; HLPTVFLG ;--------------------------------------------------------------- ;! Interactive time-baseline visibility Editor - internal help ;# TASK UV CALIBRATION INTERACTIVE TV-APPL ;----------------------------------------------------------------------- ;; Copyright (C) 1995-1996, 2000, 2004, 2009-2011 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- C----------------------------------------------------------------------- OFFZOOM This option resets any zoom factors and zoom center. The image is actually shown in zoom only during flagging operations (where zoom may help you point more accurately), during the setting of the zoom and of the black-and-white or color enhancements, and during image loading. C----------------------------------------------------------------------- OFFTRANS This option turns of any black-and-white enhancements done in TVFIDDLE or TVTRANSF. Has no affect if the image is in color. C----------------------------------------------------------------------- OFFCOLOR This options turns of any color enhancements done in TVFIDDLE or TVPSEUDO. Has no effect if the image is in black and white. C----------------------------------------------------------------------- TVFIDDLE This option allows you to set the zoom factor and center to blow up the data plot for more accurate cursor positioning. It also allows you to alter the look-up-tables. Button A selects image enhancement, altering between black-and-white and the AIPS-standard color contours. Button B increments the zoom or resumes zoom-center mode, while button C decrements the zoom or resumes zoom-center mode. Button D ends the enhancing and returns to the menu. Instructions appear on the terminal. C----------------------------------------------------------------------- TVTRANSF This option allows you to set the black-and-white transfer function using the TV cursor to control intercept and slope. Buttons A and B turn a plot of the LUT on and off, button C reverses the sign of the slope, and button D ends the enhancement and returns to the menu. Instructions appear on the terminal. C----------------------------------------------------------------------- TVPSEUDO This option allows you to set the color transfer function using the TV cursor. Button A loops through all possible RGB triangles, button B selects a circle in hue (which is very useful for phase displays), button C selects several color contours, and button D ends the enhancement and returns to the menu. As in AIPS, the TV cursor is used to adjust the colors within the selected function. Instructions appear on the terminal. C----------------------------------------------------------------------- DO WEDGE ? This option switches between displaying and not displaying an intensity step wedge on the TV below the data display. The wedge can help you adjust and understand the black-and-white or color transfer function. C----------------------------------------------------------------------- DO LABEL ? This option switches between displaying and not displaying axis labels on the time and baseline axes. If a wedge is displayed, the baseline axis label is replaced with labels on the intensity wedge. C----------------------------------------------------------------------- LOAD LOG This option is displayed when the amplitude transfer function is LINear and allows you to request a LOG transfer function instead. The available functions are in order LINear, LOG, SQRT, and LOG2 (a more extreme log) and may be requested cyclically. The image is immediately reloaded with the new transfer function. C----------------------------------------------------------------------- LOAD SQRT This option is displayed when the amplitude transfer function is LOG and allows you to request a SQRT transfer function instead. The available functions are in order LINear, LOG, SQRT, and LOG2 (a more extreme log) and may be requested cyclically. The image is immediately reloaded with the new transfer function. C----------------------------------------------------------------------- LOAD LOG2 This option is displayed when the amplitude transfer function is SQRT and allows you to request a LOG2 transfer function instead. The available functions are in order LINear, LOG, SQRT, and LOG2 (a more extreme log) and may be requested cyclically. The image is immediately reloaded with the new transfer function. C----------------------------------------------------------------------- LOAD LIN This option is displayed when the amplitude transfer function is LOG2 and allows you to request a LINear transfer function instead. The available functions are in order LINear, LOG, SQRT, and LOG2 (a more extreme log) and may be requested cyclically. The image is immediately reloaded with the new transfer function. C----------------------------------------------------------------------- LIST FLAGS This option allows you to list the flagging commands you have already prepared. You are prompted for a range of flag numbers to list. The selected flags are listed on your terminal. Each is labeled by a "flag" number which may be used to specify any flags that you may wish to undo. C----------------------------------------------------------------------- UNDO FLAGS This option allows you to undo any one or more of the current flagging commands. You will be asked repetitively to enter the number of the flagging command to be excised (use LIST FLAGS to determine this). Enter 0 to terminate the list. The flag commands will be deleted from the FC table and the master grid and then the data