Configuring PolyFiX with ASTRO for PMS

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Configuring PolyFiX with ASTRO for PMS

The software ASTRO should be used to set up the receiver and correlator configuration. A description of the PolyFiX correlator and of the commands provided in ASTRO to prepare the correlator configuration can be found in this PolyFiX tutorial. Please use the latest version of GILDAS.

The essential ASTRO commands are:

- TUNING: receiver tuning
- BASEBAND: selection of baseband(s)
- SPW: selection of chunks to define high resolution spectral windows
- PROPOSAL: exports a script that needs to be uploaded to PMS

Receiver tuning is done on a fixed grid of LO frequencies, spaced by 500 MHz throughout each receiver band, on which the receiver performance is optimized. For a correct receiver tuning, either the source LSR velocity or the redshift is needed, or the (red)shifted frequencies should be used directly. In the latter case, the LSR velocity (or redshift) has to be set to zero in the source command. Also, the frequencies of molecular lines from the standard line catalogue in ASTRO that can be plotted over the spectrum (by setting set lines on in ASTRO) have to be redshifted by hand, i.e., a revised molecular catalogue needs to be uploaded in ASTRO (with catalogue myfile.lin /LINE). For more details see the internal help for the different ASTRO commands and this PolyFiX tutorial.
A typical session in ASTRO would be:

       ! Define a source with LSR velocity
       SOURCE TOTO EQ 2000 09:11:39.786 -
                           30:53:29.257 LSR 7.0

       ! choice of receiver tuning
       TUNING 232.686 LSB 7500
       ! ASTRO will shift the IF centering by
       ! 180.6MHz to match the tuning grid

       TUNING 232.686 LSB 7319.4 /ZOOM
       ! Plots the selected receiver band only

       BASEBAND
       ! select all 8 basebands

       ! define and display high resolution
       ! spectral windows (central frequency
       ! and width specified)
       SPW /FREQUENCY 244.9 0.2
       SPW /FREQUENCY 245.6 0.2
       SPW /FREQUENCY 232.686 0.03
       SPW /FREQUENCY 230.538 0.08
       SPW /FREQUENCY 231.15 0.3
       ...
       PROPOSAL /FILE MyFile.astro
       ! write the series of commands
       ! to set up the instrument;
       ! THE MyFile.astro NEEDS TO BE
       ! UPLOADED TO PMS

The TUNING command produces a plot showing the full 15.488 GHz bandwidth covered with both sidebands. The TUNING command checks that the LO frequency is located on the 500 MHz-spaced tuning grid. If this is not the case, the command moves the tuned frequency to a neighboring IF center frequency that matches the grid. The option /FIXED_FREQ can be used to ignore the tuning grid (e.g., if using the tuning grid does not cover all desired lines with the proposed tuning or if a contiguous spectral scan is requested).

PMS will only accept to load ASTRO scripts created with the PROPOSAL command (which uses the NOEMA OFFLINE syntax). This will allow PMS to show spectral coverages in a consistent way for any kind of projects (including line markers at the correct rest frequency for redshifted sources for instance).

Old NOEMA ONLINE language scripts, i.e. those created by the SETUP command (e.g., from the W17 semester) can be converted by typing in ASTRO:

    OBSERVATORY NOEMA ONLINE
    @ MyOnLineScript.astro
    PROPOSAL /FILE MyOfflineScript.astro