SkyFitter

class ctapointing.imagesolver.SkyFitter(**kwargs: Any)

Bases: Component

Sky fitting class

Fits a list of spots to matched stars using the full transformation tree or an astropy WCS transformation

Attributes Summary

`distance_goal`	fit distance goal
`fit_camera_distortion`	fit camera distortion parameters
`fixed_parameters`	list of parameters fixed during fitting
`max_num_fit_iterations`	maximum number of fit iterations
`name`	name of SkyFitter
`residual_cut`	cut value for spot outlier removal
`uuid`	UUID of SkyFitter

Methods Summary

`from_config`(**kwargs)	Read a SkyFitter configuration from either configuration file or database.
`process`(spot_star_match_list, exposure[, ...])	Fit a list of spots to pre-matched stars to find the transformation parameters for coordinate transformations from pixel coordinates to sky coordinates.

Attributes Documentation

distance_goal: fit distance goal

fit_camera_distortion: fit camera distortion parameters

fixed_parameters: list of parameters fixed during fitting

max_num_fit_iterations: maximum number of fit iterations

name: name of SkyFitter

residual_cut: cut value for spot outlier removal

uuid: UUID of SkyFitter

Methods Documentation

classmethod from_config(**kwargs)

Read a SkyFitter configuration from either configuration file or database. Either the path of a configuration file (‘input_url’) or a database collection (‘collection’) must be provided.

Parameters:

input_url (str or Path) – path of the configuration file.
name (str) – name of the SpotExtractor (as in SkyFitter.name). When loading the configuration from file, can be set to check that the configuration with the correct name is loaded. When loading from database, is used to identify the correct database record.
uuid (str) – UUID of the camera (as in PointingCamera.uuid). When loading the configuration from file, can be set to check that the configuration with the correct UUID is loaded. When loading from database, is used to identify the correct database record.
collection (str) – name of the database collection from which configuration is read
database (str) – name of the database in which the collection is stored

Returns:

fitter

Return type:

SkyFitter object or None

process(spot_star_match_list, exposure, estimated_pointing=None, distortion_correction=None, image_solution=None)

Fit a list of spots to pre-matched stars to find the transformation parameters for coordinate transformations from pixel coordinates to sky coordinates.

The fit uses the full (non-idealised) set of coordinate transformations, taking into account refraction effects in the atmosphere and lens distortion.

Parameters:

spot_star_match_list (list) – list of StarSpotMatch objects that contain information about the pre-matched spot-star pairs
exposure (Exposure) – exposure object, holding information about the actual exposure (camera properties etc.)
estimated_pointing (astropy.SkyCoord) – estimated telescope pointing position (in the ICRS frame)
image_solution (ctapointing.imagesolver.ImageSolution) – image solution object that is updated with fit results. If None, a new object is created.

Returns:

solution (ImageSolution) – ImageSolution object containing summary information on the result
m (iminuit.minuit) – minuit object for the sky -> pixels fit
m_inv (iminuit.minuit) – minuit object for the pixel -> intermediate pixel coordinates fit

distance_goal: fit distance goal

fit_camera_distortion: fit camera distortion parameters

fixed_parameters: list of parameters fixed during fitting

classmethod from_config(**kwargs)

Read a SkyFitter configuration from either configuration file or database. Either the path of a configuration file (‘input_url’) or a database collection (‘collection’) must be provided.

Parameters:

input_url (str or Path) – path of the configuration file.
name (str) – name of the SpotExtractor (as in SkyFitter.name). When loading the configuration from file, can be set to check that the configuration with the correct name is loaded. When loading from database, is used to identify the correct database record.
uuid (str) – UUID of the camera (as in PointingCamera.uuid). When loading the configuration from file, can be set to check that the configuration with the correct UUID is loaded. When loading from database, is used to identify the correct database record.
collection (str) – name of the database collection from which configuration is read
database (str) – name of the database in which the collection is stored

Returns:

fitter

Return type:

SkyFitter object or None

max_num_fit_iterations: maximum number of fit iterations

name: name of SkyFitter

process(spot_star_match_list, exposure, estimated_pointing=None, distortion_correction=None, image_solution=None)

Fit a list of spots to pre-matched stars to find the transformation parameters for coordinate transformations from pixel coordinates to sky coordinates.

The fit uses the full (non-idealised) set of coordinate transformations, taking into account refraction effects in the atmosphere and lens distortion.

Parameters:

spot_star_match_list (list) – list of StarSpotMatch objects that contain information about the pre-matched spot-star pairs
exposure (Exposure) – exposure object, holding information about the actual exposure (camera properties etc.)
estimated_pointing (astropy.SkyCoord) – estimated telescope pointing position (in the ICRS frame)
image_solution (ctapointing.imagesolver.ImageSolution) – image solution object that is updated with fit results. If None, a new object is created.

Returns:

solution (ImageSolution) – ImageSolution object containing summary information on the result
m (iminuit.minuit) – minuit object for the sky -> pixels fit
m_inv (iminuit.minuit) – minuit object for the pixel -> intermediate pixel coordinates fit

residual_cut: cut value for spot outlier removal

uuid: UUID of SkyFitter