",
        "dec": "-88:57:22.9",
        "reference_frame": "icrs",
        "unit": [
          "hourangle",
          "deg"
        ]
      }
    },
    {
      "target_id": "M83",
      "pointing_pattern": {
        "active": "SinglePointParameters",
        "parameters": [
          {
            "kind": "SinglePointParameters",
            "offset_x_arcsec": 0.0,
            "offset_y_arcsec": 0.0
          }
        ]
      },
      "reference_coordinate": {
        "kind": "equatorial",
        "ra": "13:37:00.919",
        "dec": "-29:51:56.74",
        "reference_frame": "icrs",
        "unit": [
          "hourangle",
          "deg"
        ]
      }
    }
  ],

Another JSON example defining two drift scan targets with position specified as azimuth and elevation is shown below.

  "targets": [
    {
      "target_id": "target #1",
      "pointing_pattern": {
        "active": "SinglePointParameters",
        "parameters": [
          {
            "kind": "SinglePointParameters",
            "offset_x_arcsec": 0.0,
            "offset_y_arcsec": 0.0
          }
        ]
      },
      "reference_coordinate": {
        "kind": "horizontal",
        "az": 180.0,
        "el": 45.0,
        "reference_frame": "altaz",
        "unit": ["deg", "deg"]
      }
    },
    {
      "target_id": "target #2",
      "pointing_pattern": {
        "active": "SinglePointParameters",
        "parameters": [
          {
            "kind": "SinglePointParameters",
            "offset_x_arcsec": 0.0,
            "offset_y_arcsec": 0.0
          }
        ]
      },
      "reference_coordinate": {
        "kind": "horizontal",
        "az": 180.0,
        "el": 85.0,
        "reference_frame": "altaz",
        "unit": ["deg", "deg"]
      }
    }
  ],

The ska_oso_pdm._shared.target module defines a Python representation of the target of the observation.

class CoordinateKind(value)

An enumeration.

class Coordinates(*, kind: Literal)

Coordinates is an abstract base class for pointing coordinates.

class CrossScanParameters(*, kind: Literal[PointingKind.CROSS_SCAN] = PointingKind.CROSS_SCAN, offset_arcsec: float = 0.0)

CrossScanParameters defines the properties of an observing pattern that uses a cross scan observing pattern, typically used for pointing calibrations.

class EquatorialCoordinates(*, kind: Literal[CoordinateKind.EQUATORIAL] = CoordinateKind.EQUATORIAL, ra: float | str | None = 0.0, dec: float | str | None = 0.0, reference_frame: EquatorialCoordinatesReferenceFrame | None = EquatorialCoordinatesReferenceFrame.ICRS, unit: str | List[str] | Tuple[str] = ('hourangle', 'deg'))

SiderealTarget represents the argument for SKA scheduling block.

class EquatorialCoordinatesReferenceFrame(value)

Enumeration of reference frames supported by an EquatorialCoordinates

class FivePointParameters(*, kind: Literal[PointingKind.FIVE_POINT] = PointingKind.FIVE_POINT, offset_arcsec: float = 0.0)

FivePointParameters defines the properties of an observing pattern that uses a five-point observing pattern centred on a reference position.

class HorizontalCoordinates(*, kind: Literal[CoordinateKind.HORIZONTAL] = CoordinateKind.HORIZONTAL, az: float, el: float, unit: str | List[str] | Tuple[str] = ('deg', 'deg'), reference_frame: HorizontalCoordinatesReferenceFrame | None = HorizontalCoordinatesReferenceFrame.ALTAZ)

DriftScanTarget defines AltAz target for SKA scheduling block.

class HorizontalCoordinatesReferenceFrame(value)

Enumeration of reference frames supported by a HorizontalCoordinates.

class PointingKind(value)

An enumeration.

class PointingPattern(*, active: PointingKind = PointingKind.SINGLE_POINT, parameters: list[FivePointParameters | CrossScanParameters | SinglePointParameters | RasterParameters | StarRasterParameters] = None)

PointingPattern holds the user-configured pointing patterns and current active pattern for receptor pointing patterns associated with a target.

One of each pointing pattern type can be held in the parameters list. Only the active pattern will be used for observing; the remainder provide an easy way to recover previously edited observing parameters for the target.

class PointingPatternParameters

PointingPatternParameters is an abstract base class extended by classes that define receptor pointing patterns.

abstract class property kind: str

Discriminator field used to distinguish the subclass type of instances that extend PointingPatternParameters. This field is a requirement of the JSON representation, so that the correct class can be instantiated as the JSON is unmarshalled.

kind is an abstract class property and must be defined in any subclass.

class RasterParameters(*, kind: Literal[PointingKind.RASTER] = PointingKind.RASTER, row_length_arcsec: float = 0.0, row_offset_arcsec: float = 0.0, n_rows: int = 1, pa: float = 0.0, unidirectional: bool = False)

RasterParameters defines the properties of an observing pattern that uses a raster pattern centred on a reference position.

class SinglePointParameters(*, kind: Literal[PointingKind.SINGLE_POINT] = PointingKind.SINGLE_POINT, offset_x_arcsec: float = 0.0, offset_y_arcsec: float = 0.0)

SinglePointParameters defines the properties for an observing pattern consisting of a single receptor pointing with an optional offset from the reference position.

class SolarSystemObject(*, kind: Literal[CoordinateKind.SSO] = CoordinateKind.SSO, name: SolarSystemObjectName)

Planet represents the argument for SKA scheduling block.

class SolarSystemObjectName(value)

SolarSystemObjectName represents name of the solar system object.

class StarRasterParameters(*, kind: Literal[PointingKind.STAR_RASTER] = PointingKind.STAR_RASTER, row_length_arcsec: float = 0.0, n_rows: int = 1, row_offset_angle: float = 0.0, unidirectional: bool = False)

StarRasterParameters defines the properties of an observing pattern that uses a star raster pattern centred on a reference position.

class Target(*, target_id: str = '', pointing_pattern: PointingPattern = None, reference_coordinate: EquatorialCoordinates | SolarSystemObject | HorizontalCoordinates = None)

Target represents the receptor pointing for an SKA observation, consisting of a reference position and a pointing pattern to be used when observing the target.

Default pointing patterns and equatorial coordinates will be set if not provided.