are reloaded on the display. C----------------------------------------------------------------------- REDO FLAGS This option allows you to make certain that the current flag commands are correctly applied to the master grid. Each cell of the master grid keeps track only of the first flag command which deletes it. When UNDO FLAGS is used on flag commands other than the last, cells which were undone, but should have been deleted by later commands, will not be correctly marked. This option lets you bring things back into accord by reapplying all flags (after the first undone one) to the master grid. C----------------------------------------------------------------------- SET REASON This option allows you to customize the reasons written to the FG table for the flagging commands that you prepare with TVFLG. The default is to insert a string stating the date and time at which TVFLG actually modifies the FG table. This option allows the user to build up a list of up to 9 customized reasons. All flagging commands prepared after a particular reason is selected will have that reason attached to them when they are written to the FG table. Each reason can have a maximum of 24 characters in length. Reason 1 starts as the default reason string and cannot be changed. C----------------------------------------------------------------------- ENTER BLC This option lets you type on the terminal the bottom left corner pixels numbers of the portion of the master grid which you wish displayed. In general, the master grid has more baselines in X or times in Y than will fit on a single TV picture. The actual displayed picture is then shortened by time averaging and by selecting bottom left and top right corners. The prompt on the terminal will indicate the legal range of values. When TVFLG starts it chooses a display averaging time to fit all the rows on the TV and does every n'th pixel, if needed, to fit all columns on the TV. Later it will display whatever portion of BLC to TRC fits in the Y direction, but will subsection X if needed. It is wise to avoid that sub-sectioning with suitable corners. The SET WINDOW+LOAD option allows you to set the image corners with the TV cursor. The status display at the bottom of the screen show the corners of the currently loaded image with an asterisk after any value which will change on the next LOAD. C----------------------------------------------------------------------- ENTER TRC This option lets you type on the terminal the top right corner pixels numbers of the portion of the master grid which you wish displayed. In general, the master grid has more baselines in X or times in Y than will fit on a single TV picture. The actual displayed picture is then shortened by time averaging and by selecting bottom left and top right corners. The prompt on the terminal will indicate the legal range of values. When TVFLG starts it chooses a display averaging time to fit all the rows on the TV and does every n'th pixel, if needed, to fit all columns on the TV. Later it will display whatever portion of BLC to TRC fits in the Y direction, but will subsection X if needed. It is wise to avoid that sub-sectioning with suitable corners. The SET WINDOW+LOAD option allows you to set the image corners with the TV cursor. The status display at the bottom of the screen show the corners of the currently loaded image with an asterisk after any value which will change on the next LOAD. C----------------------------------------------------------------------- ENTER AMP PIXRANGE This option allows you to enter on your terminal the lower and upper ranges of the amplitude to be displayed. The default is to display the full range of values. Having entered an amp range, you may return to the default by entering an amp range of 0 0. The data range and the displayed range are shown on the terminal on each LOAD. All values of amplitude (and amplitudes of the vector and scalar differences) will be clipped at the specified pixrange before display. The option takes effect on the next LOAD. C----------------------------------------------------------------------- ENTER PHS PIXRANGE This option allows you to enter on your terminal the lower and upper ranges of the phases to be displayed. The default is to display the full range of values. Having entered a phase range, you may return to the default by entering a phase range of 0 0. The data range and the displayed range are shown on the terminal on each LOAD. All values of phase (and phase difference) will be clipped at the specified pixrange before display. The option takes effect on the next LOAD. C----------------------------------------------------------------------- ENTER RMS PIXRANGE This option allows you to enter on your terminal the lower and upper ranges of the vector and scalar RMSes to be displayed. The default is to display the full range of values. Having entered an RMS range, you may return to the default by entering an RMS range of 0 0. The data range and the displayed range are shown on the terminal on each LOAD. All values of RMS will be clipped at the specified pixrange before display. The option takes effect on the next LOAD. C----------------------------------------------------------------------- ENTER R/M PIXRANGE This option allows you to enter on your terminal the lower and upper ranges of the vector and scalar RMS/mean to be displayed. The default is to display the full range of values. Having entered an RMS/mean range, you may return to the default by entering an RMS/mean range of 0 0. The