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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: use VLA on-line system default (do not allow elevations
greater than 90 degrees).
- 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.