UVFlag Parameters¶
These are the standard attributes of UVFlag objects.
Under the hood they are actually properties based on UVParameter objects.
Required¶
These parameters are required to have a sensible UVFlag object and are required for most kinds of uv data files.
- Nants_data
Number of antennas with data present. Only available for “baseline” or “antenna” type objects.May be smaller than the number of antennas in the array
- Nants_telescope
Number of antennas in the array. Only available for “baseline” type objects. May be larger than the number of antennas with data.
- Nbls
Number of baselines. Only Required for “baseline” type objects.
- Nblts
Number of baseline-times (i.e. number of spectra). Not necessarily equal to Nbls * Ntimes
- Nfreqs
Number of frequency channels
- Npols
Number of polarizations
- Nspws
Number of spectral windows (ie non-contiguous spectral chunks). More than one spectral window is not currently supported.
- Ntimes
Number of times
- ant_1_array
Array of first antenna indices, shape (Nblts). Only available for “baseline” type objects. type = int, 0 indexed
- ant_2_array
Array of second antenna indices, shape (Nblts). Only available for “baseline” type objects. type = int, 0 indexed
- baseline_array
Array of baseline indices, shape (Nblts). Only available for “baseline” type objects. type = int; baseline = 2048 * (ant1+1) + (ant2+1) + 2^16
- freq_array
Array of frequencies, center of the channel, shape (Nspws, Nfreqs), units Hz
- history
String of history, units English
- label
String used for labeling the object (e.g. ‘FM’). Default is empty string.
- lst_array
Array of lsts, center of integration, shape (Nblts), units radians
- metric_array
Floating point metric information, only availble in metric mode. shape (Nblts, Nspws, Nfreq, Npols).
- mode
The mode determines whether the object has a floating point metric_array or a boolean flag_array. Options: {“metric”, “flag”}. Default is “metric”.
- polarization_array
Array of polarization integers, shape (Npols). AIPS Memo 117 says: pseudo-stokes 1:4 (pI, pQ, pU, pV); circular -1:-4 (RR, LL, RL, LR); linear -5:-8 (XX, YY, XY, YX). NOTE: AIPS Memo 117 actually calls the pseudo-Stokes polarizations “Stokes”, but this is inaccurate as visibilities cannot be in true Stokes polarizations for physical antennas. We adopt the term pseudo-Stokes to refer to linear combinations of instrumental visibility polarizations (e.g. pI = xx + yy).
- time_array
Array of times, center of integration, shape (Nblts), units Julian Date
- type
The type of object defines the form of some arrays and also how metrics/flags are combined. Accepted types:”waterfall”, “baseline”, “antenna”
- weights_array
Floating point weight information, shape (Nblts, Nspws, Nfreq, Npols).
Optional¶
These parameters are defined by one or more type but are not always required. Some of them are required depending on the type (as noted below).
- ant_array
Array of antenna numbers, shape (Nants_data), Only available for “antenna” type objects. type = int, 0 indexed
- extra_keywords
Any user supplied extra keywords, type=dict.Use the special key ‘comment’ for long multi-line string comments.Default is an empty dictionary.
- flag_array
Boolean flag, True is flagged, only availble in flag mode. shape (Nblts, Nspws, Nfreq, Npols).
- weights_square_array
Floating point weight information about sum of squares of weights when weighted data converted from baseline to waterfall mode.
- x_orientation
Orientation of the physical dipole corresponding to what is labelled as the x polarization. Options are “east” (indicating east/west orientation) and “north” (indicating north/south orientation)
last updated: 2021-07-21