data range and the displayed range are shown on the terminal on each LOAD. All values of RMS/mean will be clipped at the specified pixrange before display. The option takes effect on the next LOAD. C----------------------------------------------------------------------- ENTER SMOOTH TIME This option allows you to enter on your terminal the number of the basic time intervals in the master grid to be averaged in the displayed data. TVFLG begins with this value set to allow all of the data to appear on the TV. You may set any integer value you like, however, and then choose the part of the data to display using other windowing options. The smooth time must be set to at least 2 of the basic time for the RMS and RMS/mean displays to work. NOTE: if you flag a displayed point that has been smoothed, then all the samples in that average are flagged. The status display at the bottom of the TV shows the average time of the current display with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- ENTER SCAN TIME This option allows you to enter on your terminal the number of the basic time intervals in the master grid to be averaged in the "rolling buffer" for the difference displays. These are displays of the difference between the data at time T and the average of the data at times near T. The scan time sets the meaning of "near" in a rolling-buffer fashion. Thus for a scan time of 30 seconds and data at 10-second intervals, the average for a set of 7 points is as follows: time average of times 00 00 10 20 10 00 10 20 20 10 20 30 30 20 30 40 40 30 40 50 50 40 50 60 60 40 50 60 TVFLG begins with this value set to 3 times the smooth time, but you may set any integer value you like greater than the smooth time. The status display at the bottom of the TV shows the scan time of the current display with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- ENTER CHANNEL If you have more than one spectral channel in your master grid, this option lets you select which one will be displayed and used in editing. If you have more than two channels, then you will be prompted for a channel number; otherwise the 2 are simply switched. If flags are to be applied to a single channel, they are applied to the channel selected with this option. As with most TVFLG options, the data are NOT loaded immediately, allowing you to make other selections before using the LOAD options. The status display at the bottom of the TV shows the channel of the current display with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- ENTER IF If you have more than one IF in your master file, this option lets you select which one will be displayed and used in editing. If there are more than 2 IFs, you will be prompted for an IF number. Otherwise, the IF is simply switched. If flags are to be applied to a single IF, they are applied to the IF selected with this option. The data are NOT immediately reloaded, allowing you to make other selections before using the LOAD options. The status display at the bottom of the TV shows the IF of the current display with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- ENTER STOKES FLAG This option lets you specify which polarizations are to be flagged by the following flag commands. You will be prompted for a Stokes string or flag mask, i.e., 1111 will flag all four Stokes parameters, 1001 will flag RR and LR. The status line on the bottom of the TV reflects the current value of this option. NOTE: this string/mask applies to the displayed Stokes type which may or may not be the same as the input data set. There are three types recognized: RR/LL/RL/LR, I/Q/U/V, and (sort of) XX/YY/XY/YX where the mask refers to these polarizations in this order. Thus, 0100 would flag LL even if the master grid consisted solely of RL data. C----------------------------------------------------------------------- SWITCH SOURCE FLAG This option lets you toggle between having the following flag commands apply to all sources and having them apply only to to the source of the displayed data. The status line on the bottom of the TV reflects the current value of this option. This affects flagging of time ranges primarily, and determines whether all sources in the range or only those actually displayed by TVFLG are to be flagged. C----------------------------------------------------------------------- SWITCH ALL-CH FLAG This option lets you toggle between having the following flag commands apply to all spectral channels and having them apply only to the current spectral channel. The status line on the bottom of the TV reflects the current value of this option. C----------------------------------------------------------------------- SWITCH ALL-IF FLAG This option lets you toggle between having the following flag commands apply to all IFs and having them apply only to the current IF. The status line on the bottom of the TV screen reflects the current value of this option. C----------------------------------------------------------------------- DISPLAY AMPLITUDE This option specifies that fringe amplitudes are to be smoothed from the master grid, displayed on the TV, and used in the editing. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY PHASE This option specifies that fringe phases are to be smoothed from the master grid, displayed on the TV, and used in the editing. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY RMS This option specifies that RMSes of the fringe amplitudes over the smoothing interval are to be computed from the master grid, displayed on the TV, and used in the editing. Note that this uses scalar amplitudes which do not have a Gaussian distribution, but which are not sensitive to phase variations which might be fixed by self-cal. