
1 ACCUMULATE
        LAS\ACCUMULATE

    ACCUMULATE is used to integrate step by step  an  ensemble  of  spectra.
    The  T  spectrum is added to the spectrum in R with the current weights.
    R thus contains the current sum, and T the last  sum.  As  command  SUM,
    ACCUMULATE   checks  for  the  positional  coincidence  and  calibration
    homogeneity according to SET MATCH  and  SET  CALIBRATION  respectively.
    Alignement of spectra is checked according to SET ALIGN command.

    For EQUAL weights, ACCUMULATE computes  the  SUM  of  the  two  spectra,
    allowing  addition of an ensemble of spectra after division by the total
    number of spectra.

    ACCUMULATE also works on Continuum drift. The alignement may be  Channel
    or Position in this case.

1 BASE
        LAS\BASE [Deg] [/PLOT] [/CONTINUUM [flux]]
        LAS\BASE SINUS Amplitude Period Phase [/PLOT]
        LAS\BASE LAST [/PLOT]

    BASE copies R into T, then subtracts from R  a  polynomial  baseline  of
    degree  Deg, or a sinusoidal baseline if the first argument is SINUS. In
    the latter case, SINUS must be followed by  the  Amplitude,  Period  and
    Phase  (in  the same unit as the period, usually km/s or MHz) of a trial
    sinusoid. Minimization will be done including also a linear baseline  in
    addition  to  the  sinusoid. Zones defined by the SET WINDOW command are
    not used to fit the baseline.
             BASE LAST will use the  last  determined  baseline  instead  of
    computing  a  new  one.  It  can  be  useful to find a baseline from one
    backend and apply it  to  another.  This  also  applies  for  sinusoidal
    baselines.
             /PLOT  plots this baseline after the minimization.

    BASE /CONTINUUM will divide the spectrum by  the  baseline  rather  than
    substracting  it.  This  is  useful  to  keep  the continuum level, when
    continuum is present and variations of atmospheric emission are properly
    substracted  out  by  fast enough switching.  This is of course the case
    for correlation  spectra  (e.g.  coming  from  an  interferometer).  The
    continuum level will be adjusted to the value of the argument `flux', if
    present; e.g.  /CONTINUUM  1.0  will  produce  a  spectrum  of  line-to-
    continuum  ratio.  BASE  /CONTINUUM does not work with BASE LAST or BASE
    SINUS.

    For On-The-Fly scans, BASE subtracts a basline  on  all  the  individual
    spectra.
1 BOX
        LAS\BOX [Arg1] [Arg2] [Arg3] [Arg4] [/UNIT Type [UPPER]]

    BOX draws a frame for the spectra; the units and limits  are  determined
    according  to  the options of the SET command (SET MODE ; SET UNIT), and
    the box size governed by SET BOX.

    The first two arguments are used to modify the labelling  of  the  lower
    and  left  axes  respectively.  They  may take the values P for parallel
    labels (default for X axis), O for  Orthogonal  labels  (default  for  Y
    axis) or N for No labels. A third argument is available to indicate that
    the ticks are to be In or Out  of  the  box.  The  fourth  argument,  if
    present  indicates  for  which  axis  labels should be plotted. Possible
    values are X, Y and None.
             If the option /UNIT is present, it modifies (with no  permanent
    action) the units of the X axis, or only of the upper X axis if UPPER is
    specified. Type may be  also  IMAGE  to  get  image-side-band  frequency
    units. For Continuum data, the /UNIT command has no effect, but the unit
    is controlled by the SET ANGLE command.

1 CALIBRATE
        LAS\CALIBRATE [KEY val] [KEY val] ...

    This command show the calibration parameters if given without arguments.
    Called  with  a  list  of  arguments  in the form "KEY value", where KEY
    stands  for  BEAM_EFF,  FORWARD_EFF,  GAIN_IMAGE,  H2O,  P_AMB,   T_AMB,
    T_CHOPPER   or  T_COLD,  and  value  is  the  corresponding  value  for,
    respectively, a (new) Beam efficiency, Forward efficiency,  Image/Signal
    gain  ratio,  mm of water vapor, ambient temperature, hot load (chopper)
    temperature, cold load  temperature,  will  recompute  the  calibration,
    update the header and rescale the spectrum accordingly.

1 DROP
        LAS\DROP Obs [Ver]

    Remove an Observation from the current index. The version number must be
    specified  if  it  is  not the last in the input file, even if it is the
    last version in the current index.

1 DUMP
        LAS\DUMP [Argument]

    A debugging command no longer used very much.  Without an  argument,  it
    lists a certain number of informations about the R Observation header (A
    CERTAIN number doesnot mean ALL, although it should...).  With  "D[ATA]"
    as  argument,  it  lists  in addition the data values.  With "F[ILE]" as
    argument, it lists information about the  input  and  output  file,  and
    finally with "I[NDEX]", it lists information about the current index.

1 FILE
        LAS\FILE Type Name [NEW]

    Selects the input and output files.
    FILE IN name            defines the input file
    FILE OUT name [NEW]     defines the output file ;
                            initializes a file if NEW is precised.
    FILE BOTH name          selects the same file for input and output.
    The default extension can be specified using command SET EXTENSION (.BUR
    is recommended).

