UVCal Parameters

These are the standard attributes of UVCal objects.

Under the hood they are actually properties based on UVParameter objects.

Required

These parameters are required to have a sensible UVCal object and are required for most kinds of uv cal files.

Nants_data
Number of antennas that have data associated with them (i.e. number of unique entries in ant_array). May be smaller than the number of antennas in the telescope
Nants_telescope
Number of antennas in the array. May be larger than the number of antennas with data
Nfreqs
Number of frequency channels
Njones
Number of Jones calibrationparameters (Number of Jones matrix elements calculated in calibration).
Nspws
Number of spectral windows (ie non-contiguous spectral chunks). More than one spectral window is not currently supported.
Ntimes
Number of times with different calibrations calculated (if a calibration is calculated over a range of integrations, this gives the number of separate calibrations along the time axis).
ant_array
Array of antenna indices for data arrays, shape (Nants_data), type = int, 0 indexed
antenna_names
List of antenna names, shape (Nants_telescope), with numbers given by antenna_numbers (which can be matched to ant_array). There must be one entry here for each unique entry in ant_array, but there may be extras as well.
antenna_numbers
List of integer antenna numbers corresponding to antenna_names, shape (Nants_telescope). There must be one entry here for each unique entry in ant_array, but there may be extras as well.
cal_type
cal type parameter. Values are delay, gain or unknown.
channel_width
Channel width of of a frequency bin. Units Hz.
flag_array
Array of flags to be applied to calibrated data (logical OR of input and flag generated by calibration). True is flagged. Shape: (Nants_data, Nspws, Nfreqs, Ntimes, Njones), type = bool.
freq_array
Array of frequencies, shape (Nspws, Nfreqs), units Hz.
gain_convention
The convention for applying the calibration solutions to data.Values are “divide” or “multiply”, indicating that to calibrate one should divide or multiply uncalibrated data by gains. Mathematically this indicates the alpha exponent in the equation: calibrated data = gain^alpha * uncalibrated data. A value of “divide” represents alpha=-1 and “multiply” represents alpha=1.
history
String of history, units English
integration_time
Integration time of a time bin, units seconds.
jones_array
Array of antenna polarization integers, shape (Njones). linear pols -5:-8 (jxx, jyy, jxy, jyx).circular pols -1:-4 (jrr, jll. jrl, jlr).
quality_array
Array of qualities of calibration solutions. The shape depends on cal_type, if the cal_type is “gain” or “unknown”, the shape is: (Nants_data, Nspws, Nfreqs, Ntimes, Njones), if the cal_type is “delay”, the shape is (Nants_data, Nspws, 1, Ntimes, Njones), type = float.
spw_array
Array of spectral window numbers, shape (Nspws).
telescope_name
Name of telescope. e.g. HERA. String.
time_array
Array of calibration solution times, center of integration, shape (Ntimes), units Julian Date
time_range
Time range (in JD) that cal solutions are valid for.list: [start_time, end_time] in JD.
x_orientation
Orientation of the physical dipole corresponding to what is labelled as the x polarization. Examples include “east” (indicating east/west orientation) and “north” (indicating north/south orientation)

Optional

These parameters are defined by one or more file standard but are not always required. Some of them are required depending on the cal_type (as noted below).

delay_array
Required if cal_type = “delay”. Array of delays with units of seconds. Shape: (Nants_data, Nspws, 1, Ntimes, Njones), type = float.
freq_range
Required if cal_type = “delay”. Frequency range that solutions are valid for.list: [start_frequency, end_frequency] in Hz.
gain_array
Required if cal_type = “gain”. Array of gains, shape: (Nants_data, Nspws, Nfreqs, Ntimes, Njones), type = complex float.
git_hash_cal
Commit hash of calibration software (from git_origin_cal) used to generate solutions.
git_origin_cal
Origin (on github for e.g) of calibration software. Url and branch.
input_flag_array
Array of input flags, True is flagged. shape: (Nants_data, Nspws, Nfreqs, Ntimes, Njones), type = bool.
observer
Name of observer who calculated solutions in this file.
total_quality_array
Array of qualities of the calibration for entire arrays. The shape depends on cal_type, if the cal_type is “gain” or “unknown”, the shape is: (Nspws, Nfreqs, Ntimes, Njones), if the cal_type is “delay”, the shape is (Nspws, 1, Ntimes, Njones), type = float.

last updated: 2017-07-26