task description

Task importnro enables one to convert the data obtained with the NRO45m telescope into the CASA MS2 format. Usage of this task is very simple. Set infile and outputvis, then run the task. At this moment, only the OTF data (NOSTAR data) obtained with the SAM45 spectrometer is supported, and the OTF data obtained with the other spectrometers (e.g., AOS) and the PSW data (NEWSTAR data) are outside of scope (Jan./25/2017)

An important point in using importnro is the treatment of the beams of the multi-beam receiver such as FOREST, where different beams are assigned to different antennas (not beam!). When using other tasks such as plotms or sdbaseline, individual beams can be specified in the following ways:

(When you specify beam 1,)
antenna = ‘0&&&’,
antenna = ‘0&&0’, or
antenna = ‘NRO-BEAM0’.

Another important point is about the array of SAM45. Except for FOREST, importnro assigns SAM45’s sixteen arrays labelled A01-A16 to spw of 0-15 in ascending order, even if some different arrays share the same frequency setting. As a result, every MS2 file generated via importnro has sixteen spw IDs due to the high flexibility of the frequency setting in SAM45.

On the other hand, in the data obtained using FOREST, assignments of four beams, two polarizations, and two sidebands (4 x 2 x 2 = 16) to SAM45’s sixteen arrays are fixed, and there is no flexibility for users in choosing arrays when preparing the observation tables. Hence importnro generates a MS2 file which contains only two spw IDs (0 and 1) when importing FOREST OTF data. This is also the case in the so-called spectral window mode of FOREST, which enables one to use thirty-two arrays and to set four frequency settings. In this case importnro returns a MS2 file having four spw IDs (0-3).

The other parameters can be specified in the same manner as in the ALMA data. The results of the data import can be checked using task listobs.