Utilities (photometry.utilities)

Collection of utility functions that can be used throughout the photometry package.

Code author: Rasmus Handberg <rasmush@phys.au.dk>

photometry.utilities.add_proper_motion(ra, dec, pm_ra, pm_dec, bjd, epoch=2000.0)[source]

Project coordinates (ra,dec) with proper motions to new epoch.

Parameters:
  • ra (float) – Right ascension.
  • dec (float) – Declination.
  • pm_ra (float) – Proper motion in RA (mas/year).
  • pm_dec (float) – Proper motion in Declination (mas/year).
  • bjd (float) – Julian date to calculate coordinates for.
  • epoch (float, optional) – Epoch of ra and dec. Default=2000.
Returns:

RA and Declination at the specified date.

Return type:

(float, float)

photometry.utilities.cartesian_to_radec(xyz)[source]

Convert cartesian coordinates (x,y,z) to spherical coordinates in ra-dec form.

Parameters:radec (ndarray) – Array with ra-dec pairs.
Returns:ra-dec coordinates in degrees corresponding to input coordinates.
Return type:ndarray
photometry.utilities.download_file(url, destination)[source]

Download file from URL and place into specified destination.

Parameters:
  • url (string) – URL to file to be downloaded.
  • destination (string) – Path where to save file.

Code author: Rasmus Handberg <rasmush@phys.au.dk>

photometry.utilities.find_catalog_files(rootdir, sector=None, camera=None, ccd=None)[source]

Search the input directory for CATALOG (sqlite) files matching constraints.

Parameters:
  • rootdir (string) – Directory to search for CATALOG files.
  • sector (integer, list or None, optional) – Only return files from the given sectors. If None, files from all TIC numbers are returned.
  • camera (integer, list or None, optional) – Only return files from the given camera. If None, files from all cameras are returned.
  • ccd (integer, list or None, optional) – Only return files from the given ccd. If None, files from all ccds are returned.
Returns:

List of paths to CATALOG files matching constraints.

Return type:

list

photometry.utilities.find_ffi_files(rootdir, sector=None, camera=None, ccd=None)[source]

Search directory recursively for TESS FFI images in FITS format.

Parameters:
  • rootdir (string) – Directory to search recursively for TESS FFI images.
  • sector (integer or None, optional) – Only return files from the given sector. If None, files from all sectors are returned.
  • camera (integer or None, optional) – Only return files from the given camera number (1-4). If None, files from all cameras are returned.
  • ccd (integer or None, optional) – Only return files from the given CCD number (1-4). If None, files from all CCDs are returned.
Returns:

List of full paths to FFI FITS files found in directory. The list will

be sorted accoridng to the filename of the files, e.g. primarily by time.

Return type:

list

photometry.utilities.find_hdf5_files(rootdir, sector=None, camera=None, ccd=None)[source]

Search the input directory for HDF5 files matching constraints.

Parameters:
  • rootdir (string) – Directory to search for HDF5 files.
  • sector (integer, list or None, optional) – Only return files from the given sectors. If None, files from all TIC numbers are returned.
  • camera (integer, list or None, optional) – Only return files from the given camera. If None, files from all cameras are returned.
  • ccd (integer, list or None, optional) – Only return files from the given ccd. If None, files from all ccds are returned.
Returns:

List of paths to HDF5 files matching constraints.

Return type:

list

photometry.utilities.find_nearest(array, value)[source]

Search array for value and return the index where the value is closest.

Parameters:
  • array (ndarray) – Array to search.
  • value – Value to search array for.
Returns:

Index of array closest to value.

Return type:

int

Code author: Rasmus Handberg <rasmush@phys.au.dk>

photometry.utilities.find_tpf_files(rootdir, starid=None, sector=None, camera=None, ccd=None, findmax=None)[source]

Search directory recursively for TESS Target Pixel Files.

