hera_sim.foregrounds.DiffuseForeground¶

class hera_sim.foregrounds.DiffuseForeground(Tsky_mdl=None, omega_p=None, delay_filter_kwargs=None, fringe_filter_kwargs=None, rng=None)[source]¶

Produce a rough simulation of diffuse foreground-like structure.

Parameters:

Tsky_mdl (interpolation object) – Sky temperature model, in units of Kelvin. Must be callable with signature Tsky_mdl(lsts, freqs), formatted so that lsts are in radians and freqs are in GHz.
omega_p (interpolation object or array-like of float) – Beam size model, in units of steradian. If passing an array, then it must be the same shape as the frequency array passed to the freqs parameter.
delay_filter_kwargs (dict, optional) – Keyword arguments and associated values to be passed to rough_delay_filter(). Default is to use the following settings: standoff : 0.0, delay_filter_type : tophat.
fringe_filter_kwargs (dict, optional) – Keyword arguments and associated values to be passed to rough_fringe_filter(). Default is to use the following settings: fringe_filter_type : tophat.
rng (np.random.Generator, optional) – Random number generator.

Notes

This algorithm provides a rough simulation of visibilities from diffuse foregrounds by using a sky temperature model. The sky temperature models provided in this package are appropriate for the HERA H1C observing season, and are only valid for frequencies between 100 MHz and 200 MHz; anything beyond this range is just a copy of the value at the nearest edge. Simulated autocorrelations (i.e. zero magnitude bl_vec) are returned as complex arrays, but have zero imaginary component everywhere. For cross-correlations, the sky model is convolved with white noise (in delay/fringe-rate space), and rough delay and fringe filters are applied to the visibility. As a standalone component model, this is does not produce consistent simulated visibilities for baselines within a redundant group (except for autocorrelations); however, the Simulator class provides the functionality to ensure that redundant baselines see the same sky. Additionally, visibilities simulated with this model are not invariant under complex conjugation and baseline conjugation, since the delay filter applied is symmetric; however, the Simulator class is aware of this and ensures invariance under complex conjugation and baseline conjugation.

Methods

`__call__`(lsts, freqs, bl_vec, **kwargs)	Compute the foregrounds.
`get_aliases`()	Get all the aliases by which this model can be identified.
`get_model`(mdl)	Get a model with a particular name (including aliases).
`get_models`([with_aliases])	Get a dictionary of models associated with this component.

Attributes

`attrs_to_pull`	Mapping between parameter names and Simulator attributes
`is_multiplicative`	Whether this systematic multiplies existing visibilities
`is_randomized`	Whether this systematic contains a randomized component
`is_smooth_in_freq`
`return_type`	Whether the returned value is per-antenna, per-baseline, or the full array