nplots, reftel, IF_index, npage General visibility plotting and editing command. PARAMETERS ---------- nplots - (Optional) Default=0 (All baselines to each station). The number of baselines to be displayed per page. This may be changed interactively. Since only the baselines of one station are displayed on one page, the maximum number of plots per page at a given time is 1 less than the number of stations in the sub-array being displayed. reftel - (Optional) Default="" A baseline specification or the form [sub-array-index:][antenna_name_1][ antenna_name_2] On interactive devices this specifies which baseline should be plotted first. On non-interactive devices it specifies the range of baselines to be plotted. For instance on a non-interactive device "1:" means plot all baselines of sub-array 1, whereas on an interactive device, it means, start plotting baselines for the first available antenna of sub-array 1. For further details of baseline specifications, read the antenna_names help topic. IF_index - (Optional) Default = The first sampled IF. The index of the IF to start plotting visibilities from. npage - (Optional) Default = 0 (with requests no page limit). The maximum number of pages to plot when plotting to a non-interactive device. CONFIGURATION VARIABLES ----------------------- vflags - This is a string variable that over-rides the default display attributes. It is particularly useful when displaying to a hard-copy device, where interactive changes to the default attributes can not be made. By default vflags="". In this case vplot substitutes the equivalent of vflags="efmb3". When vflags is not "", all toggled attributes are initially set to off, and the contents of the vflags string determine which of the attributes get turned back on. The entries in the vflags string are the keys used in interactive mode to toggle the respective attributes on and off, and are interpretted exactly as though you had pressed them interactively. This means that if an option appears twice in vflags the second instance cancels the first! The available keys are listed further below. For example after typing: vflags="efm1" Subsequent use of vplot after typing this will initially plot visibilities with error-bars (e), will show flagged-data (f), will show the model (m), and only display amplitudes (1). CONTEXT ------- This command can be used in non-interactive mode to display visibility data on a hard-copy device, or interactively to examine and/or edit visibilities. When displayed, flagged data appear as red '+' symbols, un-flagged data as green points and the model as a continuous light-blue line. In addition, if a visibility is flagged by a selfcal correction flag, but not by a normal visibility flag, it is displayed as a blue 'x' symbol. Only visibilities from a single IF are displayed at one time, but the selected IF can be changed interactively, or preset on the command line. HARD COPY MODE -------------- If this command is invoked when the PGPLOT output device is a hard-copy device, such as a laser printer, one can specify which baselines to plot and how to arrange them. This is illustrated in the following examples: 1. Plot all of the baselines in the observation, grouped by telescope name and sub-array, displaying 5 baselines per page. This could take some time so be prepared to wait. 0> vplot 5 2. Plot all baselines from sub-array 1, at 5 baselines per page. 0> vplot 5, 1 3. Plot all HSTK baselines of sub-array 2 in IF 3, again at 5 baselines per page. 0> vplot 5, 2:HSTK, 3 4. Plot all HSTK baselines of sub-array 2, starting from baseline HSTK-BONN, using as many plots per page as there are telescopes in sub-array 2 (minus 1). 0> vplot 0, 2:hstk bonn INTERACTIVE MODE ---------------- If the display device has a cursor, then an interactive session will be invoked. In this mode, one page of baselines is initially plotted and mouse-keys and keyboard keys are used to guide the task through plotting and data editing. Once vplot has been invoked, move the cursor into the display window and press the 'H' key on your keyboard. Whenever this is pressed during the vplot session a list of key bindings will be displayed in the terminal window from which vplot was invoked. Most keys are case-insensitive, such that both 'H' and 'h' have the same effect. On standard PGPLOT conforming devices with a mouse or other cursor control device, mouse buttons are treated as equivalent to the following keyboard keys: Left button = 'A' (This is the normal key for selecting positions). Middle button = 'D' (This is used to cancel incomplete select ranges). Right button = 'X' (Use this to exit vplot). Note that on a windowing system, the cursor must be within the display window before pressing keyboard keys (and mouse buttons) will be noticed. However, after pressing a key that needs more complex answers, such as the entry of the number of baselines to display or the entry of a telescope name, the cursor should be moved to the original text window where a prompt will be displayed to guide your entry. MOVING ABOUT BETWEEN BASELINES ------------------------------ n - (Lower-case n) Display next set of baselines p - (Lower-case p) Display