[ASTRO\]UV_TRACKS station1 station2 [station3 [...]] [/FRAME [size]] [/HOUR_ANGLE Hmin [Hmax]] [/TABLE [Name]] [/HORIZON Elmin] [/IN- TEGRATION t] [/STATIONS ALL|list] [/WEIGHT Mode] Plot interferometer UV tracks as observed with the Plateau de Bure in- terferometer (but the command is in fact more general and can be used with any array). Station coordinates are searched for in the file defined by the AS- TRO_STATIONS logical variable. Stations should be referred to by a mnemonic (e.g. E03, W00 ...) given as arguments of UV_TRACKS. The coordinates of the most recently selected SOURCE or PLANET are con- sidered. Option /HORIZON specifies a minimum elevation (in degrees) for the source. Option /HOUR_ANGLE can be used to limit the hour angle cov- erage. Default is from source rise (above the minimum elevation) to source setup; Hmin and Hmax are in hours. The frequency of the simulat- ed observation is read in the FREQUENCY SIC variable (which is also used by several other commands in ASTRO). UV_TRACKS can be used iteratively, to simulate the observations of sev- eral configurations. Option /FRAME [size] should be used to start a new UV coverage. It clears the plot, draws the box, and open a new table if /TABLE is present. 'size' is the maximum UV spacing plotted, in meters (default 800 m). Subsequent call to the command (without /FRAME) adds the new configurations. The user may select another color pen to dis- tringuish between the various coverages. A sketch of the interferometer described by ASTRO_STATIONS is also drawn, and the selected stations/an- tennas are highlighted. Option /TABLE can be used to write the sampling function (UV coverage) in a UV table for further processing such as producing beams using the task UV_MAP. Name should be specified only if option /FRAME has been used, to initialize the table. Subsequent call to the UV_TRACK command will append the new observation to this table. The visibilities written in the UV table are constant, as if a point source were observed (real part = 1, imaginary part = 0). The weight is by default constant, equal to 1. This can be modified using the /WEIGHT Mode option. Mode can be UNIFORM (constant weight) or AIRMASS (weight proportional to airmass^-2, i.e. to sin(elevation)^2). Option /INTEGRATION t [min] is used to change the time interval between points in the UV plane (currently there is a max of 3000 points between HA_MIN and HA_MAX). Default is 15 minutes per point. ---- Notes for experts ---- Option /STATIONS enable to access stations by their rank number in the ASTRO_STATIONS file, rather by their mnemonic. ALL means 'take all sta- tions'. Switching between files describing interferometer stations can be done inside ASTRO by redefining the ASTRO_STATIONS logical variable using the command SIC LOG ASTRO_STATIONS "path/to/the/desired/file" The BURE stations are described in the file ephemeris/astro_stations.dat (and accessed by default on most ASTRO installs, or otherwise by SIC LOG ASTRO_STATIONS GAG_ASTRO_DATA:astro_stations.dat)