
1 ATMOSPHERE
        [ASTRO\]ATMOSPHERE [INTERPOLATE|MAKE]

    Compute atmospheric  emission,  opacity,  system  temperatures,  etc...,
    using  input  parameters  provided by the user. Input parameters are the
    following SIC variables:
       TEMPERATURE      Outside temperature
       ZERO_PRESSURE    Pressure at sea level.
       AIRMASS          Number of air masses
       WATER            Precipitable water vapor
       FORWARD_EFF      Forward efficiency
       GAIN_IMAGE       Receiver gain ratio
       TREC             Receiver temperature
       FREQ_SIG         Signal frequency (in GHz)
       FREQ_IMA         Image frequency (in GHz)
    These variables  can  be  assigned  using  the  SIC  command  LET.   The
    additional input variables
       ALTITUDE         Site altitude
       FREQ_SIG         Signal frequency (in GHz)
       FREQ_IMA         Image frequency (in GHz)
    are modified by the ASTRO OBSERVATORY and LINE commands.

    The output of the command consists in the following variables
       TRUE_PRESSURE    Local pressure, derived from the site altitude and
                        the sea level pressure by the scale height of 5.5 km.
       TSYS             The system temperature in the signal sideband
       TAU_H2O          The water vapor opacity
       TAU_O2           The dry atmosphere opacity (mostly due to Oxygen,
                        but minor constituents like Ozone may also play a role)
       EMIS_SIG         The atmospheric emission (Kelvin) in the signal sideband
       EMIS_IMA         The atmospheric emission (Kelvin) in the image sideband
       PATH_SIG         The atmospheric excess optical path length (mm)
                        in the signal sideband
       PATH_IMA         The atmospheric excess optical path length (mm)
                        in the image sideband
    These variables can  then  be  used  to  produce  plots  of  atmospheric
    transparency, system temperatures, etc...

    ATMOSPHERE INTERPOLATE
    will do the same calculations,  but  interpolating  the  data  from  the
    binary table (logical name GAG_ATMOSPHERE).

    ATMOSPHERE MAKE filename nf freqmin freqmax
    will create the binary table filename.bin  for  nf  frequencies  between
    freqmin and freqmax (in GHz).

1 CATALOG
        [ASTRO\]CATALOG name [/VELETA] [/ALTERNATE]

    Open the catalog file specified by 'name'.  Default  file  extension  is
    ".SOU".  The  catalog  is  of  the format used at Plateau de Bure.  Some
    standard catalogs are available in the directory GAG_ASTRO :
        SIO.SOU contains SiO masers used for pointing.
        CONTINUUM_1.SOU contains "strong" continuum sources (Flux > 8 Jy)
        CONTINUUM_2.SOU contains weaker sources, still useable for  pointing
        (Flux > 3 Jy).
        PHASE-2000.SOU contains the phase calibrators  of  Plateau  de  Bure
        (Flux > 0.1 Jy)
    The catalog format is described in the ASTRO manual  and  summarized  in
    the subtopic FORMAT".

    /VELETA option will  open  the  catalog  file  'name'.CAT,  assuming  it
    follows  the format of OBSINP catalogs in use on the 30 meter telescope.
    A file 'name'.SOU will be  created  in  the  current  directory  in  the
    Plateau  de  Bure format, so that this option needs to be specified ONLY
    ONCE for each catalog. Fancy options such as  SL0P,  SB0P  ...  are  not
    supported.

    /ALTERNATE option will open the specified catalog as a  second  catalog,
    only  accessible  through  the  "/ALTERNATE" options of commands SOURCE,
    HORIZON, and CONVERT. For instance, a catalog containing calibration  or
    pointing  sources   may  be  opened  as  an Alternate catalog, while the
    objects to  study  are  kept  in  the  Current  catalog,  enabling  easy
    switching between the two kinds of objects.

