nenupy.astro.sky.Sky

class nenupy.astro.sky.Sky(coordinates, time=<Time object: scale='utc' format='datetime' value=2026-05-27 13:14:46.546762>, frequency=<Quantity 50. MHz>, polarization=array([0]), value=0.0, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)

Bases: AstroObject

__init__(coordinates, time=<Time object: scale='utc' format='datetime' value=2026-05-27 13:14:46.546762>, frequency=<Quantity 50. MHz>, polarization=array([0]), value=0.0, observer=<EarthLocation (4323936.68522791, 165534.49991696, 4670345.36540385) m>)

Methods

__init__(coordinates[, time, frequency, ...])
compute_lmn(phase_center[, coordinate_mask])	(l, m, n) image domain coordinates computed from HEALPix equatorial coordinates (in Right-Ascension \(\alpha\) and Declination \(\delta\), see coordinates) with respect to the phase_center (of equatorial coordinates \(\alpha_0\), \(\delta_0\)).
hour_angle([fast_compute])
local_sidereal_time([fast_compute])

Attributes

custom_ho_coordinates	Allows to modify horizontal coordinates without messing up with the actual coordinates object.
frequency
ground_projection
horizontal_coordinates
polarization
shape
time
value
visible_mask
coordinates
observer

compute_lmn(phase_center, coordinate_mask=None)

(l, m, n) image domain coordinates computed from HEALPix equatorial coordinates (in Right-Ascension \(\alpha\) and Declination \(\delta\), see coordinates) with respect to the phase_center (of equatorial coordinates \(\alpha_0\), \(\delta_0\)).

\[\begin{split}\cases{ l = \cos(\delta) \sin( \Delta \alpha)\\ m = \sin(\delta) \cos(\delta_0) - \cos(\delta) \sin(\delta_0) \cos(\Delta \alpha)\\ n = \sqrt{ 1 - l^2 - m^2 } }\end{split}\]

where \(\Delta \alpha = \alpha - \alpha_0\).

Parameters:

• phase_center (SkyCoord) – Image phase center.

• coordinate_mask (ndarray) – Mask applied to coordinates before computing (l,m,n) values.

Returns:

(l, m, n)

Return type:

tuple of 3 ndarray

property custom_ho_coordinates

Allows to modify horizontal coordinates without messing up with the actual coordinates object.