UV Distance Selection

Syntax

A uv-distance specification is given as a physical quantity (number with units in the format N[UNIT] where UNIT is optional). This is referred to as UVDIST in the description below. Units are optional with the default unit being meter. Units can be specified as "m"/"M" (for Mega) or "k"/"K" (for Kilo) followed by "m"/"M" (for meter) or "lambda"/"LAMBDA" (for wavelength). User supplied values are converted to internal Measurement Set units using the spectral window sensitive reference frequency.

If only a single UVDIST is specified, all rows that exactly match the given UVDIST are selected. When UVDIST is given as a range in the format N0$\sim$ N1[UNIT] (where N0 and N1 are valid numbers), all rows corresponding to the uv-distance between N0 and N1 (N0 and N1 included) are selected.

Rows can also be selected via boolean expressions. When specified in the format "$>$ UVDIST", all rows with uv-distance greater than the given uv-distance (converted to the appropriate units) are selected. When specified in the format "$<$ UVDIST", all rows with uv-distance less than the given uv-distance (converted to the appropriate units) are selected.

To selected rows with uv-distance within an equal range on either side of a given value, UVDIST can be specified as a percentage of the given value in the format N%. All rows with uv-distance between +/-N percent of the given uv-distance in appropriate units are selected.

The full uv-distance selection expression is a comma-separated list of any of the above mentioned uv-distance specifications. E.g.

• uvdist=100Klambda selects all baselines for which $\sqrt{u^2+v^2}$ is equal to 100 K$\lambda$ .
• uvdist=100Km selects all baselines for which $\sqrt{u^2+v^2}$ is equal to 100 Km.
• uvdist=100$\sim$ 200Klambda selects all baselines for which $\sqrt{u^2+v^2}$ is in the range [100, 200] K$\lambda$ .
• uvdist=$>$ 100Klambda selects all baselines for which $\sqrt{u^2+v^2}$ is greater than 100 K$\lambda$ .
• uvdist=$<$ 100Klambda selects all baselines for which $\sqrt{u^2+v^2}$ is less than 100 K$\lambda$ .