    CATALOG with no arguments will display the catalogs currently opened.
2 FORMAT
        In the Plateau de Bure format each  source  uses  one  line  of  the
    catalog  file.  Each  line  should  contain  the  following  consecutive
    keywords (some may be omitted):
     1) Source name field:
       The source name field is a composite item which can accomodate several
       names for a single source. Names should be separated by a vertical bar
       ( | ) with no embedded spaces, e.g.: B0415+379|3C111
       Each name must have at most 12 characters.
     2) Coordinate system: 2 characters, optional, may be:
          EQ for equatorial coordinates. If "EQ" is given explicitely,
                                 then the Epoch  keyword is mandatory.
          GA for Galactic II coordinates.
          EC for J2000 Ecliptic coordinates
          HO for horizontal coordinates
          DA for equatorial, present-day coordinates.
     3) Epoch:  needed for equatorial coordinates after "EQ" keyword.
     4) Longitude-like coordinate: in degrees, except for EQ and DA where it
        should be in hours. Format is like hh:mm:ss.sss or dd.ddd or hh:mm.mmm
     5) Latitude-like coordinate: in degrees, same format as above.
     6) Velocity type: alphabetic code , such as "LSR", "HELIO" or "EARTH".
          HELIO actually means: referred to the Solar System barycenter.
     7) Velocity: in km/second, in the corresponding reference frame (LSR,
        HELIOcentric, or EARTH=local). Default is zero.
     8) Intensity type: Either "FLUX" or "MAGNITUDE" (optional)
     9) Intensity: Either the Flux in Jansky or the magnitude (optional)
        The flux can be followed by a spectral index.
1 CONSTEL
        [ASTRO\]CONSTELL [/DRAW [m] [l] [s]] [/NAME] [/BOUNDARIES]

    Plots in the current FRAME with the current FONT, MARKER  and  PEN,  the
    constellations,  i.e.,  the  main stars of all the constellations with a
    marker size adequately depending on the magnitude.  The options are:
     /DRAW [m] [l] [s]
     "m" will cause markers at the star's positions to be plotted
     "l" will cause the constellations outlines to be plotted
     "s" will cause the star's names to be plotted (using current centering and
         character size)
     /NAME will draw the constellation's names
     /BOUNDARIES will draw the constellation boundaries (originally constant RA
         and DEC at 1875 epoch, they are precessed to the current epoch.
         The current code is VERY slow. Use with caution.
    This command makes use of the logical name GAG_CONSTELL which points  to
    a  GILDAS  Table  containing  the stars positions and drawing codes, and
    GAG_CONST_BOUND which defines the constellation boundaries.

1 CONVERT
        [ASTRO\]CONVERT  [Catalog_Name]  [/ALTERNATE]  [/J2000  [Obs_epoch]]
    [/PRECESS  [New_epoch]]  [/GALACTIC] [/FLUX fmin] [/NAME ncname [iname]]
    [/INPUT POS|FLUX filename pos]

    Change catalog format or epoch.

    Without any option (or with option  /ALTERNATE)  and  without  argument,
    this command creates an OBSINP-compatible copy of the 'name'.SOU catalog
    (or Alternate  catalog  if  /ALTERNATE  is  specified)  under  the  name
    'name'.CAT.

    With the /J2000 and/or /PRECESS option, the  command  will  precess  the
    current  SOU  catalog  to  J2000  system, using the specified epochs for
    observation (Obs_epoch,  default  1950)  and  final  result  (New_epoch,
    default  2000).  The  output catalog  is 'Catalog_name'.SOU, and has the
    standard format.

    /FLUX create a copy of the current catalog with  only  sources  of  flux
    larger than fmin

    /NAME ncname [iname]: reserve ncname characters for names  field.   With
    iname.gt.0, a standard name (Jhhmmmsddmmm) is created and put in inameth
    positions in the list of names.

    /INPUT FLUX filename : will take fluxes from filename, which has  itself
    the  format  of  a  catalog (both input catalog and filename are assumed
    alphabetically sorted)

    /INPUT POSITION filename dpos : will take positions  from  filename,  if
    different  by more than dpos arc seconds. Filename has itself the format
    of a catalog (both input catalog and filename are assumed alphabetically
    sorted)

    /ALTERNATE option : do the same operation with the Alternate catalog.
1 FRAME
        [ASTRO\]FRAME System [...]

    This command specifies the reference frame to be used for plots.  System
    may be HORIZONTAL or EQUATORIAL (at epoch defined by TIME command) If no
    other argument is given, plotting is  done  in  rectangular  coordinates
    representing Azimuth Elevation or Right Ascension Declination.  If other
    arguments are given, a Stereographic projection is used.
      - FRAME EQUATORIAL Ra Dec Size
        the projection will be centered on Ra and  Dec  (hours  -  degrees);
        Size in   degrees specify the plotting range
          (ex 180 for a whole hemisphere: the default)
      - FRAME HORIZONTAL Az El Size
        same thing, but Az and El are in degrees.
      - FRAME HORIZONTAL Center
        will plot a hemisphere in horizontal system,  where  Center  may  be
        ZENITH, NORTH, EAST, SOUTH or WEST.

1 HEADER
        [ASTRO\]HEADER

    Write the UTC and LST times on top of plot, as well as  the  observatory
    coordinates.

