SkyModel Parameters

These are the standard attributes of SkyModel objects.

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

Angle type attributes also have convenience properties named the same thing with ‘_degrees’ appended through which you can get or set the value in degrees.

Similarly location type attributes (which are given in topocentric xyz coordinates) have convenience properties named the same thing with ‘_lat_lon_alt’ and ‘_lat_lon_alt_degrees’ appended through which you can get or set the values using latitude, longitude and altitude values in radians or degrees and meters.

Required

These parameters are required to have a sensible SkyModel object and are required for most kinds of catalog files.

Ncomponents

Number of components

Nfreqs

Number of frequencies if spectral_type is ‘full’ or ‘subband’, 1 otherwise.

coherency_radec

Ra/Dec coherency per component

component_type

Type of component, options are: ‘healpix’, ‘point’. If component_type is ‘healpix’, the components are the pixels in a HEALPix map in units compatible with K or Jy/sr. If the component_type is ‘point’, the components are point-like sources in units compatible with Jy or K sr. Determines which parameters are required.

dec

Declination of components in ICRS coordinates.

history

String of history.

name

Component name, not required for HEALPix maps.

ra

Right ascension of components in ICRS coordinates.

spectral_type

Type of spectral flux specification, options are: ‘full’,’flat’, ‘subband’, ‘spectral_index’.

stokes

Component flux per frequency and Stokes parameter

Optional

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

above_horizon

Boolean indicator of whether this source is above the horizon at the current time and location. True indicates the source is above the horizon.

alt_az

Altitude and Azimuth of components in local coordinates.

beam_amp

Beam amplitude at the source position as a function of instrument polarization and frequency.

extended_model_group

Identifier that groups components of an extended source model. Set to an empty string for point sources.

freq_array

Frequency array in Hz, only required if spectral_type is ‘full’ or ‘subband’.

hpx_inds

Healpix index, only reqired for HEALPix maps.

nside

Healpix nside, only required for HEALPix maps.

pos_lmn

Position cosines of components in local coordinates.

reference_frequency

Reference frequency in Hz, only required if spectral_type is ‘spectral_index’.

spectral_index

Spectral indexm only required if spectral_type is ‘spectral_index’.

telescope_location

Telescope Location for local position calculations.

time

Time for local position calculations.

last updated: 2021-02-17