1 FIND
        LAS\FIND [Append] [New_Data] [/ALL] [/LINE Lname]  [/NUMBER  n1  n2]
    [/OFFSET  o1  o2]  [/SCAN  s1  s2] [QUALITY q] [/RANGE w e s n] [/SOURCE
    Sname] [/TELESCOPE Tname]

    FIND performs a search in the input file to build a new index, according
    to  selection criteria defined by the SET command. These criteria may be
    temporarily modified by the following options:
    /ALL             all versions of each scan are searched for
                     (if not present: only the last version)
    /LINE Lname      search by line name
    /NUMBER n1 n2    search for the specified range of observation numbers
    /SCAN s1 s2      search for the specified range of scan numbers
    /OFFSET a1 a2    search for these offsets
    /QUALITY q       search for the data of quality better than Q
    /RANGE w e s n   search for the specified range of offsets
    /SOURCE Sname    search by source name
    /TELESCOPE Tname search for the telescope used
    FIND by default overwrites the current index. Found observations may  be
    appended  to  the  current  index by specifying the argument APPEND ; an
    index compression occurs to avoid duplication of scans in the index.

    FIND does not return an error if the index is empty,  but  the  variable
    FOUND  is set to 0. FOUND is always set to the number of observations in
    the index.

    Argument NEW_DATA can be used to wait until new data is present  in  the
    input   file.   This  possibility  is  intended  for  sites  where  data
    acquisition is done in CLASS format (Pico Veleta, Plateau  de  Bure)  to
    use  CLASS as an automated quick look facility. The behaviour is similar
    to that of command NEW_DATA, but all selection criteria  are  considered
    and no switching to a new observation type occurs.
1 FOLD
        LAS\FOLD

    Folds frequency-switched spectra.

1 GET
        LAS\GET [N]

    GET copies R into T, and loads the  Observation  number  N  in  R.   The
    current  index  initialized  by FIND is first explored, then, if needed,
    the whole  input  file.  If  N  is  absent,  the  previous  (last  read)
    Observation  is  recovered.  If N is FIRST, the first Observation of the
    current index is loaded. If N is  NEXT,  the  next  Observation  in  the
    current index is loaded.

1 HEADER
        LAS\HEADER

    Displays some header information on the R Observation.  The FULL  format
    is  used,  with the informations selected in command SET FORMAT written.
    The lines written contain (in  output  order,  but  not  all  lines  are
    necessarily present)
      - General information line:
        Scan number and version
        Source name
        Line name
        Telescope name
        Date of observation
        Date of last reduction
      - Position information line
        RA or l: right ascension or longitude (or azimuth)
        DEC or b: declination or latitude (or elevation)
        Epoch if equatorial coordinates are used
        Offsets in current units
        Type of coordinate (Eq, Ga, Az)
      - Quality information line:
        Quality of calibration (as defined by a SET QUALITY)
        Tau: opacity at zenith
        Tsys: system temperature (outside atmosphere).
        Time: total integration time on source (minutes)
        El: elevation of source
      - Spectral information lines (2):
        N: number of channel
        I0: reference channel (real)
        V0: velocity at reference channel
        Dv: velocity resolution (signed)
        F0: rest frequency at reference channel
        Df: frequency resolution (signed)
        Fi: image frequency at reference channel
      - Calibration information line:
        B_ef : Beam efficiency of telescope
        F_ef : Forward efficiency of telescope
        G_im : Gain in image band
      - Atmospheric information lines (2):
        H2O : millimeter of precipitable water vapor
        Pamb: ambient pressure
        Tamb: ambient (receiver cabin) temperature
        Tchop: Chopper temperature
        Tcold: Cold load temperature
        Tatm: Atmospheric temperature in the signal band
        Tau: Zenith opacity in the signal band
        Tatm_i: Atmospheric temperature in the image band
        Tau_i: Zenith opacity in the signal band
      - Continuum Drift information lines (2) :
        N: Number of points
        I0: Reference point
        A0: Angle offset at reference point
        Da: Angular spacing between points (signed).
        F0: Observing frequency
        Df: Band pass
        Pos. Ang. : Position angle of the drift.
    followed by the list of Scan numbers added in the observation.

1 IGNORE
        LAS\IGNORE List_of_Observations

    This command can be used to declared the specified list of  Observations
    (from  the  INPUT  file)  to  be  ignored  in  all FIND operations. They
    effectively become invisible to CLASS (except in  a  LIST  IN  command),
    until a FILE IN command is typed again. The input file is not physically
    modified however. The list of observation may have the  same  format  as
    the index list of a FOR command.

1 Language
        LAS\ Command Language Summary
    ACCUMULATE      : Add R and T observation.
    BASE [arg]      : Subtract a baseline.
    BOX             : Draw a frame for data.
    CALIBRATE       : [Re-]Calibrates a spectrum.
    DROP num [ver]  : Take a scan out of the current index.
    DUMP            : List some informations on the R spectrum.
    FILE type name  : Define the input/output files.
    FIND            : Search the input file for observations.
    FOLD            : Folds a Frequency Switched spectrum.
    GET [N]         : Read a scan in the input file.
    HEADER          : Display some header information on the R spectrum.
    IGNORE List     : Ignore scans from the Input file.
    LIST [name]     : List header information about an ensemble of scans.
    MODIFY          : Edit and change the scan header.
    MULTIPLY fact   : Multiply the R spectrum by fact.
    NEW_DATA        : Wait until new data present in input file.
    PLOT            : Plot the observation in R, with box and title.
    SAVE [name]     : Save the current parameters.
    SET             : Enter a value for a parameter.
    SHOW Arg        : Display some parameter.
    SPECTRUM [Yoff] : Plot the R observation.
    SUM             : Add up all the observations of the current index.
    SWAP            : Exchange the contents of the R and T buffers.
    TAG Qual List   : Change the quality of scans in the Output file.
    TITLE           : Write a header above the plotted frame.
    UPDATE          : Update R in the output file.
    WRITE [Scan]    : Write R in the output file.
2 NEWS
      - Exit LAS, welcome CLASS: support for continuum data.
      - Quality flag for scans: new commands IGNORE and TAG, command  DELETE
        has been deleted.
1 LIST
        LAS\LIST [Name] [/BRIEF] [/LONG] [/OUTPUT File]

