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VLA Fast Switch Page
This page will only be displayed if the "Offset Mode" item on the Source
page is set to "Fast Switching". Fast Switching is used to switch rapidly
between two sources using an offset card, rather than a long series of
source cards. The position of the "primary" source is specified on the
Source page; that of the "secondary" source, on this page. This mode
avoids the twenty second start-up time encountered with source cards,
and allows for total cycle times as short as 40 seconds. The Fast Switch
mode also gives much shorter OBSERVE files, which are much easier to
alter in real time. These fast cycle times generally imply one should
use short integration times, e.g. 3.3 seconds. The cycle times and
secondary source position are specified on this Page.
The source names in the resulting data file will be derived in an
obvious way from the source positions. The "primary" and "secondary"
sources will therefore be stored correctly as different sources in AIPS.
IF for Beam Size
IF for beam size: (options: blank, A, B, C, D) This should be left blank
for Fast Switching observations, unless you're a pundit. If you're a
pundit, you don't need help.
RA and DEC
The position of the "secondary" source. This is assumed to be in the
same coordinate system (B1950, J2000, or of date) as the primary source,
whose position is given on the Source page.
CalCode
Cal Code for "secondary" source. JObserve does not automatically
recognize calibrators on this page, so this must be entered manually.
Primary Duration
How long (in seconds; including move time!) to sit on the "primary" source
(the one whose position is specified on the Source page). THIS MUST BE
A MULTIPLE OF 10 SECONDS.
If this duration is short remember to set an even shorter integration
ime on the Source page -- otherwise all your data may be flagged as
"not on source"! The scan will be made up of many observations of the
primary and secondary sources, as many cycles as can fit in the dwell
time specified on the Scheduling page.
Secondary Duration
How long (in seconds; including move time!) to sit on "secondary" source
(the one whose position is specified on this Page page). THIS MUST BE
A MULTIPLE OF 10 SECONDS.
If this duration is short remember to set an even shorter integration
ime on the Source page -- otherwise all your data may be flagged as
"not on source"! The scan will be made up of many observations of the
primary and secondary sources, as many cycles as can fit in the dwell
time specified on the Scheduling page.