Description of baseline selection parameters

Names of baselines to be matched. It can be given as either a vector of vectors or as a casacore MSSelection string. These two methods are mutually exclusive. When in doubt, use the second syntax.

Syntax 1: vector of vectors

If given as a vector, a vector element can be a vector of two names giving the stations forming a baseline :

  1. baseline=[ [CS001,RS003], [CS002,RS005] ] selects baselines CS001-RS003 and CS002-RS005.

Each name can be a shell-type pattern (with wildcards * ? [] or {}) :

2. baseline=[ [CS*,RS*], [CS*,CS*], [RS*,RS*] ] or baseline=[ {CS*,RS*},{CS*,RS*} ] selects all baselines (also autocorrelations) between core and remote stations.

Note that the wildcard characters {} mean OR. They can be used to pair groups of stations (quotes are needed) :

  1. baseline=[ ["{CS001,CS002}","{RS003,RS005}"] ] selects baselines CS001-RS003, CS001-RS005, CS002-RS003, and CS002-RS005.

Besides giving a baseline, it is also possible to give a single station name (possibly wildcarded) meaning that only baselines containing that station will be selected.

It is a bit hard to select international stations using this syntax.

Syntax 2: casacore baseline selection

This syntax is also described in this note and Casacore note 263. The advantage of this syntax is that it is more concise and that besides a station name pattern, it is possible to give a station number. The examples above can be expressed as :

  1. baseline=CS001&RS003;CS002&RS005 for baselines CS001-RS003 and CS002-RS005.

  2. baseline=[CR]S*&& for baselines (also autocorrelations) between RS and CS stations (i.e. discard all baselines involving international stations).

  3. baseline=CS001,CS002&RS003,RS005 for CS001-RS003, CS001-RS005, CS002-RS003, and CS002-RS005

Note that & means cross-correlations, && means cross and auto, &&& means auto only. If there is nothing to the right of the ampersand(s), it means the right bit will be equal to the left bit. Therefore, baseline=CS*&& selects the same as baseline=CS*&&CS* which selects all cross and auto-correlations of the core stations.

International stations can be selected most easily using negation :

  1. baseline=^[CR]S*&&* to select all baselines containing at least one international station; read this as “Cross and autocorrelations between (not core or remote stations) and any other station”.

  2. baseline=^[CR]S*&& to select baselines containing ONLY international stations; read this as “Cross and autocorrelations between (not core or remote station) and (not core or remote station)”.

Sometimes the baselines between the HBA ears of the same station should be deselected :

  1. ^/(.*)HBA0&\1HBA1/ (the \1 is back substitution for the (.*) on the left). Without the caret only such baselines are selected.

Note`:` in the msin step only the baseline selection syntax is possible. Also note that, currently, only the first way works properly when selecting baselines after a station has been added. The reason is that the second way looks in the original ANTENNA table to find matching station names, thus will not find the new station . Parameters to select on baseline can be used in the steps preflagger and filter. The step msin.baseline only supports syntax variant 2.

Filtering out some stations

  1. baseline=!CS401HBA0,CS401HBA1,RS205HBA filters out all baselines involving CS401HBA0, CS401HBA1 or RS205HBA.

Full examples

Say we have a measurement set containing CS001HBA0, CS001HBA1, RS307HBA, IT509HBA. Then the following examples yield the given baselines:

  1. baseline=[CR]S*&&: keeps all baselines (also autocorrelations) with CS001HBA0, CS001HBA1, RS307HBA. So discard international stations.

  2. baseline=^CS001HBA0,RS307HBA&&: keeps all baselines (also autocorrelations) with CS001HBA1 and IT509HBA. So discard CS001HBA0 and RS307HBA.

If you want to debug your baseline selection syntax, you can query the baselines in a measurement set with taql select distinct mscal.ant1name(), mscal.ant2name() from bla.MS








Correlation type to match? Must be auto, cross, or an empty string (= all) .







See above .







Zero or more ranges of physical baseline lengths (in m). A baseline matches if its length is within one of the ranges. E.g., blrange=[0,10000, 100000, 1e30] matches baselines shorter than 10km and baselines longer than 100km .