    List header information about an ensemble of Observations.  LIST is used
    for  a  quick  look  to  Observation headers, in a more or less detailed
    format. Name specifies the file to be listed: IN or OUT ; if Name is not
    present,  the  current index is listed. A medium-sized format is used by
    default.
    /BRIEF          : Brief format (Observation numbers and version numbers)
    /LONG           : Long format
    /OUTPUT File    : Send the list to a disk file instead of the terminal

1 MODIFY
        LAS\MODIFY Item [Values...]

    This is a general  purpose  command  to  edit  and  change  the  current
    observation  header.  Some  actions  are  merely presentation "details",
    others do affect  the  information  in  the  observation.  Among  these,
    RECENTER,  WIDTH, IMAGE and SWITCH_MODE are typically used only when the
    software did not agree  with the hardware when  the  spectra  was  taken
    (i.e.  when  the  information  in the observation header is wrong). They
    should be used with caution.

    MODIFY actions are limited. You should  use  the  SIC\  command  LET  to
    modify  header  variables  which  are  not  available  within the MODIFY
    command (Caution: this is the rope to hang you).

2 FREQUENCY
        LAS\MODIFY FREQUENCY Rfreq

    Compute the velocity scale corresponding to a new rest frequency  Rfreq.
    The sky frequency scale is not modified.

2 OFFSETS
        LAS\MODIFY OFFSETS O1 O2

    Change the offsets. This may be required when you average  spectra  from
    different  offsets,  because  the  resulting  "position"  is meaningless
    (usually the position of the first observation added).

2 BLANKING
        LAS\MODIFY BLANKING NewBlank

    Change the blanking value in both header and data. This may be  required
    before  you  can  build  a  consistent  strip  or cube, specially if the
    spectra were initially loaded from a FITS tape.

2 RECENTER
        LAS\MODIFY RECENTER Rrchan

    Change the reference channel in order to change the velocity,  frequency
    and  image  frequency scales. The sky frequency scale is also altered in
    this command.

2 BANDS
        LAS\MODIFY BANDS

    Exchange signal and image bands. This allows line fitting on image  band
    for  example.  Currently,  the spectrum is not rescaled even if the band
    ratio is not 1.

2 LINENAME
        LAS\MODIFY LINENAME "New Name"

    Modify the line name (for bookeeping).

2 VELOCITY
        LAS\MODIFY VELOCITY Rvoff

    Compute the image and rest frequencies corresponding to a  new  velocity
    (in km/s). The sky frequency scale is unchanged by this command.

2 WIDTH
        LAS\MODIFY WIDTH Rfres

    Change the frequency resolution (in MHz).

2 IMAGE
        LAS\MODIFY IMAGE Rimage

    Change the image frequency (in MHz).

2 BEAM_EFF
        LAS\MODIFY BEAM_EFF Value

    Change the beam efficiency. If the beam efficiency previously had a  non
    zero  value,  the  spectrum  is  rescaled  according  to  the new value.
    Otherwise, only the beam efficiency is set to the new value.

2 TELESCOPE
        LAS\MODIFY TELESCOPE Name

    Change the telescope name, for instance from IRAM-30M to 30M-MRT.

2 POSITION
        LAS\MODIFY POSITION Lambda Beta

    Change the central  position  for  the  source.  The  offsets  are  also
    modified,  as  to  be  consistent  with  the  new central position. This
    command is usefull  when  different  parts  of  one  source  are  mapped
    relative to several reference positions.

2 SYSTEM
        LAS\MODIFY SYSTEM System

    Change the System in which the center of projection (central position of
    the  source)  has  been defined. Valid systems are GALACTIC, EQUATORIAL,
    HORIZONTAL and UNKNOWN. This command is  typically  used  for  "foreign"
    data  when  the SYSTEM information has not been decoded correctly by the
    conversion package.

2 SWITCH_MODE
        LAS\MODIFY SWITCH_MODE Switching_mode Nphase Off_1 Time_1 Weight_1

    Change the description of the switching mode. This command is  typically
    used  for  "foreign"  data  when  this  information has not been decoded
    correctly by the conversion package.

    For each phase, one should specify:
      - the offset for the phase (in MHz for frequency switching, in current
        angular unit otherwise).
      - the duration of the phase (in seconds)
      - the weight given to phase (arbitrary units)
1 MULTIPLY
        LAS\MULTIPLY Fact

    Multiply the R Observation by Fact. MULTIPLY leaves  the  T  Observation
    unaffected.  Note  that  Tsys  is also multiplied by the same (absolute)
    factor to keep proper weights. If only the data is to be multiplied, use
    the SIC\LET command on array RY:

1 NEW_DATA
        [LAS\]NEW_DATA

    Waits until new data has been written to the input file,  then  makes  a
    new  index  from all new data. The type of observation can be changed by
    this command, but the index will contain only observations of one  type.
    Selection criteria defined by command SET are ignored.

    This command can be used to make  a  quick  look  or  analysis  of  data
    produced  by  a real time acquisition system. Caution: only two programs
    should access the input file simultaneously, one for writing  the  other
    for reading.

1 PLOT
        LAS\PLOT [/SCAN]

    Display the Observation in  R.  PLOT  is  equivalent  to  the  following
    sequence of commands:
        CLEAR    BOX    SPECTRUM    TITLE
    PLOT /SCAN will plot an on-the fly scan as a  2-dimensional  image  with
    velocity/frequency in the X axis, record number in the Y axis, intensity
    being  rendered  as  grey/color  scale.  Entering  command  POPUP  after
    PLOT/SCAN  enables  displaying  a  single spectrum, selected by clicking
    with the middle button of the mouse.

