- #Bandwidth
- For each of the two frequencies (# is 1 or 2), you
can specify a bandwidth. (This field is most easily specified by setting
the correlator configuration, as that necessarily also specifies the
respective bandwidths.) The bandwidth must be one of 4, 8, 16, 32, 64
or 128MHz. There are certain restrictions on what combinations of
bandwidths you can use for the first and second frequencies. A general
rule is that the second frequency can only be 16, 64 or 128MHz, but you
should check with the correlator configuration you wish
to use. (See also dual).
- #Frequency
- This field sets the first or second frequency (#
can be 1 or 2, 1 is default), as the ATCA is capable of observing with
two different frequencies simultaneously. The central frequencies must
be an integer number of MHz.
For obvious reasons, any pair of frequencies must both be using the
same feed horn. Additionally, 12mm and 3mm frequency pairs must be
within 2.7 GHz of each other.
ATCASCHED will warn you if your frequencies disobey these rules. Also,
it will display a message warning of
the nearest birdie (and trapped modes)
within the specified
bandwidth.
1frequency and 2frequency are often abbreviated as
1freq and 2freq. Frequency range information is available.
It is sometimes possible to get observe the bands specified.
If you are interested, send your questions to
narrabri@atnf.csiro.au.
While it is possible to observe with both frequencies set to the same
value, you do not gain a 
benefit in signal-to-noise as the two
frequencies are derived from the digitisation of the same RF signal, not
independent receivers. If you are only using one frequency, the second
frequency will not be displayed until you request it with the dual
field or specify a value for 2freq or 2band, etc.
- #Hanning
- This can be used to Hanning smooth the data written
to the RPFITS file at each frequency and is set to ON or
OFF. This field is used only when 1line
or 2line is set. (See also dual).
- #Line
- This can be either ON or OFF for
either frequency. If it is set to ON, you are given the
options of 1start, 1stop and 1hanning or the
second frequency equivalent. (See also dual).
- #Start & #Stop
- These can be used to restrict the channel
range of data (integer values only) from the correlator that is
written to disk in the RPFITS file. It is used only when 1line
or 2line is set. (See also dual).
- Averaging
- The averaging parameter specifies
how many cycles to average together when writing the data out to
disk (RPFITS file). Averaging will restart on source and frequency
changes. On-line you will still see the full time resolution data
(eg in VIS). Default is to set the averaging to 3 cycles.
- Calcode
- A flag used to specify if a certain source is used as
a calibrator. It should be either C (for a calibrator) or
blank (for a non-calibrator). For baseline solutions, the calcode
is set to B, a feature that should not be used by normal observers.
If you use the cat command to load in calibrators, the
calcode is set to C automatically. The
calcode flag is reset to blank after you add the scan to avoid
inadvertently calling a target source scan a calibrator scan.
The ASSISTANCE program makes use of the calcode field to
determine the level of on-line checking that is done. If a calibrator
scan is indicated, the checks (for stable amplitude, small delays,
closure phase, etc.) are more stringent. If you don't set the
calibrator scan to calcode=C then you will miss out on these
checks. On the other hand, most target sources have structure and
insufficient flux, so
ASSISTANCE would sound alarms continuously if a source like that
was marked as a calibrator scan.
Note: When using FULL_8_2048, i.e., only the
XX polarisation product, it is HIGHLY advised not to set
calcode C for your calibrators, because ASSISTANCE will not accept the
absence of the YY polarisation product.
- Config file
- The setup of the correlator is defined in this
file. ATCASCHED checks that the specified file exists. A directory
of all known files will be given if the specified file does not exist.
If null is specified the existing configuration file is used.
Observers are advised to fill this field in with their intended
correlator configuration file to avoid mishaps.
- Defcat
- Sets the default catalogue the cat command will use
if not instructed otherwise.
- Dual
- This field may be set as either ON or OFF.
If it is set to ON then the second frequency parameters are made
available, eg 2freq, 2band.
- Envflg
- This
identifier should be used when you are switching between sources
with significantly different
- it requests CAOBS to record the
attenuator and sampler settings associated with each different
envflg and set those values when observing the field again.
Each frequency (modulo 1MHz) allows for up to 128 such flags.
Valid envflg values are from 0 to 127. Use this field when
your observations require frequency switching.
- Epoch
- This defines the coordinate system used for the
ra and dec fields. Four epochs are
recognised:
- J2000 (default),
- B1950,
- GAL (galactic coordinates),
- AZ/EL (horizon coordinates).
Both GAL and AZ/EL are currently interpreted
as RA/DEC by
ATCASCHED, but CAOBS should drive to the correct positions anyway.
Ignore Az/El values given by ATCASCHED listings for these epochs.
Beware: The cat command will set the epoch
to J2000 (as this is used in both AT.CAT and
VLA.CAT), you may need to reset it for subsequent scans.
- LST
- Approximate start time for
the scan - use this to get a fairly accurate picture of the
azimuth and elevations of the sources. This field is not saved in
the ATCASCHED file (except when using timecode = REL), but
is useful to give warnings about sources being below the horizon.
See the newstart command and timecode
parameter.
- Mode
- The mode specifies special observing modes. At present, the
valid options are:
- STANDARD - ie the usual interferometer mode,
- TIEDCIRC - tied-array with circular polarisations,
- TIEDLIN - tied-array with linear polarisations,
- PSR - pulsar binning mode
The PSR mode can be combined with the TIEDCIRC or
TIEDLIN if required,
eg mode=PSR,TIEDCIRC.
The default mode is STANDARD.
- Observer
- This is an ASCII string up to 12 characters long.
It identifies who made the observations. It is not critical to any
of the on-line system and is merely a label for reference.
