nenupy.astro.pointing.Pointing

class nenupy.astro.pointing.Pointing(coordinates, time, duration=None, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)[source]

Bases: AstroObject

Class to handle instrument pointing.

Parameters:

coordinates (SkyCoord) – Pointing coordinates (in the equatorial frame).
time (Time) – Pointing times.
duration (TimeDelta) – Pointing duration.
observer (EarthLocation) – Earth location from where the pointing is made.

See also

Instrument Pointing for more details on how to instantiate and use this class.

Added in version 2.0.0.

Attributes Summary

`time`	Pointing start times.
`duration`	Pointing durations.
`horizontal_coordinates`	Horizontal coordinates as seen from `observer` at `time`.

Methods Summary

`plot`(**kwargs)	Plots the elevation and azimuth versus time for the current pointing.
`from_file`(file_name[, beam_index, ...])	Instantiates a `Pointing` object from a NenuFAR pointing file.
`from_bst`(bst[, beam, analog, max_points])	Instantiates a class:`Pointing` object from a `BST` object.
`target_tracking`(target, time[, duration, ...])	Instantiates a `Pointing` object that tracks a given celestial source target.
`target_transit`(target, t_min[, duration, ...])	Instantiates a `Pointing` object around a source transit.
`zenith_tracking`(time[, duration, observer])	Instantiates a `Pointing` object at the local zenith.

Attributes and Methods Documentation

__init__(coordinates, time, duration=None, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)[source]

Methods

`__init__`(coordinates, time[, duration, observer])
`azel_driftscan`(time, az, alt[, duration, ...])	Return an instance of `Pointing` in drift scan mode.
`from_bst`(bst[, beam, analog, max_points])	Instantiates a class:`Pointing` object from a `BST` object.
`from_file`(file_name[, beam_index, ...])	Instantiates a `Pointing` object from a NenuFAR pointing file.
`hour_angle`([fast_compute])
`local_sidereal_time`([fast_compute])
`plot`(**kwargs)	Plots the elevation and azimuth versus time for the current pointing.
`target_tracking`(target, time[, duration, ...])	Instantiates a `Pointing` object that tracks a given celestial source target.
`target_transit`(target, t_min[, duration, ...])	Instantiates a `Pointing` object around a source transit.
`zenith_tracking`(time[, duration, observer])	Instantiates a `Pointing` object at the local zenith.

Attributes

`custom_ho_coordinates`	Allows to modify horizontal coordinates without messing up with the actual coordinates object.
`duration`	Pointing durations.
`frequency`	test de doc
`ground_projection`
`horizontal_coordinates`	Horizontal coordinates as seen from `observer` at `time`.
`time`	Pointing start times.
`coordinates`
`polarization`
`value`
`observer`

classmethod azel_driftscan(time, az, alt, duration=None, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)[source]

Return an instance of Pointing in drift scan mode. Azimuth az and elevation alt are fixed at every time step.

Parameters:

time (Time) – Time steps of the pointing.
az (float) – Pointed azimuth in degrees.
alt (float) – Pointed elevation in degrees.
duration (TimeDelta, optional) – Duration of the pointings (if a scalar is given it is applied to all time steps), by default None (the duration is set to the difference between each time steps, the last one set at 0).
observer (EarthLocation, optional) – Earth location from where the target is observed, by default nenufar_position.

Returns:

The drift scan pointing instance.

Return type:

Pointing

property custom_ho_coordinates: Allows to modify horizontal coordinates without messing up with the actual coordinates object.

property duration

Pointing durations. If this attribute is scalar, it means that the same duration should be applied to all the start times defined in time.

Setter:: Pointing durations.
Getter:: Pointing durations.
Type:: TimeDelta

property frequency: test de doc

classmethod from_bst(bst, beam=0, analog=True, max_points=100)[source]

Instantiates a class:Pointing object from a BST object.

Parameters:

bst
beam (int)
analog (bool)
max_points

Returns:

Pointing derived from a NenuFAR BST file.

Return type:

Pointing

classmethod from_file(file_name, beam_index=0, include_corrections=True)[source]

Instantiates a Pointing object from a NenuFAR pointing file. Several beam pointings (analog and/or numerical) could be described in file_name. The argument beam_index allows for the selection of one of them.

Parameters:

file_name (str) – NenuFAR pointing file, either analog (ending with .altazA) or numerical (ending with .altazB).
beam_index (int) – Beam number to take into account.
include_corrections (bool) – Include or not the pointing corrections (default is True). Only has an effect on analog beam corrections.

