images(z1,z2)Select image planes z1 to z2 inclusive. z2 defaults to z1.
quarter(z1,z2)Select the inner quarter of the image planes z1 to z2 inclusive. If both z1 and z2 are missing, then all planes are selected. If only z2 is omitted, z2 defaults to z1.
boxes(xmin,ymin,xmax,ymax)(z1,z2)Select the pixels within a box with corners xmin,ymin,xmax,ymax. z1 and z2 are the same as in the "image" subcommand. If z1 and z2 are omitted, all planes are selected.
polygon(x0,y0,x1,y1,x2,y2,...)(z1,z2)Select the pixels within the polygon defined by the list of vertices. z1 and z2 are the same as in the "image" subcommand. If z1 and z2 are missing, all planes are selected. If only z2 is omitted, it defaults to z1.
mask(file)Select pixels according to the mask given in the file.
The units of the numbers given in the above commands are, in general, absolute pixels. But this can be changed (and rechanged) by using one of the following subcommands.
abspixelCoordinates are interpreted as absolute pixel values, the default.
relpixelCoordinates are relative to the reference pixel of the map.
relcenterCoordinates are relative to the central pixel of the map, (defined as (naxis1/2+1,naxis2/2+1)).
arcsecCoordinates are in arcseconds, relative to the reference pixel.
kmsCoordinates in the third dimension are in km/s. For the moment imspec only recognizes rectangular boxes. It will use the mask associated with the input image.
'mean' Plot the mean 'sum' Plot the sum 'flux' Plot the flux 'pbcflux' Plot the primary-beam-corrected flux (not yet implemented)
'tb' Convert the units of mean or sum to brightness temperature, using the input for the beam keyword
'hanning,#' Hanning smooth the data first over # pixels (must be an odd number) 'boxcar,#' Boxcar smooth the data first over # pixels 'deriv,#' Take the derivative after smoothing. If #=1 a one-sided derivative is taken, for #=2 a two-sided. Useful for Zeeman work.
'noheader' Do not write the header information, just the numbers, producing an ASCII file for a plotting program 'list' Write the spectrum to the screen/logfile 'eformat' Always use format 'e' instead of 'g' to write results 'guaranteespaces' Make sure there is always a space between columns (at the cost of precision)
'xmin,#' Give lower x-value on axis 'xmax,#' Give upper x-value on axis 'ymin,#' Give lower y-value on axis 'ymax,#' Give upper y-value on axis (for these four options the default is autoscaling) 'title,#1,#2,#3' Put the string #1 at x-position #2 and y-position #3, with positions measured in units of the coordinates on the axes. If 'title' is the last option, the title is put in the upper left hand corner. 'style,#' This selects the plot style. #=connect means connect the datapoints #=step means make one-bin wide connected horizontal line segments #=histo means bins are drawn as a horizontal line surrounded by two vertical lines
- Example 1: to get a profile along the velocity axis (a spectrum) use
axes=ra,dec, region=relpix,box(-31,-31,32,32)(10,40)to average in ra from -31 to 32, in dec from -31 to 32 and plot the average as function of velocity from channel 10 to 40. - Example 2: to get a profile along the ra axis (at a given declination) use
axes=dec,vel, region=relpix,box(-31,0,32,0)(10)to plot a profile along ra from ra=-31 to ra=32, at dec 0 and in plane 10. - Example 3: to get a set of profiles along the ra axis (at a number of declinations) use
axes=vel, region=relpix,box(-31,-31,32,32)(10)to plot a profile along ra, for plane 10, one for each declination between -31 and 32. - Example 4: to get a profile along the declination axis (at a given ra) use
axes=ra,vel, region=relpix,box(-10,-31,10,32)(10)to plot a profile along declination, with ra averaged from ra=-10 to ra=10, and in plane 10.
The default is to make a spectrum in the velocity direction (example 1). Possible values for axes are: 'rascension', 'declination', case and capitalized versions and the string 'R.A.' are also recognized. Minimal matching is applied. One or two axes may be given.
Usually there exists a default file name or device name. The part after the slash gives the plotter type. Examples of the type are:
xs X-windows output. This window is resizeable and persistent. Prepending a number allows you to use multiple windows, e.g. 1/xs, 2/xs etc. xd X-windows output. A transient window that disappears when your task exists. ps Postscript (landscape mode). vps Postscript (portrait mode). cps Color postscript (landscape mode). gif gif files. Only supported with g77, not gfortran. vcps Color postscript (portrait mode). tek Tektronix 4010 or equivalent. xterm Xterm window (better for simple plots over slow X links).
A `?' as device name generates a complete list of the recognized types (which will most likely vary from system to system).
Files created for hardcopy devices must be spooled to the printer separately. The command needed for this is site and device specific.