- Pointing
- This field allows you to specify the pointing mode of
the antennas. Options are:
- GLOBAL - Default. It uses a global (all sky) pointing
model determined at each reconfiguration.
- OFFSET - pointing uses the offsets determined on a nearby
calibrator to improve the pointing locally (near the calibrator) and for
a limited time (offsets are time variable).
- UPDATE - allows you to determine new offsets by
executing a POINT pattern (see sctype) on a
calibrator. Selecting this option will set the scan type to
POINT. Doing an update while not on a calibrator is likely
to ruin your
OFFSET pointing.
If you intend to use reference pointing see the information on
Reference Pointing Observing Mode .
- Project_id
- This is the project identification number (nnn)
allocated to your observing project in the form Cnnn. The
project_id is used by CAOBS to name your data files.
It is important that you fill it in correctly, as it is used for record
keeping and by the ATNF Data Archive. Also local
staff use this information when managing disk space on the observing
machines. The default (C999) is used for system testing and
test files - files labelled as such are usually deleted first! This
field is often abbreviated as proj.
- PtCtrOffset
- Pointing Center Offset allows you to offset the antenna
pointing centre (peak of primary beam) from the array phase centre (as
specified with ra and dec). For detection experiments
of compact sources, it is best to not set the phase centre to the position
of source, as various instrumental artifacts can occur there. It is recommended
to set the phase centre to be away from the source by several synthesised
beams. Note that time and bandwidth smearing increases linearly with
distance from the phase centre, so making the difference very large
degrades your image.
Normally the pointing centre is the same as the phase centre. As best
sensitivity (and cleanest polarimetric response) occurs at the pointing
centre, if the phase centre is set away from the source, it may be desirable
for the pointing centre to be set back at the position of the source.
Unfortunately the way you achieve this through sched is somewhat backwards:
you set a phase centre somewhat different from that of the source, and then
you offset the pointing centre to be back at the source. The
ptctroffset field takes two values, separated by a comma,
specifying 
RA and DEC in whole
seconds and arcseconds respectively (i.e., Pointing-RA = RA + offset-RA,
no cos(Dec) term).
For data taken since October 2003 MIRIAD will correctly track the different
pointing centre (AIPS will not, the treatment in AIPS++ is not known).
- RA & Dec
- These fields define where on the sky you want the array
to point (phase centre). You can use most formats: delineation using
colons (`:'), hours, minutes, seconds (`h',`m',`s') or just by spaces
are all acceptable. The RA and Dec will be in the system defined by
the epoch field thus they can also be used to represent
Azmiuth/Elevation or Galactic Longitude/Latitude. In those cases, the
RA is still in time format, eg Az=90° would be 6h.
- Scan length
-
This indicates the length of time to spend on the
current scan. It is specified in time format and is rather flexible
in its specification (like the RA & Dec fields. Unless
the sctype is set to `dwell', the scan time includes the time to drive
to the source. The scan must be at least four integration cycles long.
See the scantype command.
- Sched file
- The name of the schedule file. Try to use something
meaningful, eg CNNN_1934 where NNN is your program code.
SETUP_1934 and SETUP_0823 are reserved for
system use. SOURCE is the default, so don't use that either.
If a file name is not given
when executing an fsched or write command, this is the name
that is used.
There are two fields that ATCASCHED updates to help you in
your scheduling. You cannot directly modify the following fields:
- Scan number The number assigned to the next scan
added to the schedule (i.e., it is one more than the total number of
scans currently in the schedule file). You can edit a scan, using the
fetch and replace commands, in which case this number indicates
the location of the scan being edited within the schedule.
- The Drive Line When a scan is added to the schedule, or when
changes are made to the schedule, a line is displayed below the Scan
number field. This line displays the azimuth and elevation of the
source at the beginning of the scan. It also shows the drive time from
the last source (stow position if there are no previous sources
entered) and the cable wrap (N or S) assuming you start from stow.
- Sctype
- Specify special scan characteristics:
- DWELL - cause CAOBS to stay on-source for exactly the
specified time. Drive times are not included in the scan length
for DWELL. Bugs: If the drive time to the
first source is longer than the scan length
the first scan will be missed. This is not a problem with subsequent scans.
Also, when using DWELL,
the first scan after a start may be 2 cycles shorter than requested.
- MOSAIC - allows you to indicate that this scan is a
mosaic pattern.
- FREQSW - lets you indicate that this scan is a
frequency switching pattern. Frequency switching
allows you to rapidly switch between frequencies to improve your
coverage.
- POINT - indicates that this scan is to be executed as a
pointing pattern, which can be used to determine offsets for each
antenna. This may be used for global pointing solutions as performed
by local staff, or for reference pointing
during observations.
- Source name
- This is the name of the scan. It is generally the
name of the source that you wish to observe or a calibrator or something
similar. It must be an ASCII string, no more than 9 characters long.
The exact name doesn't matter (it's the RA/Dec/Epoch that points the
array), but it should be something that will help you identify the
field when you are reducing your data. For mosaic names, do not
include the .mos extension (which must be present in the disk file
name).
- Timecode
- Specify the time system for the schedule, this is a
global parameter:
- REL - Default. For most observations, the `timecode'
is only used to calculate the az and el of sources for display in sched:
These positions are generated relative to the LST specified for the
scan of their schedule and the information is not saved anywhere
in the schedule file. (See the newstart command).
- UTC - Absolute times in UTC. CAOBS will wait for
the specified start-time to arrive before starting the scan. This is
used for VLBI observations which need to be synchronised between
stations.
When using ATCASCHED with timecode = UTC, all rise/set times,
el,az positions are completely wrong. Likewise, it also gets
rise/set times wrong for planets.
- UT
- Specifies a start time for the scan. However, it is only used
when timecode=UTC. Must be in the form
DD-MMM-YYYY HH:MM:SS.CC.