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY RMS/MEAN This option specifies that ratios of the RMS of the fringe amplitudes over the smoothing interval to their mean are to be computed from the master grid, displayed on the TV, and used in the editing. This uses scalar amplitudes which are not sensitive to phase variations (which might be correctable with self-cal), but which have a non-Gaussian, biased distribution. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY VECT RMS This option specifies that vector RMS of the fringe amplitudes over the smoothing interval are to be computed from the master grid, displayed on the TV, and used in the editing. The vector RMS is found by summing the RMS of the real and imaginary parts of the visibility in quadrature. It is quite sensitive to phase variations, but has Gaussian statistics. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY VRMS/VAVG This option specifies that ratios of the vector RMS of the fringe amplitudes over the smoothing interval to their vector average are to be computed from the master grid, displayed on the TV, and used in the editing. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY AMP V DIFF This option specifies that the amplitude of the vector difference between the (possibly-smoothed) fringe visibility at time T and the vector average of the visibilities in the "scan" interval surrounding T is to be computed as a function of T from the master grid, displayed on the TV, and used in the editing. This option is a very powerful detector of jumps in either phase or amplitude. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY AMPL DIFF This option specifies that the absolute value of the difference between the (possibly-smoothed) fringe amplitude at time T and the scalar average of the amplitudes in the "scan" interval surrounding T is to be computed as a function of T from the master grid, displayed on the TV, and used in the editing. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY PHASE DIFF This option specifies that the absolute value of the difference between the (possibly-smoothed) fringe phase at time T and phase of the vector average of the visibilities in the "scan" interval surrounding T is to be computed as a function of T from the master grid, displayed on the TV, and used in the editing. The screen is not updated immediately, allowing you to select other options before using the LOAD options. The status line at the bottom of the TV shows the type of data currently displayed with an asterisk appended if it will change on the next LOAD. C----------------------------------------------------------------------- DISPLAY STOKES xx If you have more than one Stokes or polarization in your master grid (i.e. I/V or Q/U or RR/LL or RL/LR), this option lets you select Stokes "xx" to be displayed and used in in editing. The data are NOT immediately reloaded, allowing you to make other selections before using the LOAD options. The status line at the bottom of the TV shows the Stokes of the data currently displayed with an asterisk appended if it will change on the next LOAD. The menu shows the xx which would change the current choice for the next LOAD. Thus, if RR is displayed and you have selected LL but not yet LOADed it, the menu will show RR again and the status line will show RR*. C----------------------------------------------------------------------- SORT BY BASELINE SORT BY LENGTH If your data set has an antennas file, this option allows you to choose the ordering of the X (baseline) axis, either BASELINE "number" or approximate baseline length order (where antenna locations are used ignoring time-variable projections). Baseline number is either the "normal" baseline number sequence (1-1, 1-2, 1-3, ... 1-N, 2-2, 2-3, ...) or the "antenna-pair" sequence in which baseline 1-2 is repeated as baseline 2-1. The choice between these is made when the master file is built through adverb DPARM(3) > 0 => the antenna pair choice. When SORT BY BASELINE is displayed, the data are currently sorted by length (or will be on the next LOAD) and when SORT BY LENGTH is displayed, the data are currently sorted by number (or will be on the next LOAD). The status line at the bottom of the TV show the order of the data currently displayed with an asterisk appended if it will change on the next LOAD. Thus, if the menu shows LENGTH again and the status line shows LENGTH*, you have selected BASELINE, but not yet LOADed it. C----------------------------------------------------------------------- OFF WINDOW + LOAD This option will reset the image corners to display the full image - or at least to try - and then reload the TV screen. This is one of the 6 LOAD options which force an update of the TV display to reflect the numerous possible choices of parameters (Stokes, IF, scaling, baseline order, smooth and scan times, channel, display type) which may have been changed since the last LOAD. C----------------------------------------------------------------------- SET WINDOW + LOAD This option lets you reset the image corners with the TV cursor and then reloads the TV screen. Move the cursor to the desired bottom left corner; the lines will follow the cursor. Hit any button to set the BLC and switch to setting the TRC. The lines will now show your selected window. Hit buttons A or B to reset