pycrtools.tasks.galaxy

GalacticNoise([ws, parfile])	Task to normalize noise levels in both dipoles to the expected Galactic noise level and to apply calibration of dipoles as developed in master thesis Tijs Karskens.
Task([ws, parfile])	Base class from which all tasks should be derived.
calibratedGaincurve(freq, NrAntennas[, galaxy])	Function delivers calibration curve as:
interp1d(x, y[, kind, axis, copy, ...])	interp1d(x, y, kind=’linear’, axis=-1, copy=True, bounds_error=True,

Galaxy

Module author: Pim Schellart <p.schellart@astro.ru.nl>

class pycrtools.tasks.galaxy.GalacticNoise(ws=None, parfile=None, **kwargs)

Task to normalize noise levels in both dipoles to the expected Galactic noise level and to apply calibration of dipoles as developed in master thesis Tijs Karskens.

Evaluates a partial Fourier series fit to the Galactic response as a function of Local Apparant Siderial Time.

Multiplies the data with the calibration curve to physical units.

For example:

# Normalize recieved power to that expected for a Galaxy dominated reference antenna
galactic_noise = cr.trun("GalacticNoise", fft_data=fft_data, channel_width=f["SAMPLE_FREQUENCY"][0] / f["BLOCKSIZE"], timestamp=tbb_time, antenna_set=f["ANTENNA_SET"], original_power=antennas_cleaned_power)

See also

Schellart et al., Detecting cosmic rays with the LOFAR radio telescope, Astronomy and Astrophysics, 560, A98, (2013) and Nelles, Karskens, Krause et al., Calibration Paper in prep (2015).

Input parameters

antenna_set [default value: “” ]

Antenna set

channel_width [default value: 1.0 ]

Width of a single frequency channel in Hz

coefficients_hba

Tuple with coefficients for partial Fourier series describing galaxy response in Hz for polarization 0 and 1 respectively

coefficients_lba [default value: (array([ 0.01620088, -0.00143372,  0.00099162, -0.00027658, -0.00056887]), array([  1.44219822e-02,  -9.51155631e-04,   6.51046296e-04,         8.33650041e-05,  -4.91284500e-04])) ]

Tuple with coefficients for partial Fourier series describing galaxy response in Hz for polarization 0 and 1 respectively

fft_data [default value: None ]

FFT data to correct.

frequencies [default value: None ]

Frequencies in Hz.

longitude [default value: 0.11990128415 ]

Observer longitude in radians

original_power [default value: None ]

Original power to normalize by (typically rfi cleaned average integrated power spectrum per antenna).

timestamp [default value: None ]

Observation time

use_gain_curve [default value: False ]

Use gain curve to correct to physical units (Volts). Antenna model will add meters.

use_gain_galaxy [default value: False ]

Use gain curve from Galaxy to correct to physical units (Volts). Antenna model will add meters. If set False, the crane calibration will be used.

Output parameters

galactic_noise_power [default value: (0, 0) ]

Galactic noise power per Hz

fourier_series(x, p)

Evaluates a partial Fourier series

run()

Run.

pycrtools.tasks.galaxy.calibratedGaincurve(freq, NrAntennas, galaxy=True)

Function delivers calibration curve as:

Data * Calibration curve = Simulated voltage
                         = Expected electric field * Antenna model

Hence, it’s the gain-factor by which the data should be multiplied in order to match the expected voltages.