Selecting output and input.

 There are a few things you may have to do to ensure SPECX knows where to plot spectra and so forth. These setup commands are described below, and I recommend running through them each time you start up, especially if you have colleagues who may be working in the same area, and who may have reset some variables.

1) To select a driver for your graphics terminal, you must send the command set-terminal- device:

$\gt\!\gt$ s-t-d

If you are using a Sun workstation, such as IIWI itself, take xw, and the default device. For a VT330 answer with tek_4010, and a carriage return to indicate that you will be plotting on the current terminal. xserve will keep the Xwindows display up until you close it, whatever happens.

2) set-plot-device allows you to select the eventual intended destination of plot files. This can be a hardcopy device, such as a laser printer, but initially this will be your terminal screen:

$\gt\!\gt$ s-p-d t

3) Lastly specify the driver appropriate to your hardcopy device (this will usually be a LaserJet printer, which is what we have in at the summit, at HP and in Hilo):

$\gt\!\gt$ s-h-d

Taking the default (ps_l) will usually be what you want, at JCMT at least. ps_p re-orientates the page for portrait format. One of the advances made by SPECX6.7 is the inclusion of colour Postscript (e.g. cps_l) and GIF output (e.g. gif_l) by virtue of the upgrade to a modern version of PGPLOT. The latter are very useful for glossy publications and overheads, and Web presentations respectively.

An Aside

When SPECX reads a data file it needs to know what the filename is. In the dim past all data files were called scan_*.dat. For some long time now files have been labeled according to what backend was used in the data collection, so that data taken with the DAS is called obs_das_*.dat. SPECX6.7 assumes the latter; however if you are working with really old data you might have to tell SPECX the GSD filename prefix. There have also been occasions when users for their own reasons have renamed a file with a different prefix. It doesn't really matter what the prefix is, so long as the last part of the name has the scan number in it. For instance you could call your data files my_data_nnnn.dat. Thus for such a case you would use set-gsd-filename:

$\gt\!\gt$ s-g-f my_data_

To get at AOSC data use

$\gt\!\gt$ s-g-f obs_aosc_

or, more simply

$\gt\!\gt$ aosc

Dealing with multi-section (-sub-band) data (such as that taken with the DAS and the long-gone `Kent' correlator) is more complicated in principle, but SPECX is set up to handle it with little fuss. If you are reducing non-DAS or other data and want to revert to standard DAS data format use the command

$\gt\!\gt$ das

In fact, such a command does more than just reset the default prefix. It also sets the number of `quadrants' (up to 8!) or individual subsections in the data array. The subsections will have a discontinuous frequency scale from one to another in such a case. Thus the AOSC usually produces only one `quadrant', while a DAS spectrum contains anywhere between one and eight `quadrants'.

If for some reason you have to do this outside the das or aosc commands, use the

$\gt\!\gt$ set-quadrant-display

command. You will be asked to mask out (with a zero) each of the sections you are not using. Thus the DAS uses

$\gt\!\gt$s-q-d 1 1 1 1 1 1 1 1

and the AOSC requires

$\gt\!\gt$s-q-d 1 0 0 0 0 0 0 0

Now you are ready to start reading data. This setup will do to get you started at the JCMT. The first thing you will want to do is look at your first spectrum.