Basic Information on atmos

Task: atmos
Purpose: Generate ATCA-style mosaic file.
Categories: uv analysis

ATMOS takes a list of sources (with RA and DEC), sorts them into
an order to minimise the slew time between the sources, and then
writes out an ATCA-style mosaic file which can be used by the
ATCA on-line system to execute a mosaic observation.

In the mosaic file, the cycles spent on each source is adjusted
to account for the slew time needed to reach each source.

NOTE:
* ATMOS neglects the ATCA's wrap limits. It is
conceivable that the antennas might have to do a pirouette in the
middle of a mosaic block to move from north to south wrap (or visa
versa). This will foul up all of ATMOS's calculations.

* It does not appear that mosaicing is supported in anything but
J2000 coordinates. All coordinates here should be in J2000.

* You must give "sched" a reference position (the positions
in the mosaic file generated by ATMOS will be relative to this
position). ATMOS uses the position of the first source as the
reference position.

Key: source
A text file giving a list of sources. Each line of the file contains
  name ra dec
The source name cannot contain blanks. RA and DEC are given in the
standard Miriad format.

If the source name ends in "C", it is assumed to be a calibrator.
ATMOS assumes that sources follow their calibrator -- the rearrangement
ensures that this continues to be so. 
Note that, for calibrators in a mosaic file, the on-line imaging
software (CASNAP and friends) require names of calibrators to be 10
characters long and end in a "C".

Key: out
Output mosaic text file. Default is mosaic.mos

Key: cycles
Number of cycles to spend on-source at each source. Default is 2.

Key: interval
Integration cycle time. Default is 10 seconds.

Key: origin
The output mosaic file stores positions as an offset from
some position. You have to give this value in your sched file.
The `origin' parameter is used to set this position in ATMOS.
It is an RA and DEC, in the format hh:mm:ss,dd:mm:ss, or decimal hours
and decimal degrees). The default is the position of the first
source in the list. NOTE: The on-line system always slews to the
origin before it starts executing a mosaic. Consequently you
reduce slewing time by using the default.

Key: ref
This gives the name, RA and DEC where the antennas are pointing
before the mosaic sequence is executed (the format for RA is
hh:mm:ss, or decimal hours; and for declination is dd:mm:ss, or
decimal degrees). The default is the RA and DEC of the first
source to be observed (i.e. already on source).

Key: lst
Start time, given either in the format hh:mm:ss or decimal
hours. The default is the reference RA.

Key: options
Extra processing options. Minimum match is supported. Possible
options are:
  fixed  Do not do the travelling salesmen problem, just output
         the source list in the order given.

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