the other corner or buttons C or D to complete the window selection and load the data to the TV. This is one of the 6 LOAD options which force an update of the TV display to reflect the numerous possible choices of parameters (Stokes, IF, scaling, baseline order, smooth and scan times, channel, display type) which may have been changed since the last LOAD. C----------------------------------------------------------------------- LOAD NEXT IF/ST This option first increments the current IF by 1 leaving the current spectral channel unchanged. If the IF exceeds the maximum, it resets the IF number to the beginning (BIF) and switches the polarization. If the Stokes flag is NORR (0111) it is changed to NOLL (1011) and vice versa. Then the TV screen is reloaded. This is one of the 6 LOAD options which force an update of the TV display to reflect the numerous possible choices of parameters (Stokes, IF, scaling, baseline order, smooth and scan times, channel, display type) which may have been changed since the last LOAD. C----------------------------------------------------------------------- LOAD NEXT CHAN This option increments the current spectral channel by 1 and if that exceeds the maximum it sets it to the minimum. Then the TV screen is reloaded. This is one of the 6 LOAD options which force an update of the TV display to reflect the numerous possible choices of parameters (Stokes, IF, scaling, baseline order, smooth and scan times, channel, display type) which may have been changed since the last LOAD. C----------------------------------------------------------------------- LOAD PREV CHAN This option deccrements the current spectral channel by 1 and if that exceeds the minimum it sets it to the maximum. Then the TV screen is reloaded. This is one of the 6 LOAD options which force an update of the TV display to reflect the numerous possible choices of parameters (Stokes, IF, scaling, baseline order, smooth and scan times, channel, display type) which may have been changed since the last LOAD. C----------------------------------------------------------------------- LOAD This option will reload the TV screen. This is one of the 6 LOAD options which force an update of the TV display to reflect the numerous possible choices of parameters (Stokes, IF, scaling, baseline order, smooth and scan times, channel, display type) which may have been changed since the last LOAD. C----------------------------------------------------------------------- FLAG PIXEL This option allows you to flag (delete) data points one at a time. Move the cursor to the desired datum; the source name, time, baseline, and flux under the cursor are displayed on the upper left of the TV screen. Press button A or B to flag a point and loop for more, press button C to flag a point and return to the menu, and press button D to return to the menu with no further flagging. C----------------------------------------------------------------------- FLAG/CONFIRM This option allows you to flag (delete) data points one at a time. Move the cursor to the desired datum; the source name, time, baseline, and flux under the cursor are displayed on the upper left of the TV screen. Press button A or B to flag a point and loop for more, press button C to flag a point and return to the menu, and press button D to return to the menu with no further flagging. You are prompted on the terminal to confirm each flagged point; answer Y or N. This option is the same as FLAG PIXEL except for the very conservative need to confirm each point. C----------------------------------------------------------------------- FLAG AREA This option allows you to flag (delete) data in a range of time and a range of baseline number. Move the cursor to the lower-left corner of the area you wish to flag (the box will follow the cursor). Once at the desired point, hit button A to mark it. Then move the cursor to the upper-right corner of the desired area. Hit button A to reset the other corner, hit button B to flag the data inside the box and loop to set another box, or hit button C to flag the data and return to the menu, or hit button D to return to the menu with no further flagging. C----------------------------------------------------------------------- FLAG TIME RANGE This option allows you to flag (delete) a range of times for all baselines. Move the cursor to the start time of the range you wish to flag. The horizontal line will follow while the source, time, and flux of the point under the cursor will be displayed in the top left corner of the TV. Hit button A to set the start time and a second horizontal line will appear 10 pixels above. Move the cursor to the end point of the desired time range; the second line will follow. Hit button A to switch between the begin and end times; hit button B to flag the data in the specified range and loop to set another time range; hit button C to flag the data and return to the menu; or hit button D to return to the menu with no further flagging. C----------------------------------------------------------------------- FLAG ANTENNA-DT This option allows you to flag (delete) a range of times for all baselines to a specified antenna. This option prompts you to enter on the terminal the antenna and sub-array number to be flagged. A Q or other non-numeric input at this stage causes the option to return to the menu. Then move the cursor to the start time of the range you wish to flag. The horizontal line will follow while the source, time, and flux of the point under the cursor will be displayed