preceding set of baselines Pressing 'n' in vplot causes the Next set of baselines of the current telescope to be displayed from the current sub-array. Once all baselines to that telescope have been displayed, pressing 'n' will proceed to display those of the next telescope in the observation. Once all telescopes have been displayed in this manner, pressing 'n' will display start to display baselines from the next sub-array. So by repeatedly pressing 'n' you will see all baselines in every sub-array of the observation. The 'p' key works identically but shows the Previous set of baselines. N - (Upper-case n) Display baselines from the next sub-array. P - (Upper-case p) Display baselines from the previous sub-array. Upper-case 'N' and 'P' provide a means to jump to the next or previous sub-arrays without having to view all of the intermediate baselines. T - Specify reference telescope from the keyboard (text screen) To move to another telescope without having to wade through all the baselines of previous telescopes in the observation, press 'T'. Back on the text screen you will be prompted for the name of the telescope. The name entered may be any unambiguous abbreviation of the full telescope name. eg BOLOGNA and BONN are ambiguous up to BO. BOL or BON are the shortest names that could be used to refer to them. A optional second telescope name may also be entered on the same input line, separated from the first by spaces or a hyphen, in which case the combination of the two telescope names will be used to designate the first baseline to be displayed to the new reference telescope. If the required telescope(s) are from a different sub-array than the one currently being displayed, then specify the sub-array number preceding the first telescope name and separated from it with a colon. Thus BONN-BOL selects baseline BONN-BOLOGNA in the currently displayed sub-array, while 3:BONN-BOL selects baseline BONN-BOLOGNA in sub-array 3. MOVING BETWEEN IFs ------------------ Visibilities are only displayed from one IF at a time. The identity of this IF is displayed above the collection of plots. To move onto the next or previous IF in which any channels were selected with the 'select' command, use the following keys: ] - Move to the next sampled IF. [ - Move to the previous sampled IF. The title above the plots will change to indicate which IF is being displayed. CHANGING HOW BASELINES ARE DISPLAYED ------------------------------------ The following keys toggle attributes on or off. The display will not be re-plotted immediately whenever one of these is toggled, so you can press a sequence of toggle keys before re-displaying with the new attributes. When the sequence is complete, simply press any key that is not in the list below, such as the RETURN key and the display will be updated with the new attributes. M - Toggle display of model visibilities F - Toggle display of flagged visibilities E - Toggle display of error bars 1 - Plot only amplitudes. 2 - Plot only phases. 3 - Plot both amplitudes and phases. B - Toggle breaking the plot into scans (where present) V - Toggle inclusion of flagged data in auto-scaling NB. By default, a scan is taken to be any set of integrations which is separated by more than an hour from its nearest neighbors. This can be changed with the 'scangap' command. CHANGING THE NUMBER OF BASELINES DISPLAYED ------------------------------------------ S - Select number of sub-plots per page To change the number of baselines displayed, press the 'S' key. You will be prompted for a number on the text screen. The first baseline plotted will be the same as before, but only the requested number will follow. CHANGING THE DISPLAYED UT RANGE ------------------------------- U - select UT range to be displayed (hit U twice for full range) Press 'U' to request a change in the displayed UT range. You will then be expected either to press 'U' again to display the whole UT range, or to move the cursor to the start UT of the required range and press 'A' (left mouse button), then move the cursor to the end UT of the required range and press 'A' again. The plot will then be re-displayed over the new range and all subsequent plots will be displayed over this range. At any point before the UT range selection has been completed, pressing the 'D' key (middle mouse button) will quietly abort the selection. CHANGING THE DISPLAYED AMPLITUDE OR PHASE RANGE ----------------------------------------------- Z - Select amplitude or phase range to be displayed. Press 'Z' to zoom in on a selected amplitude or phase range. You should then either to press 'Z' again to revert to the default range, or move the cursor to the first (top or bottom) amplitude or phase value of the required vertical range and press 'A' (left mouse button), then move the cursor up or down to the end of the required range and press 'A' again. The plot will then be re-displayed over the new range and all subsequent plots will be displayed over this range. At any point before the selection has been completed, pressing the 'D' key (middle mouse button) will quietly abort the selection. CHANGING WHETHER REDUNDANT BASELINES ARE DISPLAYED -------------------------------------------------- By default, for each reference telescope that it plots, vplot displays all of the baselines that include that telescope. This is recommended because it aids in finding telescope dependent errors. However, it does result in you seeing each baseline twice if you step through all antennas. This can be annoying if you have a very large number of baselines. For this reason vplot also provides the option to only show each baseline once, by only showing baselines in which the second antenna of the baseline comes later in the antenna listing than the reference antenna. Thus for the first antenna you see all of the baselines for that antenna, but for the second you see one less baseline, and so on, until by the time you reach the last antenna, there are no baselines to be plotted. O - Toggle telescope ordering to only show non-redundant baselines. EDITING DATA ------------ There are two main modes for editing and it is important to select the right one before proceeding. Station based edits flag or un-flag the selected visibilities on ALL baselines that include the current reference telescope. If you have more than one baseline displayed at a time, then this will be evident, as the selected visibilities will change color on all the displayed baselines. Baseline based editing only affects the baseline in which the selection was made. - (SPACE BAR) Toggles station based vs. baseline based editing. The current editing mode is displayed above the plots on the right-hand side of the display and can be toggled by pressing the SPACE-BAR. It is also possible to further specify the scope of edits. I - Toggle IF editing scope. W - Toggle spectral-line editing scope. By default, edits are applied to all polarizations, spectral-line channels and IFs related to the selected visibility. To specify that edits only be applied to the displayed IF, press the 'I' key. To specify that edits be only applied to the channels that were specified with the 'select' command, press the 'W' key. The mode line above the collection of plots, describes which of these editing modes is in effect. A - Flag or unflag the nearest visibility to the cursor. (Left mouse button) Pressing 'A' on the keyboard or the left mouse button near a displayed visibility point causes the status of that visibility to be toggled from un-flagged to flagged or vice versa. If flagged data are displayed, then toggling an un-flagged visibility will produce a red cross signifying its new flagged status. Otherwise the point will magically disappear, but can be seen subsequently if the display of flagged data is enabled. C - Flag all data inside select box R - Restore data inside select box If you wish to flag or un-flag an extended region of data, point by point editing is tedious. The Clip and Restore keys, 'C 'and 'R' enable you to edit all points inside a square box selected with the cursor. To use this facility, press the respective key and then move the cursor to one corner of the required region and press 'A' (left mouse button). Then move the cursor to the opposite corner of the required region and again press 'A'. The selected points will be re-displayed with their changed statuses. Note that it is especially important to know whether station or baseline based editing is required before doing this since in station based editing restoring a region that you have just clipped may restore points on related baselines that were originally clipped for other reasons. FLAGGING A WHOLE SCAN --------------------- To flag a whole scan on a given baseline, move the cursor into the selected scan on the baseline to be edited and press the 'Z' (ie. zap) key. All points on that baseline within the scan will be flagged, even those not in the currently displayed UT range. In this context a scan is either a single scan obtained after using the 'B' (break-into-scans) key, or the whole UT time range otherwise. Note that the current station/baseline editing mode has no effect on the behavior of this command - so only one baseline will be flagged at a time. ENDING A vplot SESSION ---------------------- To end a vplot session, press 'X' or the right mouse button. If substantial editing was performed in vplot then it is advisable to use the wmerge command to save the modified file before continuing to map the data. MISCELLANEOUS features ---------------------- The following interactive key bindings have not bee discussed above. L - When you press this key the current plot is re-displayed. + - This key toggles whether the cursor is shown as a small cross or as a cross-hair that extends the full width and height of the display. Currently only the /xserve and /xwindow PGPLOT devices support this feature. RELATED COMMANDS ---------------- scangap - Change the time gap used to delimit neighboring scans. radplot - Display visibility amplitude vs. UV radius. projplot - Display visibility amplitude/phase vs. projected UV distance. uvplot - Display the sampling of the UV plane. tplot - Display the time-sampling of each telescope. corplot - Display accumulated self-calibration corrections. cpplot - Display observed and model closure phases interactively.