When this program is run, each baseline is displayed, one at a time, with the x-axis representing channel number (increasing to the right), the y-axis representing the change in time (increasing upward), and the color intensity representing the amplitude or phase (depending on the value of the keyword ``mode'') of the visibility. The current antenna that constitute the baseline are labeled at the bottom of the plot (if room permits). In addition, if room permits, a color wedge is displayed to the right side of the visibility data and is the sum of the data over all displayed channels. Also, a wedge of the sum of the data over all displayed times will appear above (or below) the data as room permits.
The user may edit the data in one of two ways: 1) By entering commands at the keyboard; or 2) by selecting commands from the listed menu items. Which method is determined by the presence of a menu program (such as ``XPANEL'' for the Sun systems).
If no menu program is currently active, then a message is issued to the user and all commands are prompted from the keyboard. Commands are entered followed by a carriage return (<CR>). Single letter abbreviations are used for all commands. The current command list, each corresponding abbreviation, and a brief description of each command is available by entering a question mark (``?'') as a command. Commands requiring further interaction (eg. ``select'' and ``value'') will prompt the user when they are invoked.
If a menu program is active, then TVCLIP will attempt to construct an assortment of menu buttons and other items that will perform the equivalent of entering commands at the keyboard. Certain commands (eg. ``select'' and ``value'') require further cursor input and will prompt the user for a particular action (for example: ``select'' will request the user to select the region to box for further flagging commands).
The current technique of editing is to load the baseline to be edited, zoom and pan to the desired location, and then, select the region to be edited followed by an editing command. To identify a region to edit, chose the ``select'' command (or ``channel'' or ``time'' select options) and then use the cursor to box the desired points. To select a desired region, move the cursor (mouse) to a corner of the region to select; identify, to the program, the corner (usually by pushing and holding the left mouse button); move the pointer to the other corner (by dragging the mouse), and then identify, again to the program, the other corner (usually by releasing the left mouse button). After the region to edit has been identified, the selected region may be flagged as good or bad using the appropriate editting command (or button). If data is flagged improperly, the ``undo'' command will reverse the last editing operation.
NOTE: If the device does not support this type of ``rubber- band'' selection (Eg. XMTV does; MXAS does not), then the user will be asked to use the cursor to identify two opposite corners to delimit the selected region.
To save the editing done to a particular baseline, use the ``exit'' command (or select the ``exit'' button). The flagging changes will be immediately applied to the data. To NOT save the changes made to a particular baseline, use the ``quit'' command (or button). After a ``quit'' or ``exit'' operation, the data for the next baseline is loaded onto the display and the user may continue editing. Selecting the ``abort'' command (button) at any time will perform the same operation as ``quit'', but will also terminate the program.
You can use the 'batch-mode' of tvclip if you have a lot of similar flagging to do. Use tvclip in interactive mode to determine a good clip level and a sequence of DIFF and CLIP commands that is appropriate for your data. Then set the clip level and enter the commands in the 'commands' keyword. You can then either watch the automatic flagging on the tv, or switch off the display (options=notv) to speed things up.
The first form causes a connection to be made with a network display server, whereas the second form uses local hardware directly. For the network servers, the server process may have to be started before invoking the Miriad task -- see below.
Currently supported types are:
xmtv Miriad X server. `server' is the servers hostname. (use "localhost" if you are not networked) Normally the xmtv server will be the same host as the X server. The user will normally invoke the xmtv server before running any Miriad TV tasks, with
If the X server and xmtv server are on different hosts, you may need to set the DISPLAY environment variable on the xmtv server, and use xhost on the X server.
ivas IVAS (VMS only). `device' is the VMS device name. You will require an IIS IVAS for this.
ivserver IVAS server. `server' is the servers hostname. Servers are currently installed on castor.astro.uiuc.edu and bkyast.berkeley.edu.
msss Miriad Sun Screen server. `server' is the serving Sun, which can be any Sun with a console. The user will normally invoke the server before running any Miriad TV tasks, with
mxas Miriad X server. `server' is the servers hostname. This is an inferior server to xmtv.
A uv data-set can have correlations from either (or both) a spectral or a wideband (continuum) correlator. Both the spectral and wideband correlators produce multiple correlations (channels). The string part of the line parameter is used to select the spectral or wideband channels. It may be one of:
"channel" Spectral channels. "wide" Wideband (continuum) channels. "velocity" Spectral channels, resampled at equal increments in velocity (using the radio definition). The resampling involves a weighted average of the spectral channels. This is useful if the source was not Doppler tracked correctly. "felocity" Similar to "velocity", except that the parameters are given using the optical velocity definition.Generally the default is "channel" if the data-set has spectral channel data, and "wide" otherwise.
The four numbers that accompany the string give:
nchan, start, width, step
These four numbers specify which channels to select from the input dataset and how to combine them to produce the output channels that the Miriad task will work on.
nchan is the number of output channels produced. Generally it
defaults to the number of input channels.
start is the first channel from input dataset that is to be used.
It defaults to 1 (i.e. first channel).
width gives the number of input channels to average together to
produce a single output channel. It defaults to 1.
step gives the increment between selected input channels. It
defaults to the value of "width".
For "velocity" linetype, the start, width and step parameters are given in km/s. The output channels are centered on velocities: start, start+step, start+2*step, etc.
