nenupy.astro.pointing

Pointing

Pointing(coordinates, time[, duration, observer])

Class to handle instrument pointing.

class nenupy.astro.pointing.Pointing(coordinates, time, duration=<TimeDelta object: scale='None' format='sec' value=1.0>, 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

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

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=<TimeDelta object: scale='None' format='sec' value=3600.0>, 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). Default is one hour.
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=<TimeDelta object: scale='None' format='sec' value=1.0>, 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
    )