Python functions

Python functions for PhD work.

Polarization

• compute the polarized intensity and its uncertainty
• compute the polarization angle and its uncertainty
• compute the polarization fraction and its uncertainty
• compute the de-biased polarized intensity
• compute the polarization gradient (with and without cross-terms)
• compute the normalized polarization gradient (with and without cross-terms)
• compute the argument of polarization gradient (with and without cross-terms)
• apply a mask to the argument of polarization gradient
• compute the radial and tangential components of the polarization gradient
• compute the angular version of the polarization gradient
• compute the plane-of-sky magnetic field orientation
• compute an estimate of the polarization angle dispersion function
• compute the de-rotated magnetic field orientation
• create a dictionary of polarization gradient arguments for each pixel
• plot an image with pseudovectors overlaid
• compute the rotation measure structure function (RMSF) and related parameters
• compute the first moment of a one-dimensional Faraday dispersion function
• compute the second moment of a one-dimensional Faraday dispersion function
• compute the first moment map of a three-dimensional Faraday dispersion function
• compute the second moment map of a three-dimensional Faraday dispersion function

FITS files

• construct the frequency axis of a 3D FITS file
• compute the average across a data cube's third axis
• compute the summation of a list of 2D FITS files
• create a grid of equatorial coordinates for a FITS file
• create a grid of Galactic coordinates for a FITS file
• transform a coordinate grid from equatorial to Galactic coordinates
• transform a coordinate grid from Galactic to equatorial coordinates
• reproject one 2D FITS image to another
• reproject one 3D FITS image to another
• reproject a 2D FITS image from equatorial to Galactic coordinates
• reproject a 3D FITS image from equatorial to Galactic coordinates
• reproject a 2D FITS image from Galactic to equatorial coordinates
• reproject a 3D FITS image from Galactic to equatorial coordinates
• reproject a HEALPix image to a standard FITS projection
• creates a mask using a condition on Galactic latitude
• masks a 2D FITS image in equatorial coordinates based on Galactic latitude
• transform a 3D FITS header to a 2D FITS header
• slice a 3D FITS data cube along its third axis and save each 2D image as a separate FITS image

Sky Coordinates

• transform Right Ascension and Declination coordinates from decimal degrees to the sexagismal system
• transform Right Ascension and Declination coordinates from the sexagismal system to decimal degrees
• precess Right Ascension and Declination coordinates from the sexagismal system in the B1959 equinox to decimal degrees in the J2000 equinox
• match two sets of catalogue positions in equatorial coordinates
• write a set of cooridinates to an annotation file for kvis
• write a set of cooridinates to a region file for ds9

Photometry

• convert photometric magnitude uncertainty to signal-to-noise ratio
• convert photometric signal-to-noise ratio to magnitude uncertainty
• convert AB magnitudes to the Vega magnitude scale
• compute photometric colour and its uncertainty
• compute J-, H-, and K-band extinctions using the RJCE technique
• compute J-, H-, and K-band intrinsic magnitudes using the RJCE technique
• compute J-, H-, and K-band distance-corrected luminosities using Gaia parallaxes
• compute distance using Gaia parallax

Rolling Hough Transform

See the Rolling Hough Transform.

• execute the RHT on all FITS files within a given directory
• add contents of a FITS image header to an RHT FITS file
• collect all RHT angles for each spatial pixel in the image plane
• compute the distribution in RHT angle differences between two images
• compute the RHT backprojection allowing one to mask specific angles

Planck

• converts Planck Stokes maps from K_CMB to MJy/sr
• converts Planck Stokes maps from uK to MJy/sr
• remove the CMB monopole from the Planck 353 GHz Stokes maps
• add the Galactic HI offset correction to the Planck 353 GHz Stokes I map

Line Integral Convolution (LIC)

• compute magnetic field orientation in IAU convention
• compute LIC texture
• overplot LIC texture on an image

Colormaps

• twilight colormap
• Planck frequency colormap
• Planck parchment colormap

Miscellaneous

• convert frequency to wavelength
• convert wavelength to frequency
• compute upper limit kinetic temperature from line broadening
• mask a 2D FITS image in signal
• mask a 2D FITS image in signal-to-noise
• compute the 1D and 2D fast Fourier transform (FFT)
• compute the 1D and 2D inverse fast Fourier transform (IFFT)
• compute the 2D spatial gradient of an image
• map angles defined on the polar plane [0,2pi) to the half polar plane [0,pi)
• compute the angular difference between two angles defined on the half-polar plane
• convolve a 2D FITS image using FFT convolution
• reads in a ROHSA data file
• mask and interpolate over point sources
• applies a mask to a 2D FITS image and interpolates
• mask an image within the boundary of a circle
• mask an image within the boundary of an ellipse
• mask an image betweeen two lines
• masks basketweaving artefacts of the GALFACTS sensitivity map FFT