Performing interactive analyses

Interactive measurement is performed in PHOTOM using a program which is also called PHOTOM¹. Alternatively, if it is available on your system, you can use the photometry toolbox which is part of the GAIA (SUN/214) display tool. In the following discussion it is assumed that you are using the PHOTOM program.

The first thing you need to do is display your image. Although PHOTOM can work using a display that does not have an overlay, it is best to have one. This is so that any line graphics which PHOTOM draws can be erased. Without this ability the display becomes quickly confused, particularly when setting the size and orientation of the aperture.

You can create a GWM X-windows display with an overlay using the command:

% xmake xwindows -overlay -ovcolour green

and can display an image in this window either using the KAPPA (SUN/95) DISPLAY program, or if this isn't available the PHOTGREY program.

You can now start up the main PHOTOM program by typing the command:

% photom

this could be from the C-shell or ICL.

The first response from this program is a request for the name of the image you have just displayed. This image remains open until you exit from PHOTOM. If you need to measure objects in another image then you should exit PHOTOM, display the new image and then restart PHOTOM.

The next request should be for a parameter ``COMMAND'' which indicates that you are now in the main command loop of PHOTOM. Your response to this prompt should be a single character. To see a menu of the possible commands return a `h' (or `H').

The first time one of the interactive graphical options: I - interactive shape (aperture photometry only); or M - interactive measurement is selected the name of the display device is requested. If you are using an image display with overlay capabilities then remember that the overlay device is not the same as the device you displayed your image in, e.g. if you displayed on an X-windows device `xw', then the overlay device is called `xov'.

Typically the cursor position is controlled by the mouse and the mouse button meanings are indicated by three menu boxes drawn on the screen. If you use an unusual display device without a mouse then the graphics are controlled by the keyboard. A message from PHOTOM shows which of these options applies to you.