1 HORIZON
        [ASTRO\]HORIZON h1 h2 ... [/SOURCE ... ] [/PLANET ...  ]  [/AIRMASS]
    [/FLUX Fmin Fmax] [/PROJECT]

    This command is used to produce plots of LST ranges of visibility, above
    specified  elevations,  of  sources and planets. A line is drawn for all
    hours when the object is visible above  elevation  h1;  tick  marks  and
    labels  are  provided  for  elevations  h1,  h2,  ...  (in  degrees), or
    corresponding air masses values (with /AIRMASS option). Elevation values
    must  be in increasing order, or airmasses in decreasing order. UTC axis
    is drawn on  top  of  the  plot.  A  label  with  date  and  observatory
    coordinates is plotted.
        /SOURCE                  will plot on one page all sources
                                 of the Current (by default) or Alternate
                                 (optionally) catalog.
        /SOURCE name1 name2 ...  will be restricted to the specified sources
        /SOURCE NEXT n           will plot the next n sources in the current
                                 catalog; (repeat this command to avoid over-
                                 crowded pages)
        /PLANET                  will plot on one page all solar-system bodies
        /PLANET name1 name2 ...  will be restricted to the specified bodies
        /ALTERNATE               with /SOURCE, will use the Alternate catalog.
        /FLUX Fmin Fmax          restrict the search to sources with flux in
                                 the specified range.
        /PROJECT                 add the project name (for Plateau de Bure
                                 bookkeeping

1 Language
                        ASTRO\ Language summary

    The  ASTRO\  language  contains  commands  to  compute  apparent  source
    positions on the sky at any time(*) for any place on earth.
    ATMOSPHERE          : Compute atmospheric parameters
    CATALOG name        : opens a standard source catalog
    CONVERT             : convert .SOU catalogs to .CAT or J2000 system
    FRAME               : define plotting reference system
    LINE                : plot frequency coverage for Plateau de Bure
    HORIZON             : plot visibility hours of sources and planets
    HEADER              : write time parameters on top of plot
    OBSERVATORY name    : load observatory coordinates
    PLANET [name]       : compute planet coordinates
    SOURCE [name]       : compute source coordinates
    SET parameter value : enter some parameter value
    TIME [time [date]]  : set computation time
    UV_TRACKS           : plot interferometer UV tracks

    * Ephemerides must be available for the planets at this time.
1 LINE
        [ASTRO\]LINE Name Frequency Band [Lock [Center [Harm]]]  [/MOLECULES
    File] [/SPECTRAL Unit Bandwidth IF_2] /WIDTH width
        [ASTRO\]LINE /SPECTRAL Unit Bandwidth IF_2
        [ASTRO\]LINE /AUTO

    Plot rest frequency coverage of Plateau  de  Bure  Interferometer.   The
    command syntax is identical to that of the corresponding command in OBS.
        Name is a line name to label the plot
        Frequency is the center frequency in GHz
        Band should be USB or LSB
        Lock (optional) is LOW or HIGH
        Center (optional), the center IF2 frequency in MHz, default 350.
        Harm (optional), the harmonic number.
    The option /MOLECULES enables to plot the rest  frequencies  of  several
    transitions, found in file File. This is a text file with entries:
        Freq    'chain'
        where Freq is the rest frequency in GHz and 'chain' the line name to
        be plotted by GreG, between single quotes. Example:
        88.632  'HCN'
        89.081  'HCO\u+'
    The option /WIDTH width is used to introduce a finite  width  (in  km/s)
    for the molecular lines displayed.

    The option /SPECTRAL is used to overlay the desired spectral  correlator
    configuration.
        Unit is the correlator unit number (1 to 6)
        Bandwidth is the bandwidth in MHz (10, 20, 40, 80 or 160)
        IF_2 is the center frequency (in MHz) of the unit in the  second  IF
        (in the range 110 to 590 MHz).

    With only the /SPECTRAL option, the corresponding unit overlay  will  be
    drawn on an existing LINE plot.

    Because only one synthesizer is used to generate the 1st  and  2nd  LOs,
    the IF frequency is slightly variable (between 1.500 and 1.550 GHz), and
    the Doppler tracking is correct only for  the  specified  band  (USB  or
    LSB).   The last specified source is used to get the Doppler shift.  The
    image frequency doppler shift is wrong by at most 2.Ers/Harm, where  Ers
    is  the Earth rotation speed, or about 0.9 km/s, roughly 0.04 km/s at 86
    GHz.