The `line' parameter interacts with the "select=window" selection for "channel" and "velocity"/"felocity" linetypes. See the help on select for more information.
selects 10 output channels, being input spectral channels 1 to 10. Similarly
selects 10 output channels, starting at input channel 8, and skipping every second input channel, whereas
selects 10 output channels, again starting at input channel 8, but each of the output channels consists of the average of two of the input channels. Finally
resamples the spectral data in velocity, to give 10 channels of width 1 km/s. The channels are centered at -10.0,-9.0,-8.0, etc, km/s. NOTE: Here ``type'' must be `channel' or ``wide'' and the maximum of both ``width'' and ``step'' must be 1. The default is to display all channels.
'nochannel', 'notime' and 'nopixel' are clip options. By default the "CLIP" command will flag channels, times and individual pixels with an rms that is too far from the median. These options allow you to exclude some forms of clipping. 'notv' display option, do not show anything on the tv. Speeds up non-interactive clipping. This can only be used if you also fill in the commands keyword. Because with 'notv' the data does not have to fit on the screen, less time averaging is needed. Usually the data will be flagged at full time resolution. 'nosrc' Do not cause a break in the display when the source changes. Normally TVFLAG puts a gap in the display whenever the source changes.
See also documentation for subroutine selprobe(), which may very well differ slightly from this document.
time(t1,t2)Select data between times t1 and t2 (UT). Times are in the format:
yymmmdd:hh:mm:ss.sVarious abbreviations are possible. If no date part is given, then the time matchs all data (regardless of its date) for the given time of day. e.g. time(03OCT30:05:41:08,03OCT30:05:43:09)
antennae(a1,a2,...)(b1,b2...)Select all baselines pairs formed between first and second list of antennas. The second list is optional and defaults to all antennas.
uvrange(uvmin,uvmax)Select visibilities with uv radius between uvmin and uvmax (in kilo wavelenghts). If only one value is given, uvmin is taken as zero.
uvnrange(uvmin,uvmax)Select visibilities with uv radius between uvmin and uvmax (in nanoseconds). If only one value is given, uvmin is taken as zero.
visibility(n1,n2)Select visibilities numbered n1 to n2 inclusive.
increment(inc)Select every inc'th visibility.
ra(r1,r2)Select visibilities whose RA is in the range r1 to r2. RAs are given in the format
hh.hhhVarious abbreviations are possible.
dec(d1,d2)Select visibilites whose DEC is in the range d1 to d2. Declinations are given in the format
dd.dddVarious abbreviations are possible.
ha(h1,h2)Selects on hour angle (values in decimal hours or hh:mm:ss)
lst(lst1,lst2)Selects on LST (values in decimal hours or hh:mm:ss)
elevation(el1,el2)Selects on elevation (values in degrees)
dra(p1,p2)Select visibilities for which the RA of the pointing center is offset from the main pointing center by between p1 and p2 arcseconds.
ddec(p1,p2)Select visibilities for which the DEC of the pointing center is offset from the main pointing center by between p1 and p2 arcseconds.
dazim(p1,p2)Select visibilities for which the DAZIM offset is between p1 and p2 arcseconds.
delev(p1,p2)Select visibilities for which the DELEV offset is between p1 and p2 arcseconds.
pointing(p1,p2)Select visibilities with the rms pointing error in the range p1 to p2 arcseconds. If only one number is given, p1 is taken as 0.
polarization(p1,p2,p3,...)Select visibilities on the basis of their polarization/Stokes parameter. p1,p2,p3,... can be selected from "i,q,u,v,xx,yy,xy,yx,rr,ll,rl,lr" Conversion between polarizations Stokes parameters (e.g. convert linears to Stokes) is not performed by this mechanism (see keyword stokes).
source(SRCNAM1,SRCNAM2,...)Select correlations from the particular source. Several sources can be given. An asterisk in the source name is treated as a wildcard. Note that the sourcename match is done IGNORING CASE.
purpose(TYPE)Select based on the intent/purpose of the observation. Introduced in CARMA, where the letters B (bandpass), F (fluxcal), G (gaincal), P (polarization), R (radio pointing), S (science) and O (other) are used. Multiple letters from this set can be chooses. No wildcards allowed.
seeing(r1,r2)Select on seeing monitor rms path length (in microns). The UV variable used is smonrms for ATCA, rmspath for CARMA
frequency(f1,f2)Select correlations, where the sky frequency of the first correlation is in the range f1 to f2 (in GHz). If only a single frequency is given, then correlations are selected if the first correlation is within 1% of the given frequency. Note this selects the whole record. This may include several spectral-windows whose frequency is quite different from the first correlation in the first window.
amplitude(amplo,amphi)Select any correlation, where the amplitude is between "amplo" and "amphi". If only one value is given, then "amphi" is assumed to be infinite.
shadow(d)Selects data that would be shadowed by an antenna of diameter "d" meters. If "d" is zero, then the actual diameter of the antennas (if known) is used. If some data is shadowed, it is advisable to use an antenna diameter value greater than the physical antenna size (e.g. 20% larger).
bin(b1,b2)Select visibilities which have pulsar bin numbers in the range b1 to b2 inclusive. If b2 is omitted, just pulsar bin b1 is selected.
on(n)This is used with single dish observations, anbd selects based whether the "on" variable in the data is on (1) or off (0).
autoThis is used with files that contain a mix of autocorrelations and crosscorrelations. This selects just the autocorrelation data.
window(w1,w2,...)Select by spectral window (IF band in AIPS terminology). See the help on window for more information.
orThe list of subcommands before and after the 'or' are "ored" together.
andDefault ??? NOTE: The default is to use all visibilities.