LazuliFlat

LazuliFlat#

class LazuliFlat(lbda, flux, amplitude=1, **kwargs)[source]#

Bases: VirtualLazuliTarget, Target

A spatially uniform source observed with Lazuli.

The scene contains neither point source nor host: the input spectrum is used as a spatially flat background filling the field.

Warning

Instantiation currently fails with a TypeError, as the parent initialisation resolves to Target, which expects lbda and flux. See Lazuli3DFlat for flat-field calibration exposures.

Parameters:

lbda (array_like) – Wavelengths in Angstrom of the reference spectrum.
flux (array_like) – Flux of the reference spectrum, in erg/s/cm^2/A per spaxel.
amplitude (float, optional) – Scaling factor applied to flux. It is a mutable parameter of the scene, so the flat level can be changed afterwards without rebuilding the target. Default is 1.
**kwargs – Goes to from_config.

Methods

`change_configuration`	Change the Lazuli instrument configuration.
`change_detector`	Change the detector read-out configuration.
`change_properties`	Change any mutable parameter of the simulation.
`change_spectrograph`	Change the spectrograph configuration.
`from_scene`	Load the instance from a scene configuration.
`from_simulation`	Load the instance from an already-built simulation.
`get_band_snr`	Get the signal-to-noise ratio over a wavelength range.
`get_cube`	Get the simulated cubes, for one or both Lazuli fields.
`get_data_volume`	Get the data volume of the observation.
`get_detector_image`	Project the narrow and wide field cubes onto a single detector image.
`get_exposure_time`	Get the exposure time of the current configuration.
`get_properties`	Get parameter values of the target's simulation.
`get_readout_config`	Get the current MACC mode and number of ramps.
`get_spectrograph_field`	Get the current spectrograph field.
`get_spectrum`	Get the simulated spectrum of the point source.
`get_variance_contribution`	Get the contribution of each noise source to the variance.
`setup_to_snr`	Find the detector read-out configuration reaching a target SNR.
`to_image`	Project the narrow and wide field cubes onto a single detector image.

Attributes

`pointsource_properties`	Names of the mutable parameters of the point source (list of str).
`simulation`	The `Simulation` wrapped by the target.

change_configuration(which)#

Change the Lazuli instrument configuration.

The corresponding configuration file (lazuli_eol.toml or lazuli_cbe.toml) is read and the simulation updated with it.

Parameters:: which (str) – Name of the configuration: "eol" (end of life) or "cbe" (current best estimate); "bol" (beginning of life) is an alias of "cbe".
Returns:: None

change_detector(nmd=None, max_group=None, nramps=None)#

Change the detector read-out configuration.

Parameters set to None are left unchanged.

Parameters:

nmd (tuple of int, optional) – MACC mode (n_groups, n_frames_per_group, n_drops). Default is None.
max_group (int, optional) – Maximum number of groups in a single ramp. Default is None.
nramps (int, optional) – Number of ramps. Default is None.

Returns:

None

change_properties(**kwargs)#

Change any mutable parameter of the simulation.

Shortcut to update.

Parameters:: **kwargs – The parameters to change, as name=value (e.g. redshift=0.5 or pointsource__phase=-2).
Returns:: None

change_spectrograph(field=None, spatial_shape=None, spatial_scale=None)#

Change the spectrograph configuration.

Parameters:

field (str, optional) –
Lazuli field to use (see SPECTROGRAPH_FIELD):
- "narrow": finely sampled field, with 0.04 arcsec spaxels.
- "wide": coarser field, with 0.08 arcsec spaxels.
If None, only spatial_shape and spatial_scale are applied. Default is None.
spatial_shape (tuple of int, optional) – Spaxel grid shape (e.g. (40, 40)), overriding that of field if any. Default is None.
spatial_scale (float or list of float, optional) – Spaxel size in arcsec, overriding that of field if any. If a float, spaxels are square; if a list, (x, y). Default is None.

Returns:

None

Raises:

ValueError – If field is not a known Lazuli field.

classmethod from_scene(scene=None, **kwargs)#

Load the instance from a scene configuration.

Parameters:

scene (dict or str, optional) –

Scene configuration (see get_scene), in the format:

scene = {"scene": {"pointsource": {},  # PSF
                   "background": {},   # spatially flat
                   "host": {}}}        # structured background

or the name of a scene configuration file. Default is None.

**kwargs – Goes to get_config, overriding the scene and the Lazuli instrument configuration.

Returns:

VirtualLazuliTarget – An instance of the class.

classmethod from_simulation(simulation)#

Load the instance from an already-built simulation.

Warning

This override is currently broken and always raises TypeError: super().__init__ is called from a classmethod, so no instance is ever built. It shadows the working from_simulation for Target and its subclasses.

Parameters:: simulation (slicersim.simulation.Simulation) – The simulation the target wraps.
Returns:: Target – An instance of the class, once the implementation is fixed.
Raises:: TypeError – Always, see the warning above.

get_band_snr(lbda_range, frame='obs', per_resolution=True, statistic=<function nanmean>, **kwargs)#

Get the signal-to-noise ratio over a wavelength range.

Parameters:

lbda_range (tuple of float or list of tuple) – Wavelength range (min, max) in Angstrom (or a list of them).
frame (str, optional) – Reference frame of lbda_range: "rest" or "obs". Default is "obs".
per_resolution (bool, optional) – If True, return the SNR per spectral resolution element, otherwise per wavelength bin. Default is True.
statistic (callable, optional) – Function used to summarise the signal and variance over lbda_range. Default is numpy.nanmean.
**kwargs – Goes to get_band_snr (e.g. switch_off).

Returns:

float or numpy.ndarray – The SNR, one per wavelength range if a list is given. If any detector pixel saturates, numpy.inf is returned.

get_cube(which='both', **kwargs)#

Get the simulated cubes, for one or both Lazuli fields.

Parameters:

which (str, optional) –
Which cube should be computed:
- "both": both narrow and wide fields.
- "current": only the current setup.
- "narrow": only the narrow field.
- "wide": only the wide field.
Default is "both".
**kwargs – Goes to get_cube.

Returns:

tuple – (cube, varcube), the cube (ADU) and variance cube (ADU^2) of the requested field, or, if which="both", ((cube_narrow, varcube_narrow), (cube_wide, varcube_wide)).

Raises:

ValueError – If which is not "current" while the spectrograph is set up neither as the narrow nor the wide field.
NotImplementedError – If the scene contains a host (not yet supported).

Notes

When switching field, the point source position is converted to the spaxel units of the other field. The original spectrograph setup and position are restored afterwards.

get_data_volume(units='GB', per_ramp=False)#

Get the data volume of the observation.

Parameters:

units (str, optional) – Unit of the returned volume (any astropy data unit, e.g. "MB" or "GB"). Default is "GB".
per_ramp (bool, optional) – If True, return the volume of a single ramp instead of the total volume over all ramps. Default is False.

Returns:

float – Data volume in units.

LazuliFlat

Contents

LazuliFlat#