    THe option /AUTO is used to guess  the  line  frequencies  and  spectral
    setup for Bure, given a set of variables:

    N_LINE     int  number of line frequencies
    N_CONT     int  number of continuum frequencies
    for each of N_LINE:
    LINENAME_i char line name of line table
    LINEVELO_i char velocity range (2 values: min, max  in km/s)
    LINEFREQ_i dble line frequency (MHz)
    LINEVRES_i dble velocity resolution (km/s)
    for each of N_CONT:
    CONTTABLE_i char  name of continuum  table
    CONTBANDS_i char  range of frequency bands for the continuum
                      (min1 max1 min2 max2 ...)
    Output is also in a set of variables, used by setup writing  procedures.
    look into LINE_* and SPEC_* variables.

1 OBSERVATORY
        [ASTRO\]OBSERVATORY longitude latitude altitude radius
                 or
        [ASTRO\]OBSERVATORY Name

    Specify an  observatory  whose  coordinates  are  known,  or  Enter  the
    observatory geographic coordinates in degrees, and elevation in km above
    sea level. CAUTION: East longitudes are positive.  The  fourth  argument
    is   the  radius  of  the  Sun  avoidance  circle,  in  degrees.   Known
    observatories are  "BURE",  "VELETA",  "LASILLA",  "SEST",  "MAUNA_KEA",
    "JCMT",  "CSO",  "VLA",  "KITT_PEAK",  "EFFELSBERG",  "PARANAL"  (or its
    equivalent "VLT"), "HOPKINS" (or its  equivalent  "IOTA"),and  "PALOMAR"
    (or its equivalent "PTI").

    Example:  OBSERVATORY 44:23:12.0  +45:09:57.9 3.987 30.

    A reasonable  system  default  should  be  introduced  in  command  file
    "GAG_UTIL:ASTRO_LOCAL.ASTRO".  For  known  optical  interferometers, the
    variable FREQUENCY is changed to reasonable values (1.0 to  2.5  microns
    typically).  Use  the command "LET FREQUENCY" to tailor the frequency to
    your needs.

1 PLANET
        [ASTRO\]PLANET [name] [/DRAW [...]]

    Compute the coordinates of a Solar System  object.  Known  objects  are:
    SUN,  MOON,  MERCURY,  VENUS, MARS, JUPITER, SATURN, URANUS, NEPTUNE. By
    default, all known objects are plotted if visible.  The Option /DRAW  is
    used  to  plot  the object symbol on the screen.  The planet coordinates
    (apparent  RA,  apparent  DEC,  Azimuth  and  Elevation   at   time   of
    computation) are typed on the screen.

    PLANET outputs also the geocentric and  heliocentric  distances  of  the
    object  (in A.U.), the apparent minor and major diameters (in arc.sec.),
    the position  angle  of  the  central  meridian  (east  from  north,  in
    degrees), the brightness temperature (in K), and the flux (in Jy) at the
    current frequency. The frequency may be entered either  through  command
    LINE or by updating variable FREQUENCY (in GHz).

    Arguments to /DRAW may be LINE, MARKER, SYMBOL, or FULL:
      LINE   will draw a line from the previously computed position
      MARKER will draw a marker (GreG style defined by GREG\SET MARKER)
              at the computed position
      SYMBOL will draw the planet's symbol at the computed position
      FULL   will combine MARKER and SYMBOL (the symbol will be offset
             one marker size above the computed position).
    If several arguments are given they will be used in sequence.

1 SET
        [ASTRO\]SET parameter value

    Enter a value for a parameter. Valid parameters are :
      - DUT1
        which is (UT1-UTC) in seconds of time (from I.E.R.S.)
      - DTDT
        which is (TDT-UTC) in seconds of time (from I.E.R.S.)
      - AZIMUTH_REFERENCE
        which is either NORTH or SOUTH, and defines the azimuth to  be  zero
        in the North or South direction (to conform to local conventions).
      - FLUX Name Value
        Attribute the flux value Flux to the source Name (only  for  quasars
        or  continuum  sources  which are not planets). This command is used
        when no planet measurement is available and/or as a  redundant  flux
        check  on  strong and well known quasars or W3OH for example. A * as
        flux value frees the source as reference source.
      - SET NAME Argument
        Define the naming convention for listing sources from  the  catalog.
        Sources  in  the catalog may have several names. This command define
        which name  should  be  printed  in  commands  SOURCE  and  HORIZON.
        Argument can be
                names of the source