1 SAVE
        LAS\SAVE Name

    SAVE creates a procedure file of name "Name.CLASS", containing  all  the
    current  parameters  of  the  program.  This file may be executed at any
    time using the @ command: just type "@ name" after the LAS>  prompt,  or
    pass   "@ name"   as   a   parameter  when  invoking  CLASS  (by  typing
    "CLASS @ name").  This file is composed of standard CLASS  commands, and
    may be edited with any text editor.

1 SET
        LAS\SET something [value1 [value2 [...]]] [/NOCURSOR]

    This command is used to set a  value  for  a  CLASS  parameter.   If  no
    argument is given, the default value for the parameter will be restored.

2 DEFAULT
        LAS\SET DEFAULT

    Restore most (hopefully all) parameters  to  their  default  value.  The
    default  values  for  individual  parameters  are  documented  under the
    corresponding subtopic.

2 PROCESSING
        The  following  SET  Parameter  commands  control  data   processing
    options:
    LAS\SET ALIGN Type Range
    LAS\SET BAD Check
    LAS\SET BASE arg
    LAS\SET CALIBRATION [Beam_Tol [Gain_Tol]] or OFF
    LAS\SET CURSOR Arg
    LAS\SET MASK [ml1 ml2 [...]]
    LAS\SET MATCH Tol
    LAS\SET NOMATCH
    LAS\SET TYPE CONTINUUM or LINE or SKYDIP
    LAS\SET VARIABLE Section_Name [Keyword]
    LAS\SET VELOCITY L[sr]H[eliocentric]A[utomatic]
    LAS\SET WEIGHT type
    LAS\SET WINDOW [wl1 wu1 [wl2 wu2 [...]]]

2 DISPLAY
        The following SET Parameter commands affect data display:
    LAS\SET CURSOR Arg
    LAS\SET FORMAT Type
    LAS\SET LEVEL interactive_min_value logfile_min_value
    LAS\SET MODE A [Type]
    LAS\SET PLOT type
    LAS\SET SYSTEM Type [Equinox]
    LAS\SET UNIT Lower [Upper]
    LAS\SET VARIABLE Section_Name [Keyword]
    LAS\SET VELOCITY L[sr]H[eliocentric]A[utomatic]

2 SELECTION
        The following SET Parameter commands affect data selection in FIND:
    LAS\SET ANGLE Unit
    LAS\SET LINE NAME
    LAS\SET MATCH Tol
    LAS\SET NOMATCH
    LAS\SET NUMBER n1 n2
    LAS\SET OBSERVED d1 d2
    LAS\SET OFFSETS o1 o2
    LAS\SET POSANGLE amin amax
    LAS\SET QUALITY q
    LAS\SET RANGE West East South North
    LAS\SET REDUCED d1 d2
    LAS\SET SCAN s1 s2
    LAS\SET SOURCE name
    LAS\SET SYSTEM Type [Equinox]
    LAS\SET TELESCOPE Name
    LAS\SET TYPE CONTINUUM or LINE or SKYDIP

2 ALIGN
        LAS\SET ALIGN Type Range

    Defines the way the spectra are aligned to be added together.  Type  may
    be  C[hannel],  V[elocity]  or  F[requency]  for  spectra,  C[hannel] or
    P[osition] for drifts. The range may be I[ntersect] or C[omposite].  The
    default  is  CHANNEL  INTERSECT.  This  means  that  continuum drifts in
    opposite directions are not  properly  added:  ALIGN  Position  must  be
    specified for that.

2 ANGLE
        LAS\SET ANGLE Unit

    Specify the angle unit for offsets. May be R[adian],  D[egree],  M[inute
    of  arc],  S[econd  of  arc].  Default is MINUTE. The ANGLE unit is also
    used to display Continuum drifts.

2 BAD
        LAS\SET BAD Check

    Specify the way ACCUMULATE and SUM behaves in the case of bad  channels.
    Check  may  be OR or AND.     Default is OR, i.e.  the output channel is
    bad if any of the input channels is bad.

2 BASELINE
        LAS\SET BASELINE arg

    Specify the degree of polynomial baselines to be subtracted.  Default is
    1.

2 CALIBRATION
        LAS\SET CALIBRATION [Beam_Tol [Gain_Tol]] or OFF

    Specify the tolerance on the Beam efficiency (Beam_Tol) and  gain  image
    ratio  (Gain_Tol),  on turn or calibration checking.  A value of 0 means
    no check. The default values are 0.02 and 0 respectively.  These  values
    are  used by command SUM to verify that the calibration is coherent, and
    by command WRITE which  writes  the  corresponding  information  in  the
    output  file  only  if  Beam_Tol is non zero. Note that because the beam
    efficiency is less than 1, you could  use  Beam_Tol=1  to  suppress  the
    calibration checking but still write the information.

2 COORDINATES
        LAS\SET COORDINATES [Automatic|Galactic|Equatorial]

    Specify the system used when displaying the absolute coordinates of  the
    source.

2 CURSOR
        LAS\SET CURSOR Arg

    Activates or deactivates the use of cursor for the commands SET  WINDOW,
    SET  MASK, SET MODE and LINES, according to the value of Arg: ON or OFF.
    Default is OFF.

2 EXTENSION
        LAS\SET EXTENSION Ext

    Defines the default extension for input and output  files.   Default  is
    .BUR.

2 FIND
        LAS\SET FIND UPDATE|NOUPDATE

    FIND will check (or not) for new scans  in  the  input  file  (see  FIND
    New_Data).

