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The UV_PREVIEW command

With large datasets, imaging can be long. [rgb]1,0,0IMAGER offers a simple, fast pre-imaging viewer through command magentaUV_PREVIEW.

This command will display the spectra obtained towards the phase center at several spatial scales (the default is for 4 tapers). It will also attempt to detect spectral features, by analyzing for each spectrum the noise statistics and the outliers. It performs automatic line identifications, using database(s) in the blueLINEDB\ or ASTRO data format selected by command magentaCATALOG. Potential spectral lines in the band are displayed in blue, and detected ones in red. magentaUV_PREVIEW also warns the user about improper scaling of the data weights. The line emission region is indicated in grey.

The result of this automatic signal detection and line identification is saved in a SIC structure named bluePREVIEW%, that is automatically used by commands magentaUV_BASELINE /CHANNELS and magentaUV_FILTER /CHANNELS to respectively remove the continuum and filter the line emission to produce a continuum data set. The detected line frequencies are stored in bluePREVIEW%FOUND%FREQ and their names in bluePREVIEW%FOUND%LINES. This can be used to reference the velocity scale of the data to one of the detected lines, by using command magentaSPECIFY FREQUENCY 'PREVIEW%FOUND%FREQ[1]' for example before further processing.

An example is shown in Fig[*]

Figure: The magentaUV_PREVIEW output
Image preview


next up previous contents index
Next: the SELFCAL SHOW command Up: Specific [rgb]1,0,0IMAGER visualisation tools Previous: Specific [rgb]1,0,0IMAGER visualisation tools   Contents   Index
Gildas manager 2023-06-01