Returns:

Pointing derived from a NenuFAR pointing file.

Return type:

Pointing

Example:

>>> from nenupy.astro.pointing import Pointing
>>> pointing = Pointing.from_file(
        file_name=".../20211104_170000_20211104_200000_JUPITER_TRACKING.altazA",
        beam_index=1
    )

property horizontal_coordinates

Horizontal coordinates as seen from observer at time.

Getter:: Horizontal coordinates.
Type:: SkyCoord

plot(**kwargs)[source]

Plots the elevation and azimuth versus time for the current pointing.

Parameters:

figsize (tuple) – Size of the figure. Default is (10, 5).
figname (str) – File name of the figure to save. Default is '', i.e. show the figure without saving it.
title (str) – Set the title of the figure.
display_duration (bool) – Switch the display of duration. If set to True a grey time window is added to all pointing point, representing the duration of each individual pointing. Default is False.

classmethod target_tracking(target, time, duration=None, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)[source]

Instantiates a Pointing object that tracks a given celestial source target.

Parameters:

target (Target) – Celestial source target to track.
time (Time) – Start times of the pointing aiming at target.
duration (TimeDelta) – Duration of each individual pointing. If this argument is a scalar, then it will be applied to every start time (defined in time). If set to None, the duration is set to the difference between two time steps, the last being set at 0. Default is None.
observer (EarthLocation) – Earth location from where the target is observed. Default is NenuFAR’s location.

Returns:

Pointing derived while tracking a specific target.

Return type:

Pointing

Example:

>>> from nenupy.astro.pointing import Pointing
>>> from nenupy.astro.target import FixedTarget
>>> from astropy.time import Time, TimeDelta
>>> import numpy as np
>>> cyg_a = FixedTarget.from_name("Cyg A")
>>> pointing = Pointing.target_tracking(
        target=cyg_a,
        time=Time("2021-01-01 00:00:00") + np.arange(10)*TimeDelta(1800, format="sec"),
        duration=TimeDelta(np.ones(10)*1200, format="sec")
    )

classmethod target_transit(target, t_min, duration=<TimeDelta object: scale='None' format='sec' value=3600.0>, dt=<TimeDelta object: scale='None' format='sec' value=10.0>, azimuth=<Quantity 180. deg>, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)[source]

Instantiates a Pointing object around a source transit. The next transit at a given azimuth is search from t_min. The pointing is then centered at the transit, for a duration period. The pointing is made in steps numbered as duration/dt.

Parameters:

target (Target) – Celestial source target transiting.
t_min (Time) – Time from which the next transit is searched for.
duration (TimeDelta) – Total duration of the pointing, centered on the transit time. Default is one hour.
dt (TimeDelta) – Time steps of individual pointings. Default is 10 sec.
azimuth (Quantity) – Azimuth at which the transit is computed. A ValueError exception is raised if the selected target does not cross the required azimuth value. Default is 180 deg (i.e., South).
observer (EarthLocation) – Earth location from where the target is observed. Default is NenuFAR’s location.

Returns:

Pointing centered around a given target transit.

Return type:

Pointing

Example:

>>> from nenupy.astro.pointing import Pointing
>>> from astropy.time import Time, TimeDelta
>>> pointing = Pointing.target_transit(
        target=cyg_a,
        time=Time("2021-01-01 00:00:00"),
        duration=TimeDelta(7200, format="sec"),
        azimuth=180*u.deg
    )

property time

Pointing start times.

Setter:: Pointing times.
Getter:: Pointing times.
Type:: Time

classmethod zenith_tracking(time, duration=None, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)[source]

Instantiates a Pointing object at the local zenith.

Parameters:

time – Start times of the zenith pointing.
duration (TimeDelta) – Duration of each individual pointing. If this argument is a scalar, then it will be applied to every start time (defined in time). Default is one hour.
observer (EarthLocation) – Earth location from where the target is observed. Default is NenuFAR’s location.

Returns:

Pointing fixed at the local zenith.

Return type:

Pointing

Example:

>>> from nenupy.astro.pointing import Pointing
>>> from astropy.time import Time, TimeDelta
>>> pointing = Pointing.target_transit(
        target=cyg_a,
        time=Time("2021-01-01 00:00:00"),
        duration=TimeDelta(7200, format="sec"),
        azimuth=180*u.deg
    )