2 FORMAT
        LAS\SET FORMAT Type

    Set the format of the title of observations plotted. The same format  is
    used  by  the  LIST command. The format may be BRIEF (Observation number
    and version,  Source  name,  Line  name,  Telescope  name  and  position
    offsets),  LONG   or  FULL which is similar to the long format, but also
    displays the list of original Scans. The default is BRIEF.  FULL  format
    is always used for command HEADER.

    Other keywords can be specified to indicate which  type  of  information
    should be written for the LONG and FULL formats. This is done by command
        LAS\SET FORMAT Keyword [ON]  [OFF]  (ON  to  write  the  information
    corresponding  to the specified keyword, OFF to ignore it). The keywords
    are
      - POSITION for position of the source, offsets,  type  of  coordinates
        and Epoch
      - QUALITY for the Opacity, System temperature, Elevation,  Integration
        time.
      - SPECTRAL for the number of channel, reference channel, velocity  and
        resolution, signal and image frequency and resolution.
      - CALIBRATION for the beam and forward efficiencies and the gain image
        ratio.
      - ATMOSPHERE for the water vapor content, pressure,  temperatures  and
        opacities in signal and image bands.
      - CONTINUUM for continuum drift information
      - ORIGIN for the list of added scans.
    The default is Position - Quality - Spectral  for  spectra,  Position  -
    Quality  - Continuum for drifts. A line of general information is always
    written in any case.

2 LEVEL
        LAS\SET LEVEL interactive_min_value logfile_min_value

    Sets the level (0 to 10) of informational messages returned to the  user
    in  interactive  mode  and  in  the  message file (CLASS.MES). The level
    attributed to a message (i.e., a warning message, an  error  message,  a
    severe-error  message)  is  somewhat  dependent of the good humor of the
    programmer, but typically aknowledgement messages  range  0-2,  warnings
    3-5,  errors  6-8,  severe-errors  9-10.  To prevent printing of message
    milder than 7 at interactive level and 4 in CLASS.MES, type

    LAS\SET LEVEL 7 4

2 LINE
        LAS\SET LINE Name

    FIND will select all observations according to the specified line  name.
    Default  is  *. A syntax like NAM* can be used to find observations with
    line names beginning by NAM.

2 MASK
        LAS\SET MASK [ml1 ml2 [...]]

    Defines a mask for the Gaussian fits by its boundaries. The cursor  will
    be  used to specify missing arguments if SET CURSOR is ON, unless option
    /NOCURSOR is present. When using the cursor, enter: N to enter a  value,
    C to cancel the last entry, H for help, E for exit.  Default is no mask.
    The boundaries are in current unit.

2 MAP
        LAS\SET MAP [Clear|Normal]

    Will Clear (or Not) the screen before processing a MAP command. However,
    a  "MAP  Where" command does not clear the screen even in a "LAS\SET MAP
    Clear" mode.

2 MATCH
        LAS\SET MATCH Tol

    Turn on the checking of position-matching  in  ACCUMULATE.  Tol  is  the
    position  tolerance  in  current  units.  The  default  is  SET  MATCH 2
    (arcsec).  The tolerance is also used in  FIND,  MAP  and  a  few  other
    commands such as CUBE.

2 MODE
        LAS\SET MODE A [Type]

    Select the scale mode for axis A (X or Y). The mode can  be  TOTAL  (all
    data  plotted),  AUTO (limits as found in the input file), or Amin, Amax
    for fixed limits. If no Type argument is given, the graphic cursor  will
    be  invoked  to  define  the  limits  if  SET CURSOR ON is selected. The
    default is AUTO.

2 NOMATCH
        LAS\SET NOMATCH

    Turn off checking of position-matching in ACCUMULATE and SUM. This  does
    not change the tolerance for the other functions like FIND and MAP.

2 NUMBER
        LAS\SET NUMBER n1 n2

    FIND will select all  Observations  with  numbers  between  n1  and  n2.
    Default is * *.

2 OBSERVED
        LAS\SET OBSERVED d1 d2

    FIND will select all Observations with observing dates  between  d1  and
    d2.   Dates  are specified as DD-MMM-YYYY (i.e. 14-JUL-1789). Default is
    * *.

2 OFFSETS
        LAS\SET OFFSETS o1 o2

    FIND will select all observations  with  offsets  within  the  specified
    tolerance  (SET MATCH) of o1 and o2. See also SET RANGE.  Default is * *
    (select all offsets).

2 PLOT
        LAS\SET PLOT type

    Set the plotting type for the spectra: N[ormal]  for  broken  lines,  or
    H[istogram]. Default is normal (50% faster plot).

2 POSANGLE
        LAS\SET POSANGLE amin amax

    Specify the position angle range (continnum drifts only) for  subsequent
    searches.

2 QUALITY
        LAS\SET QUALITY q

    FIND will select only observations of quality better than Q  (i.e.  less
    than  Q).  When  originally  written,  unless  the real time acquisition
    system detected a severe problem, all observations  have  quality  0,  a
    priori the best. The quality flag of an observation can be changed using
    the TAG command. See HELP TAG for the recommended quality scale.

2 RANGE
        LAS\SET RANGE West East South North

    FIND will select all observations with offsets in the  specified  range.
    Default is * * * *.

2 REDUCED
        LAS\SET REDUCED d1 d2

    FIND will select all observations with reduction dates  between  d1  and
    d2.   Dates  are specified as DD-MMM-YYYY (i.e. 14-JUL-1789). Default is
    * *.

2 SCAN
        LAS\SET SCAN s1 s2

    FIND will select all observations with Scan numbers between s1  and  s2.
    The  Scan  number,  attributed  by the on-line acquisition system may be
    different from the observation number which is used by CLASS to refer to
    the observations.  Default is * *.

2 SOURCE
        LAS\SET SOURCE name

    FIND will select all scans  according  to  the  specified  source  name.
    Default is *. Syntax like NAM* can be used to find all observations with
    source name beginning by NAM.

