calibration Package

astro_calibration_source Module

Created on Aug 20, 2015

author: cchang

Models taken from: Baars 1997, Hafez 2008, Benz 2009 All numbers divided by 2 to account for the fact that our data is single polarization.

seek.calibration.astro_calibration_source.barrs77_power_law(freq, a, b, c)

Power law model from Baars 1997.

Parameters:

• freq – frequency in Hz
• a – model parameter
• b – model parameter
• c – model parameter

Returns:

model spectra

seek.calibration.astro_calibration_source.benz_sun(freq)

Model of Solar spectra based on Benz 2009.

Parameters:freq – frequency in Hz Returns:model spectra

seek.calibration.astro_calibration_source.black_body(freq, T)

Black body model spectra

Parameters:

• freq – frequency in Hz
• T – temperature of black body

Returns:

model spectra

seek.calibration.astro_calibration_source.source(obj, freq)

Given name of calibration source and frequency grid, give model spectrum.

fitting Module

Created on Aug 18, 2015

author: cchang

seek.calibration.fitting.fit_func(x, y, func_name, p0)

Fit different functions to curve. The current choices for functions are single or double Gaussians plus a linear background.

seek.calibration.fitting.gauss2(x, a_1, x0_1, sigma_1, a_2, x0_2, sigma_2, b, c)

Double Gaussian model plus a linear background.

flux_calibration_transit Module

Created on Feb 4, 2016

author: cchang

class seek.calibration.flux_calibration_transit.CalibrationSource(date, azimut, elevation, target)

Bases: tuple

azimut

Alias for field number 1

date

Alias for field number 0

elevation

Alias for field number 2

target

Alias for field number 3

class seek.calibration.flux_calibration_transit.GaussFitResult(gauss_A, gauss_x0, gauss_sigma, sky1, sky2, gauss_A_err, gauss_x0_err, gauss_sigma_err, sky1_err, sky2_err, rsquared)

Bases: tuple

gauss_A

Alias for field number 0

gauss_A_err

Alias for field number 5

gauss_sigma

Alias for field number 2

gauss_sigma_err

Alias for field number 7

gauss_x0

Alias for field number 1

gauss_x0_err

Alias for field number 6

rsquared

Alias for field number 10

sky1

Alias for field number 3

sky1_err

Alias for field number 8

sky2

Alias for field number 4

sky2_err

Alias for field number 9

seek.calibration.flux_calibration_transit.calibrate(ctx, plot=False)

Main function that performs the calibration, including the following steps:

• loop through the calibration sources

  – find the corresponding list of files

  —RFI removal

  – for each frequency fit 1D Gaussian to data

  —divide amplitude by reference spectra

  – store the final pseudo-gain value

• take median pseudo-gain over all calibration sources

• fit this final spectra with a template derived from Sun

• store this final fit to memory

Parameters:ctx – context that contains all parameters for RFI removal and file paths Returns:2D array with first column frequency and second gain factor

seek.calibration.flux_calibration_transit.fit_gaussian_source(data, time_axis, rfi_mask, source_dec, ctx)

Given a chunck of 2D data, fit a 1D Gaussian to each frequency. Here only return the amplitude.

Parameters:

• data – data
• time_axis – time axis
• rfi_mask – mask
• source_dec – declination coordinate of source
• ctx – context

Returns:

amplitude of Gaussian fit

seek.calibration.flux_calibration_transit.fit_gaussian_source_full(data, time_axis, rfi_mask, source_dec, params)

Given a chunck of 2D data, fit a 1D Gaussian to each frequency. Here return all fitted parameters.

Parameters:

• data – data
• time_axis – time axis
• rfi_mask – mask
• source_dec – declination coordinate of source
• params – context parameters

Returns:

all Gaussian fit parameters

seek.calibration.flux_calibration_transit.fit_sun_to_gain(gauss_amp, freq, params)

Takes the array of Gaussian fit parameters and fits the sun template to it. Then calculate the actual gain that converts the map ADU to K.

seek.calibration.flux_calibration_transit.process_calibration_transits(calibration_paths, ctx)

Derive gain as a function of frequency for each transit measurement.

Parameters:

• calibration_paths – path for calibration files
• ctx – context

Returns:

gain as a function of frequency

seek.calibration.flux_calibration_transit.process_source(source, file_paths, gain_template, sm_kwargs, di_kwargs, ctx)

Process a single transit measurement.

Parameters:

• source – name of source
• file_paths – file path
• gain_template – template derived from the Sun
• sm_kwargs – SumThreshold parameters
• di_kwargs – SumThreshold parameters
• ctx – context

Returns:

parameters for Gaussian fit