next up previous contents
Next: Keyin Input for Plotting Up: INTRODUCTION Previous: A Minimal Schedule for   Contents


SCHED has the ability to plot the u-v coverage and beam of sources in a schedule and to plot azimuth, elevation, hour angle, or paralactic angle against any of those quatities or against UT or GST for one to all stations in a schedule. These plots are useful for assessing the quality of the schedule. SCHED can also plot the positions of the sources in a schedule in RA and DEC and plot the positions of all other sources in the specified catalog. The latter is useful for identifying candidate calibrators. The plots can be very useful for planning observations, both at the proposal stage and as the schedule is prepared. For this use, see the section on planning and for a very simple example schedule for obtaining plots of hypothetical schedules, see the second example in the Examples section.. Some of the other examples are also oriented toward planning VLBA and VLA observations.

To cause SCHED to make plots, specify PLOT somewhere in the input. Since it is unlikely that this will be desired in the final run of the program, it is best to start a plotting session interactively and then specify PLOT and use SCHedule to specify the input file. Thus, you would type (on a unix box, anyway):

plot  schedule=bv016d.key /

(substituting your file for the bv016d.key.

The plotting utilizes the PGPLOT subroutine library written by Tim Pearson used by the other Caltech Package programs and in wide use in astronomy. Be sure that the environment variables PGPLOT_DIR is set to the location of the PGPLOT libraries on your system and that PGPLOT_FONT is set the the location of the PGPLOT font files if that is different from PGPLOT_DIR.

If PLOT has been invoked, SCHED will proceed to read all of the input files, check the schedule, and do any requested optimization normally. It will write the summary file, but will not write the antenna specific files, at least until later. The summary file will be closed and can be examined while in the plotting session. This may be useful in studying details of what is being plotted.

When the plotting session begins, SCHED opens a control panel with a variety of buttons that can be clicked with the mouse. It also writes some instructions to the window in which SCHED is being run. On the control panel, the left most column has buttons that either select different control functions (items to the right will change) or cause something to happen. The latter options include actually drawing a plot (PLOT), closing the plot (CLOSE), restarting the program to read a new input file (RESTART), continuing to (FINISH) the rest of SCHED (only allowed if neither RESTART or OPTMODE=UPTIME were used), exit the program (EXIT), or revert the the older style terminal input (TERM) described below. The FILES options allows changing output from the terminal to postscript or other files and allows restriction of plots to scans with specific setup files. The OPTIONS button allows selection of colors and line widths. The AXIS button allows selection plot type and axis scales. The SOURCES button (default on wakeup) allows selection of antennas and sources. Antennas can be selected both for plotting at all and for highlighting in red. The use of the buttons should be fairly intuitive and won't be documented extensively here. Some information included in the descriptions of the terminal input below also applies to interactive operation so it is worth reading through the documentation quickly.

Many thanks to Franco Tinarelli of Bologna for providing the code for the plot control.

Note that, if elevation is plotted against azimuth, the horizon, as specified in the stations catalog, will be plotted in addition to the tracks followed by the sources.

If the RD Plot option is selected, the location on the sky of each source in the schedule is shown. This particular plot option has acquired a number of interactive capabilities. It is possible to zoom in on a region, to look for calibrators around a target location, to show (as calibrators) all sources in the catalog, not just those listed in the schedule, and to label the source and catalog names. These capabilities should be useful in attempts to locate calibrators near reference sources. Currently, a rectangular coordinate system is used for the displays, but a more general projection scheme is under development.

Plots are made, of whatever quantities are specified, by drawing a line from the value at the beginning of each scan to the value at the end of the scan. Thus, if you have very long scans, the individual line segments may become apparent and the plot will not be an exact representation of the data that will be collected.

The RESTART option is especially interesting for experiment planning. It causes SCHED to return to the beginning of the program, read and process the input file again, and return to the plot section, remembering the current plot inputs. If the input file has been changed in any way, those changes will be reflected in the new plots. Thus scan times can be changed, new sources specified etc. This is useful, for example, in exploring the u-v coverage for various sources (much like the Caltech program HAZI) or determining the times that various sources are visible (like the Caltech program UPTIME). It is more flexible than the other programs because you have full control of the schedule so, for example, the u-v coverage from multiple snapshots can be explored. Because it is possible, by deleting some parameters from the input file, to cause SCHED to get confused about the value of some of the parameters for which only one value per project is accepted, the FINISH option is locked out after a RESTART. If a RESTART option has been used, it will be necessary to rerun the program from scratch to get final output schedules. Since you have been modifying the input file on each restart, this should not be a problem.

In older versions of SCHED or if the TERMINAL button is pressed, the plot control is from the terminal window using KEYIN input as described below. This form of input will probably be removed eventually unless there is demand to keep it.

next up previous contents
Next: Keyin Input for Plotting Up: INTRODUCTION Previous: A Minimal Schedule for   Contents
Craig Walker 2014-06-17