Parameters:
  • rootdir (string) – Directory to search recursively for TESS TPF files.
  • starid (integer or None, optional) – Only return files from the given TIC number. If None, files from all TIC numbers are returned.
  • sector (integer or None, optional) – Only return files from the given sector. If None, files from all sectors are returned.
  • camera (integer or None, optional) – Only return files from the given camera number (1-4). If None, files from all cameras are returned.
  • ccd (integer or None, optional) – Only return files from the given CCD number (1-4). If None, files from all CCDs are returned.
  • findmax (integer or None, optional) – Maximum number of files to return. If None, return all files.

Note

Filtering on camera and/or ccd will cause the program to read the headers of the files in order to determine the camera and ccd from which they came. This can significantly slow down the query.

Returns:
List of full paths to TPF FITS files found in directory. The list will
be sorted accoriding to the filename of the files, e.g. primarily by time.
Return type:list
photometry.utilities.integratedGaussian(x, y, flux, x_0, y_0, sigma=1)[source]

Evaluate a 2D symmetrical Gaussian integrated in pixels.

Parameters:
  • x (numpy array) – x coordinates at which to evaluate the PSF.
  • y (numpy array) – y coordinates at which to evaluate the PSF.
  • flux (float) – Integrated value.
  • x_0 (float) – Centroid position.
  • y_0 (float) – Centroid position.
  • sigma (float, optional) – Standard deviation of Gaussian. Default=1.
Returns:

2D Gaussian integrated pixel values at (x,y).

Return type:

numpy array

Example:

>>> import numpy as np
>>> X, Y = np.meshgrid(np.arange(-1,2), np.arange(-1,2))
>>> integratedGaussian(X, Y, 10, 0, 0)
array([[ 0.58433556,  0.92564571,  0.58433556],
        [ 0.92564571,  1.46631496,  0.92564571],
        [ 0.58433556,  0.92564571,  0.58433556]])
photometry.utilities.load_ffi_fits(path, return_header=False, return_uncert=False)[source]

Load FFI FITS file.

Calibrations columns and rows are trimmed from the image.

Parameters:
  • path (str) – Path to FITS file.
  • return_header (boolean, optional) – Return FITS headers as well. Default is False.
Returns:

Full Frame Image. list: If return_header is enabled, will return a dict of the FITS headers.

Return type:

numpy.ndarray

photometry.utilities.load_settings(sector=None)[source]
photometry.utilities.mag2flux(mag)[source]

Convert from magnitude to flux using scaling relation from aperture photometry. This is an estimate.

The scaling is based on fast-track TESS data from sectors 1 and 2.

Parameters:mag (float) – Magnitude in TESS band.
Returns:Corresponding flux value
Return type:float
photometry.utilities.move_median_central(x, width_points, axis=0)[source]
photometry.utilities.radec_to_cartesian(radec)[source]

Convert spherical coordinates as (ra, dec) pairs to cartesian coordinates (x,y,z).

Parameters:radec (ndarray) – Array with ra-dec pairs in degrees.
Returns:(x,y,z) coordinates corresponding to input coordinates.
Return type:ndarray
photometry.utilities.rms_timescale(time, flux, timescale=0.041666666666666664)[source]

Compute robust RMS on specified timescale. Using MAD scaled to RMS.

Parameters:
  • time (ndarray) – Timestamps in days.
  • flux (ndarray) – Flux to calculate RMS for.
  • timescale (float, optional) – Timescale to bin timeseries before calculating RMS. Default=1 hour.
Returns:

Robust RMS on specified timescale.

Return type:

float

Code author: Rasmus Handberg <rasmush@phys.au.dk>

photometry.utilities.sphere_distance(ra1, dec1, ra2, dec2)[source]

Calculate the great circle distance between two points using the Vincenty formulae.

Parameters:
  • ra1 (float or ndarray) – Longitude of first point in degrees.
  • dec1 (float or ndarray) – Lattitude of first point in degrees.
  • ra2 (float or ndarray) – Longitude of second point in degrees.
  • dec2 (float or ndarray) – Lattitude of second point in degrees.
Returns:

Distance between points in degrees.

Return type:

ndarray

photometry.utilities.mad_to_sigma = 1.482602218505602

Constant for converting from MAD to SIGMA. Constant is 1/norm.ppf(3/4)