2 SYSTEM
        LAS\SET SYSTEM Type [Equinox]

    Specify the coordinate system to  be  used.  Type  may  be  E[quatorial]
    followed  by an epoch, G[alactic], or A[utomatic]. Default is Auto, i.e.
    uses the type found in the data  file.  If  the  equinox  of  Equatorial
    coordinates  is  not  specified, the previous value is used. The initial
    default is 1950.00.  Coordinates and offsets are automatically converted
    to  the specified coordinate system and precessed to the specified epoch
    if needed.

2 TELESCOPE
        LAS\SET TELESCOPE Name

    FIND will select all scans according to the  specified  telescope  name.
    Default is *. Syntax like NAM* can be used to find all observations with
    telescope name beginning by NAM.

2 TYPE
        LAS\SET TYPE CONTINUUM or LINE or SKYDIP

    Defines on which type of data the program is working.
      - LINE (or SPECTROSCOPY)  (the  default  when  entering  LAS)  selects
        Spectral  Line  data  only,  and  the  program  prompt is LAS> (Line
        Analysis System).
      - CONTINUUM selects continuum drifts results  only,  and  the  program
        prompt changes to CAS> (Continuum Analysis System).
      - SKYDIP selects only skydips, and the prompt changes to SAS>
    In CONTINUUM mode, a continuum drift is treated as a spectrum  would  be
    in  LINE  mode.  You can add drifts, subtract baseline, make gauss fits,
    change plotting scales etc... The  current  angular  units  is  used  in
    plots.  SKYDIP  mode has very limited capabiblities: only command REDUCE
    may be used to analyse the SKYDIP results.

2 UNIT
        LAS\SET UNIT Lower [Upper]

    Specify the unit to be used for the lower and  upper  X  axis.   Allowed
    units  are  C[hannel],  F[requency], [Image] and V[elocity].  Default is
    Velocity. For Continuum drifts, this unit is ignored,  but  the  angular
    unit specified by SET ANGLE is used.

2 VARIABLE
        LAS\SET VARIABLE Section_Name [Keyword]

    Declare SIC variables corresponding to section of the header  of  the  R
    observation.  The  header sections are POSITION, SPECTRO, BASE, HISTORY,
    PLOT, FSWITCH, CALIBRATION, SKYDIP, GAUSS, SHELL, NH3 (or  HFS),  DRIFT,
    BEAM,  and  CONTINUUM. Defining these SIC variables allows to access the
    header for mathematical computations using SIC facilities. All variables
    are  declared  as  readonly,  unless Keyword WRITE is specified as third
    argument.  If Keyword OFF is specified, the corresponding SIC  variables
    are  deleted  (to  save space since the total number of SIC variables is
    limited).

    The SIC variables have the name of the corresponding  FORTRAN  variables
    stripped  from the first character (always R in the FORTRAN code).  They
    are defined below

                  GENERAL General parameters, always present:
    INTEGER MGEN
    INTEGER MGEN2
    PARAMETER (MGEN=9,MGEN2=11)
    INTEGER  RNUM           ! Observation number
    INTEGER  RVER           ! Version number
    INTEGER  RTELES(3)      ! Telescope name
    INTEGER  RDOBS          ! Date of observation (code)
    INTEGER  RDRED          ! Date of reduction (code)
    CHARACTER RCDOBS        ! Date of observation (in clear)
    CHARACTER RCDRED        ! Date of reduction (in clear)
    INTEGER  RTYPEC         ! Type of coordinates
    INTEGER  RKIND          ! Type of data
    INTEGER  RQUAL          ! Quality of data
    INTEGER  RSCAN          ! Scan number
    REAL*8  RUT             ! UT of observation
    REAL*8  RST             ! LST of observation
    REAL*4  RAZ             ! Azimuth
    REAL*4  REL             ! Elevation
    REAL*4  RTAU            ! Opacity
    REAL*4  RTSYS           ! System temperature
    REAL*4  RTIME           ! Integration time

                         POSITION Position information:
    INTEGER MPOS
    PARAMETER (MPOS=11)
    INTEGER  RSOURC(3)           ! Source name
    REAL*4  REPOCH               ! Epoch of coordinates
    REAL*8  RLAM                 ! Lambda
    REAL*8  RBET                 ! Beta
    REAL*4  RLAMOF               ! Offset in Lambda
    REAL*4  RBETOF               ! Offset in Beta
    INTEGER  RPROJ               ! Projection system

                SPECTRO Spectroscopic information (for spectra)
    INTEGER MSPEC
    PARAMETER (MSPEC=18)
    INTEGER  RLINE(3)            ! Line name
    REAL*8  RRESTF               ! Rest frequency
    INTEGER  RNCHAN              ! Number of channels
    REAL*4  RRCHAN               ! Reference channels
    REAL*4  RFRES                ! Frequency resolution
    REAL*4  RFOFF                ! Frequency offset
    REAL*4  RVRES                ! Velocity resolution
    REAL*4  RVOFF                ! Velocity at reference channel
    REAL*4  RBAD                 ! Blanking value
    REAL*8  RIMAGE               ! Image frequency
    INTEGER  RVTYPE              ! Type of velocity
    REAL*8  RSKYFR               ! Sky frequency
    REAL*4  RVTELES              ! Velocity of telescope /reference frame

               BASE Baseline information (for spectra of drifts)
    INTEGER MWIND
    INTEGER MBASE
    PARAMETER (MWIND=20,MBASE=4+2*MWIND)
    INTEGER  RDEG                ! Degree of last baseline
    REAL*4  RSIGFI               ! Sigma
    REAL*4  RAIRE                ! Area under windows
    INTEGER  RNWIND              ! Number of line windows
    REAL*4  RW1(MWIND)           ! Lower limits of windows
    REAL*4  RW2(MWIND)           ! Upper limits of windows

                  HISTORY Scan numbers of initial observations
    INTEGER MSEQ
    INTEGER MORIG
    PARAMETER (MSEQ=100,MORIG=2*MSEQ+1)
    INTEGER  RNSEQ               ! Number of sequences
    INTEGER  RSTART(MSEQ)        ! Start can number of seq.
    INTEGER  REND(MSEQ)          ! End scan number of seq.

