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VLA Scheduling Page
This page allows specifying the ending criterion for a scan as either:
- Duration: the total length of the scan (includes move time).
- Dwell time: The amount of time on source.
- Stop LST: The LST at which the scan is to stop.
The right had side of this page summarizes the current scan
information giving start and stop times, Azimuth and Elevation of the
source etc.
Any Error or Warning messages (as space allows) are displayed at the
botton of the summary.
This page allows control over cable wrap (
"Wrap"
) and over-the-top
(el>90) observations (
"Plunge"
).
A popup dialog can be invoked to give information about
antenna shadowing.
Reschedule Button
Compute (or recompute) the observing schedule from information
entered in the Scheduling Page for the entire Observe List. Before
scheduling, you should have set the start time for the first observation in
the
Starting Conditions Page
from the Options menu.
After scheduling has been performed, you should make sure that no
errors were detected.
This may be done by creating a report using the Report menu, or by
scanning the individual observations on the Scheduling Page.
Scheduling may also be performed from the Schedule Menu.
Duration
The duration of the observation in sidereal time.
The duration is from the start of the present observation to the start
of the next, including the time to reposition the array.
The duration of all sources should be specified, together with the
starting LST for the first source specified in the options menu.
The duration is specified as "hh mm ss".
Hitting Return (Enter) on the keyboard with the cursor in the Text
Field or clicking on the "Verify" button will cause the value to be
read and checked.
A "*" after the Duration label indicates that the duration has been
specified as the termination criterion from this scan.
Dwell
The Dwell Time (time on source) of the observation in sidereal time.
The dwell is estimated from the start of the present observation to
the start of the next excluding the time to reposition the array.
The dwell time on a source may be specified instead of the duration,
which is the normal case.
The Dwell Time is specified as "hh mm ss".
Hitting Return (Enter) on the keyboard with the cursor in the Text
Field or clicking on the "Verify" button will cause the value to be
read and checked.
A "*" after the Dwell label indicates that Dwell time has been
specified as the termination criterion from this scan.
Stop LST
The ending Local Sidereal Time for this scan.
This will usually be computed from the starting LST of the first
source and the durations of all previous sources.
If the field is entered, is entered, then it is used.
If conflicts occur when the scheduling is calculated, an error message
will appear.
It is generally not a good idea to use Stop LST for the stopping
criterion for scans.
The Stop Local Sidereal Time is specified as "hh mm ss".
Hitting Return (Enter) on the keyboard with the cursor in the Text
Field or clicking on the "Verify" button will cause the value to be
read and checked.
A "*" after the Stop LST label indicates that Stop LST has been
specified as the termination criterion from this scan.
Wrap
Wrap specifies the range of azimuth that the scheduler is allowed to
position the array.
There are three choices:
- blank: Allow scheduling to move to the closest position,
using full range of azimuth from -85 to 445 degrees.
- left: Force the azimuth into the range -85 to 275 degrees.
- right: Force the azimuth into the range +85 to 445 degrees.
The VLA on-line system (hopefully) makes the same decision as OBSERVE!
Plunge
Plunge specifies whether the array can use an elevation that is
greater than 90 degrees, or go "over the top."
The normal condition when the field is unspecified, is to force the
elevation to be less than 90 degrees.
There are three choices:
- blank: Allow scheduling to move to the closest position,
even if it involves moving over the top.
- down: Force the elevation to be less than 90 degrees.
- up: Force the elevation to be greater than 90 degrees.
"Over-the-top" observations are generally considered a bad thing.
Display Shadowing
Selection this button will pop up a dialog telling about any shadowing
of one antenna by another,