# tkp.telescope – Telescope specific functionality¶

## tkp.telescope.lofar¶

Functions for calculating LOFAR hardware specific properties.

This module contains numbers of phsysicial properties of the LOFAR array.

For performance reasons these distances are precomputed. One can recompute them using parse_antennafile(), shortest_distances() and a AntennaArrays.conf file from LOFAR/MAC/Deployment/data/StaticMetaData/AntennaArrays in the lofar system software source tree.

tkp.telescope.lofar.antennaarrays.parse_antennafile(positions_file)[source]

Parses an antenna file from the LOFAR system software repository.

Parameters: positions_file – a antenna file a dictionary with array as key and positions as values
tkp.telescope.lofar.antennaarrays.pretty_print(file_)[source]

Pretty prints a parsed antenna file. Use this function to generate copy paste code to be used in the top of this file.

Parameters: file – a file location
tkp.telescope.lofar.antennaarrays.shortest_distances(coordinates, full_array)[source]

returns a list of distances for each antenna relative to its closest neighbour.

Parameters: coordinates – a list of 3 value tuples that represent x,y and z coordinates of a subset of the array full_array – a list of x,y,z coordinates of a full array a list of floats of distances

Beam characterization calculations.

For more information and the math behind this code go to the LOFAR imaging capabilities page.

tkp.telescope.lofar.beam.fov(fwhm)[source]

The Field of View (FoV) of a LOFAR station

Parameters: fwhm – nominal Full Width Half Maximum, caulculated with fwhm().
tkp.telescope.lofar.beam.fwhm(lambda_, d, alpha1=1.3)[source]

The nominal Full Width Half Maximum (FWHM) of a LOFAR Station beam.

Parameters: lambda – wavelength in meters d – station diameter. alpha1 – depends on the tapering intrinsic to the layout of the station, and any additional tapering which may be used to form the station beam. No electronic tapering is presently applied to LOFAR station beamforming. For a uniformly illuminated circular aperture, alpha1 takes the value of 1.02, and the value increases with tapering (Napier 1999). the nominal Full Width Half Maximum (FWHM)

functions for calculating theoretical noise levels of LOFAR equipment.

To check the values calculated here one can use this LOFAR image noise calculator.

tkp.telescope.lofar.noise.Aeff_dipole(freq_eff, distance=None)[source]

The effective area of each dipole in the array is determined by its distance to the nearest dipole (d) within the full array.

Parameters: freq_eff – Frequency distance – Distance to nearest dipole, only required for LBA.
tkp.telescope.lofar.noise.noise_level(freq_eff, bandwidth, tau_time, antenna_set, Ncore, Nremote, Nintl)[source]

Returns the theoretical noise level (in Jy) given the supplied array antenna_set.

Parameters: bandwidth – in Hz tau_time – in seconds inner – in case of LBA, inner or outer antenna_set – LBA_INNER, LBA_OUTER, LBA_SPARSE, LBA or HBA
tkp.telescope.lofar.noise.system_sensitivity(freq_eff, Aeff)[source]

Returns the SEFD of a system, given the freq_eff and effective collecting area. Returns SEFD in Jansky’s.