                         PLOT Default plotting limits.
    INTEGER MPLOT
    PARAMETER (MPLOT=4)
    REAL*4  RAMIN                ! Min Y value plotted
    REAL*4  RAMAX                ! Max Y value plotted
    REAL*4  RVMIN                ! Min X value plotted
    REAL*4  RVMAX                ! Max X value plotted

             FSWITCH Frequency switching information (for spectra)
    INTEGER MXPHAS
    INTEGER MFSW
    PARAMETER (MXPHAS=8,MFSW=2+6*MXPHAS)
    INTEGER  RNPHAS              ! Number of phases
    REAL*8  RDECAL(MXPHAS)       ! Frequency offsets
    REAL*4  RDUREE(MXPHAS)       ! Time per phase
    REAL*4  RPOIDS(MXPHAS)       ! Weight of each phase
    INTEGER  RSWMOD              ! Switching mode (frequency, position...)
    REAL*4  RLDECAL(MXPHAS)      ! Lambda offsets
    REAL*4  RBDECAL(MXPHAS)      ! Beta offsets of each phase

                       CALIBRATION Calibration parameters
    INTEGER MCALIB
    PARAMETER (MCALIB=21)
    REAL*4  RBEEFF               ! Beam efficiency
    REAL*4  RFOEFF               ! Forward efficiency
    REAL*4  RGAINI               ! Image/Signal gain ratio
    REAL*4  RH2OMM               ! MM of water vapor
    REAL*4  RPAMB                ! Ambient pressure (hPa)
    REAL*4  RTAMB                ! Ambient temperature (K)
    REAL*4  RTATMS               ! Atmosphere temp. signal band
    REAL*4  RTCHOP               ! Chopper temperature
    REAL*4  RTCOLD               ! Cold load temperature
    REAL*4  RTAUS                ! Opacity signal band
    REAL*4  RTAUI                ! Opacity image band
    REAL*4  RTATMI               ! Atmosphere temp. image band
    REAL*4  RTREC                ! Receiver temperature
    INTEGER  RCMODE              ! Calibration mode
    REAL*4  RATFAC               ! Applied calibration factor
    REAL*4  RALTI                ! Site elevation
    REAL*4  RCOUNT(3)            ! Power of Atm., Chopp., Cold
    REAL*4  RLCALOF              ! Longitude offset for sky measurement
    REAL*4  RBCALOF              ! Latitude offset for sky measurement

              SKYDIP For Skydips observations. No associated data.
    INTEGER MSKY
    INTEGER MSKYDIP
    PARAMETER (MSKY=10,MSKYDIP=10+4*MSKY)
    INTEGER  RSLINE(3)           ! Line name
    REAL*8  RSREST               ! Rest frequency
    REAL*8  RSIMAG               ! Image frequency
    INTEGER  RNSKY               ! Number of points on sky
    INTEGER  RNCHOP              !    -   -    -    - chopper
    INTEGER  RNCOLD              !    -   -    -    - cold load
    REAL*4  RELEV(MSKY)          ! Elevations
    REAL*4  REMISS(MSKY)         ! Power on sky
    REAL*4  RCHOPP(MSKY)         ! Power on chopper
    REAL*4  RCOLD(MSKY)          ! Power on cold load

                GAUSS Gauss fit results (for spectra or drifts)
    INTEGER MXGAUS
    INTEGER MFIT
    PARAMETER (MXGAUS=5,MFIT=3+6*MXGAUS)
    INTEGER  RNLINE              ! Number of components
    REAL*4  RSIGBA               ! Sigma on base
    REAL*4  RSIGRA               ! Sigma on line
    REAL*4  RNFIT(3*MXGAUS)      ! Fit results
    REAL*4  RNERR(3*MXGAUS)      ! Errors

            SHELL "Stellar shell" profile fit results (for spectra)
    INTEGER MSHELL
    PARAMETER (MSHELL=43)
    INTEGER  RLSHEL              ! Number of components
    REAL*4  RBSHEL               ! Sigma on base
    REAL*4  RRSHEL               ! Sigma on line
    REAL*4  RNSHEL(20)           ! Fit results
    REAL*4  RESHEL(20)           ! Errors

                 HFS "Hyperfine Structure" profile fit results
                            (for spectra, ex: NH3, HCN)
    INTEGER MNH3
    PARAMETER (MNH3=27)
    INTEGER  RLNH3               ! Number of components
    REAL*4  RBNH3                ! Sigma on base
    REAL*4  RRNH3                ! Sigma on line
    REAL*4  RNNH3(12)            ! Fit results
    REAL*4  RENH3(12)            ! Errors

           ABS "Hyperfine Structure" ABSORPTION profile fit results
                             (for spectra, ex: NH3, HCN)
    INTEGER MABS
    PARAMETER (MABS=35)
    INTEGER  RLABS               ! Number of components
    REAL*4  RBABS                ! Sigma on base
    REAL*4  RRABS                ! Sigma on line
    REAL*4  RNABS(16)            ! Fit results
    REAL*4  REABS(16)            ! Errors

