listobs task: List the summary of a data set in the logger or in a file

List the summary information of a data set in the logger or in a file, based on a data selection. Only rows can be selected and printed. No in-row selection is possible (channel or correlation). Refer to the task listvis to list visibilites.

Lists the following properties of a MeasurementSet: scan list, field list, spectral window list with correlators, antenna locations, MS table information.

Note: The 'Int (s)' column is the average of the MS's INTERVAL column for each scan. So in a time-averaged MS, 'Int' = 9.83s probably means five 10-second integrations and one 9-second integration (timebin) rather than six 9.83-second integrations.

Description of algorithm to calculate the number of unflagged rows

The number of unflagged rows is only computed if listunfl=True. Computing these quantities can have a negative performance impact, especially for large datasets. The number of unflagged rows (the nUnflRows columns in the scans and fields portions of the listing) is calculated by summing the fractional unflagged bandwidth for each row (and hence why the number of unflagged rows, in general, is not an integer). Thus a row which has half of its total bandwidth flagged contributes 0.5 rows to the unflagged row count. A row with 20 of 32 channels of homogeneous width contributes 20/32 = 0.625 rows to the unflagged row count. A row with a value of False in the FLAG_ROW column is not counted in the number of unflagged rows.