    Reasonable system defaults may be introduced in  the  command  procedure
    "GAG_UTIL:ASTRO_LOCAL.ASTRO".
1 SOURCE
        [ASTRO\]SOURCE [name [...]] [/DRAW [m]  [l]  [s]  [f]]  [/ALTERNATE]
    [/SUN] [/FLUX Fmin Fmax]

    Compute the coordinates of a Source from the  Current  catalog.   If  no
    name  is  specified,  all  sources  of the catalog are selected.  Source
    coordinates may also be specified in  the  command  line,  in  the  same
    format as the catalog file.  The /DRAW option is used to draw the source
    name on the plot at its  current  position  (Azimuth,  Elevation).   The
    source   coordinates   (RA,  DEC,  Azimuth  and  Elevation  at  time  of
    computation) are printed  on the screen, as well  as  the  line-of-sight
    components of the following velocities:
    increasing.

    Arguments to /DRAW may be LINE, MARKER, SYMBOL, or FULL, as for  command
    PLANET:
      LINE   will draw a line from the previously computed position
             (SOURCE or PLANET)
      MARKER will draw a marker (GreG style defined by GREG\SET MARKER)
             at the computed position
      SYMBOL will draw the source name in capitals at the computed position
      FULL   will combine MARKER and SYMBOL (the name will be offset
             one marker size above the computed position).
    If several arguments are given they will be used in sequence.

    /ALTERNATE will direct the search to the Alternate catalog.

    /SUN will also list the sun avoidance limits

    /FLUX Fmin Fmax will select only sources  with  flux  densities  in  the
    specified  range. Marker sizes will be proportional to the (logarithm of
    the) flux.

    /PRINT option will suppress the printing of Az and  El,  and  print  the
    source characteristics as in catalog instead.

1 TIME
         [ASTRO\]TIME [time [date]] [/ZONE Z] [/UT1] [/TDT] [/NODRAW]

    Specify the time-date of computation. Time is normally understood as UTC
    ;  options  /UT1  and /TDT may be used to change this to UT1 or TDT. The
    time format is HH:MM:SS.SSS, and the date format  is  DD-MMM-YYYY.  Time
    and  date default to current system time.  Local civil time may be input
    instead, in conjunction  with  the  option  /ZONE  z,  where  z  is  the
    difference  in  hours  between  UT  and local civil time (use /ZONE 2 on
    Plateau de Bure in summer, 1 in winter).

    By default, if the sun is visible, a sun avoidance circle is plotted. It
    can be suppressed using the /NODRAW option.

    The radius of the sun avoidance circle is now 30 degrees on  Plateau  de
    Bure.

1 UV_TRACKS
        [ASTRO\]UV_TRACKS station1 station2 [station3 [...]] [/FRAME [size]]
    [/HOUR_ANGLE Hmin [Hmax]] [/TABLE [Name]] [/HORIZON Elmin]

    Plot interferometer UV tracks  for  the  most  recently  called  source.
    Station  coordinates  are  searched  for  in  the  file  ASTRO_STATIONS.
    Stations should be referred to by a mnemonic  (e.g.  E03,  W00  ...).  A
    sketch of the interferometer described by ASTRO_STATIONS is also drawn.
        Option /FRAME 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.
        Option /HORIZON specify a minimum elevation  (in  degrees)  for  the
    source.
        Option /HOUR_ANGLE can be used to limit  the  hour  angle  coverage.
    Default  is  from  source  rise  (above the minimum elevation) to source
    setup. Hmin and Hmax are in decimal hours.
        Option /TABLE can  be  used  to  write  the  sampling  function  (UV
    coverage)  on  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 set.

    The box labelling is in meters. A double labelling in  kilo  wavelengths
    is  drawn if variable FREQUENCY (observing frequency in GHz) is defined.
    Switching to the VLT by the command "OBSERVATORY VLT" defines  FREQUENCY
    to  some  1  micron  (300  THz). Some labellings are then in wavelengths
    (microns).  Switching between files describing  interferometer  stations
    can be done inside ASTRO by redefing 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:astro_stations.dat)
    The VLT stations are described in  the  file  ephemeris/vlt_stations.dat
    (and accessed by
    SIC LOG ASTRO_STATIONS GAG_ASTRO:vlt_stations.dat)
    The IOTA stations are described in the file  ephemeris/iota_stations.dat
    (and accessed by
    SIC LOG ASTRO_STATIONS GAG_ASTRO:iota_stations.dat)
    The PTI stations are described in  the  file  ephemeris/pti_stations.dat
    (and accessed by
    SIC LOG ASTRO_STATIONS GAG_ASTRO:pti_stations.dat)
1 END