                 DRIFT Continuum drift description (for drifts)
    INTEGER MCONT
    PARAMETER (MCONT=16)
    REAL*8  RFREQ                ! Rest frequency
    REAL*4  RWIDTH               ! Bandwidth
    INTEGER  RNPOIN              ! Number of data points
    REAL*4  RRPOIN               ! Reference point
    REAL*4  RTREF                ! Time at reference
    REAL*4  RAREF                ! Angular offset at ref.
    REAL*4  RAPOS                ! Position angle of drift
    REAL*4  RTRES                ! Time resolution
    REAL*4  RARES                ! Angular resolution
    REAL*4  RCBAD                ! Blanking value
    INTEGER  RCTYPE              ! Type of offsets
    REAL*8  RCIMAG               ! Image frequency
    REAL*4  RCOLLA               ! Collimation error Az
    REAL*4  RCOLLE               ! Collimation error El

             BEAM Beam-switching parameters (for spectra or drifts)
    INTEGER MBEAM
    PARAMETER (MBEAM=5)
    REAL*4  RCAZIM               ! Azimuth of observation
    REAL*4  RCELEV               ! Elevation of observation
    REAL*4  RSPACE               ! Beam spacing
    REAL*4  RBPOS                ! Position angle of beams
    INTEGER  RBTYPE              ! System for angle

        CONTINUUM Double gaussian and baseline fit results (for drifts)
    INTEGER MFCONT
    PARAMETER (MFCONT=19)
    INTEGER  RLCONT              ! Number of components
    REAL*4  RBCONT               ! Sigma on base
    REAL*4  RRCONT               ! Sigma on line
    REAL*4  RNCONT(8)            ! Results
    REAL*4  RECONT(8)            ! Errors

2 VELOCITY
        LAS\SET VELOCITY L[sr]H[eliocentric]A[utomatic]

    Forces the velocity axis values to Lsr or Heliocentric values. Automatic
    reverts  to  the default mode, where the velocity type is taken from the
    header of the spectrum.

2 WEIGHT
        LAS\SET WEIGHT type

    Weighting to be used for summations: T[ime],  E[qual]  or  S[igma]  (for
    1/sigma**2).  The  default  is TIME. Sigma is not recommended unless you
    just made a baseline  fit  before.  Equal  behaves  differently  in  SUM
    (produces the average) and ACCUMULATE (produces the SUM).

2 WINDOW
        LAS\SET WINDOW [wl1 wu1 [wl2 wu2 [...]]]

    Defines one or several line windows to be avoided by BASE when fitting a
    baseline.  The  cursor  will be used to specify missing arguments if SET
    CURSOR is ON, unless option /NOCURSOR is present. When using the cursor,
    enter: N to enter a value, C to cancel the last entry, H for help, E for
    exit.  The boundaries are in current unit. There is no default.


1 SHOW
        LAS\SHOW Arg

    Display some parameter defined by SET. Arg can be "ALL" to  display  all
    parameters specified by SET. See SET command.

1 SPECTRUM
        LAS\SPECTRUM [Yoff]

    Plots the spectrum in the R buffer in the units and  scales  defined  by
    SET  UNIT and SET MODE.  Yoff (unit Kelvins, default 0) is a constant Y-
    offset added to the plotted values (useful to compare two spectra).

1 SUM
        LAS\SUM

    Adds all the spectra of the current index using  the  current  weighting
    function  (SET  WEIGHT)  and  alignment  mode (SET ALIGN).  The position
    coincidence will be checked according to SET MATCH.  The homogeneity  of
    calibration  is  checked according to SET CALIBRATION.  Bad channels are
    handled according to SET BAD.  A sum may be interrupted by <^C>, but the
    results is then undefined.

    If the data are On-The-Fly  scans,  all  the  individual  positions  are
    averaged.
1 SWAP
        LAS\SWAP

    Exchange the contents of the R and T buffers.
1 TAG
        LAS\TAG Quality_Code List_of_Observations

    Attributes a quality to a given list of Observations. Quality_Code is an
    integer in the range 0-9, and the recommended quality scale is
          0 Unknown
          1 Excellent
          2 Good
          3 Fair
          4 Average
          5 Poor
          6 Bad
          7 Awful
          8 Should never exist
          9 Reserved for deleted Observations
    The operation is immediate  and  occurs  in  the  OUTPUT  file  for  all
    versions of all Observations specified in the list. If no list is given,
    the R memory is attributed the specified quality.  A FIND operation will
    only  select Observations of quality better than (i.e. less or equal to)
    the quality specified by the SET QUALITY command,  or  in  the  /QUALITY
    option.

1 TITLE
        LAS\TITLE [/BRIEF] [/LONG]

    Writes the header of the Observation currently in R  above  the  plotted
    data.   The  format used is the one selected by SET FORMAT, which may be
    temporarily overridden by the options.

1 UPDATE
        LAS\UPDATE

    Update the LAST version of the observation in the R buffer in the output
    file  ;  the  update OVERWRITES the observation. If more space is needed
    (e.g., the new  version  has  more  header  information),  an  error  is
    returned.   You  MUST  then  WRITE  the  observation  to  avoid  loss of
    information.  You can update only last versions.  This command  MUST  BE
    USED  WITH  CAUTION  ; in case of complex manipulations of observations,
    you may get confused and erase precious data.

    The only typical case where it may be used is in the following sequence:
        GET Number
        GAUSS or MODIFY
        UPDATE

1 WRITE
        LAS\WRITE [observation]

    Writes the observation  in the R buffer onto the  output  file  ;  if  a
    version of this observation is already in the file, a new version of the
    observation is created. A new observation number  can  be  specified  as
    argument.  The information written depends on the operations done on the
    observation.   Existing  fit  results  are  written.   The   calibration
    information  is  written  only  if  the  calibration is checked (see SET
    CALIBRATION command).

1 END








