in the top left corner of the TV. Hit button A to set the start time and a second horizontal line will appear 10 pixels above. Move the cursor to the end point of the desired time range; The second line will follow. Hit button A to switch between the begin and end times; hit button B to flag the data in the specified range and loop to set another antenna, sub-array, and time range; hit button C to flag the data and return to the menu; or hit button D to return to the menu with no further flagging. C----------------------------------------------------------------------- FLAG A TIME This option allows you to flag (delete) the data for all baselines at a specific time. Move the cursor to the time you wish to flag. The horizontal line will follow it while the source, time, and flux of the point under the cursor will be displayed in the top left corner of the TV. Once on the desired time, hit button A or B to flag that time and loop for more, hit button C to flag the time and return to the menu, and hit button D to return to the menu with no further flagging. C----------------------------------------------------------------------- FLAG BASELINE This option allows you to flag (delete) the data for all times at a specific baseline. Move the cursor to the baseline you wish to flag. The vertical line will follow it while the source, time, and flux of the point under the cursor will be displayed in the top left corner of the TV. Once on the desired baseline, hit button A or B to flag that baseline and loop for more, hit button C to flag the time and return to the menu, and hit button D to return to the menu with no further flagging. C----------------------------------------------------------------------- FLAG BASELINE-DT This option allows you to flag (delete) the data for a range of times at a specific baseline. Move the cursor to the baseline you wish to flag. The backward L will follow it while the source, time, and flux of the point under the cursor will be displayed in the top left corner of the TV. Once on the desired baseline and start time, hit button A, B, or C to switch to setting the stop time (and altering the chosen baseline). Subsequent hits of button A switch between setting of the start and the stop times. Hit button B to flag this antenna-DT and go on to another one, button C to flag this antenna-DT and return to the main menu, or hit button D to return to the menu with no further flagging. C----------------------------------------------------------------------- CLIP BY SET #S This option allows you to flag (delete) all data outside a range of values (in the displayed parameter) which you specify on the terminal. N.B.: this option uses the values in the displayed type, e.g. the RMS/mean, to set the flags. C----------------------------------------------------------------------- CLIP INTERACTIV This option allows you to flag (delete) all data outside a range of values (in the displayed parameter) which you specify interactively. N.B.: this option uses the values in the displayed type, e.g. the RMS/mean, to set the flags. Move the TV cursor horizontally to set the upper clip limit. The current clip limits will be displayed in the upper left corner of the TV and the clipped data will seem to disappear. Hit button A or B to switch between upper and lower clip limits (except for RMS's), hit button C to flag the data and return to the menu, or hit button D to return to the menu with no flagging. C----------------------------------------------------------------------- CLIP BY FORM This option allows you to flag (delete) data over a range of channels, IFs, and Stokes using the "method" and clipping range of some previous clip operation. In the other CLIP options, one can use the data of one channel, IF, and Stokes to flag other channels, IFs, and/or Stokes using the ALL-CH, ALL-IF, and STOKES FLAG options. This option allows you to use the data of each channel, IF, and Stokes in turn over a specified range of channels, IFs, and Stokes, to delete bad data. You are prompted to enter on the terminal the number of a previous clip operation (use LIST FLAGS) to use as a pattern. i.e., to specify the display parameter type, the averaging and scan intervals, the clip levels, the window on the data, and even the ALL-CH, ALL-IF, and Stokes flags. You will be prompted to enter on the terminal the desired range of channels, IFs, and/or Stokes unless the pattern operation applied its flags to all channels, IFs, and/or Stokes. The full range is used in those cases. C----------------------------------------------------------------------- EXIT This option is used to exit the program. If you have done any flagging, you will be asked if you want to apply the flags to the input data set. If you answer N and the master grid is cataloged (DOCAT > 0), then the program exits and and you may resume TVFLG at a later time using the master grid (IN2SEQ) with no loss of information. If you answer N and the master grid is not cataloged, then you will be reminded of this and if you still answer N, then the master grid is deleted and your flagging is discarded. If you answer Y - which you should do only when you are done with the current selection of data - then TVFLG writes your flagging commands into an FG table for a multi-source file, or applies them directly to the data for a single-source file. The master grid is then changed to make all current flagging permanent, or deleted if it is not cataloged. C-----------------------------------------------------------------------