"Scan intent'' Based Selection

"Scan intent" selection is based on the entries in the "OBS_MODE" column of the "STATE" sub-table. The main table of a Measurement Set has the "STATE_ID" column containing the row number of the "STATE" sub-table appropriate for each row in the main table. The "OBS_MODE" column of the STATE sub-table contains strings describing the observational intent. These intents are referred to as "scan intents" and the scan-intent expressions in the MSSelection module can be used for data selection based on these intents.

Syntax

The scan-intent selection expression is a comma-separated list of specifications. Each specification can be a string, an integer or an integer range. As in other such expressions, a range $[N0,N1]$ can be specified as N0$\sim$ N1 (see Section 1.2). Strings can be regular expressions or patterns or quoted-strings for as-is matching (see Section 1.4).

A single scan can have multiple scan-intents represented by a comma-separated list of strings like "CALIBRATE_BANDPASS.UNSPECIFIED,CALIBRATE_AMPLI.UNSPECIFIED". Each of these comma-separated components are referred to as the scan-intent components. All string specifications in scan-intent expression are matched against each of these comma-separated components. Scans with any of the scan-intent components matching the string(s) in the scan-intent expression are selected. E.g. scanintent=*CAL*, *BAND* will select all scans which have the strings "CAL" or "BAND".

To allow selection based on scan-intent components, scan-intent selection specifications can also be ampersand-separated ('&') list strings. Only those scans, at least one scan-intent components of which match all the ampersand-separated components are selected. E.g. scanintent=*CAL* & *BAND* will select only those scans the intent strings of which contain the strings "CAL" and "BAND". See Section 8.2 for more examples.

Table 2: Example scan-intent table

Scan No.	Scan-intent strings
0	CALIBRATE_BANDPASS, CALIBRATE_PHASE
1	CALIBRATE_BANDPASS, CALIBRATE_AMPLI
2	CALIBRATE_BANDPASS, CALIBRATE_AMPLI, CALIBRATE_PHASE
3	AMPLI_UNSPECIFIED, PHASE_UNSPECIFIED

Examples

Table 2 shows an example-table of scan-intents. Table 3 shows a list of some scan-intent selection expressions and the corresponding list of selected scan numbers from Table 3.

Table 3: Example of scan-intent selection expressions for scan-intents in Table 2

Scan-intent	Selected	Remarks
selection expression	scans
CALI*	0,1,2
*PHASE	0,2	Matches
		CALIBRATE_PHASE but
		not PHASE_UNSPECIFIED
*UNSPEC*	3
*AMPLI, *PHASE	1,2	*AMPLI matches
		CALIBRATE_AMPLI;
		*PHASE matches
		CALIBRATE_PHASE
*AMP*	1,2,3	*AMP* matches
		CALIBRATE_AMPLI and
		AMPLI_UNSPECIFIED
*BAND & *PHASE	0,2	*BAND and *PHASE are
		simultaneous present
		for scans 0 and 2 only
AMP* & *PHASE*	3	*PHASE* matches scans
		0,2,3. AMP* matches
		only scan 3.
*BAND & *PHASE* & *AMP*	2	Only scan that matches
		*BAND and
		*PHASE* and *AMP* is
		scan 2
*BAND & *PHASE*, AMPLI*	0,2,3	*BAND & *PHASE
		selects scans 0,2.
		AMPLI* selects scan 3