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1.3 ms - Module

Module for measurement set operations

  1.3.1 ms - Tool
    ms.ms - Function
    ms.fromfits - Function
    ms.fromfitsidi - Function
    ms.listfits - Function
    ms.createmultims - Function
    ms.ismultims - Function
    ms.getreferencedtables - Function
    ms.getfielddirmeas - Function
    ms.nrow - Function
    ms.nrow2 - Function
    ms.iswritable - Function
    ms.open - Function
    ms.reset - Function
    ms.close - Function
    ms.name - Function
    ms.statwt2 - Function
    ms.tofits - Function
    ms.summary - Function
    ms.getscansummary - Function
    ms.getspectralwindowinfo - Function
    ms.listhistory - Function
    ms.writehistory - Function

Description A CASA measurement set is a CASA table which obeys specific conventions. These conventions are defined in note 229. Like all CASA tables the measurement set will always appear as a directory which contains a number of files and directories.

Measurement set tables come in two slightly different versions, single dish and interferometric. Single dish measurement sets store the observed data as real numbers in the FLOAT_DATA column of the measurement set, whereas interferometric ones use complex numbers in the DATA column.

A measurement set table can contain data from a variety of different observations with different spectral or polarimetric configurations, different pointings and different instruments. To do this it needs to handle data with differing shapes. The data shape referred to here is two-dimensional with the length of the axes being the number of correlations and the number of channels in the data. A typical shape might be [4, 1], which could correspond to a continuum observation where the [RR, LL, RL, LR] polarizations where correlated. In the same measurement set there may be data with a shape of [1, 32], which corresponds to a spectral line observation, with 32 channels, where only the [XX] polarizations are correlated.