Almost always, this is due to a "feature" of the image display software: it will not always display images automatically if the product of itime x coadds is less than 1 second. For example, an image of 1 coadd with 0.25 sec itime will not automatically be displayed. The image has been recorded normally in /tmp if it is a test or in your data directory if it is a go, and it can be opened by hand with the FILE - Open menu option.

The root cause is that the automatic display does not work by listening for "image taken" signals from the server, but instead by polling the output directories once per second and checking the update times on the files. Images of less than 1 second duration look too "old" to the polling logic and are never picked up.

If you want the image to display automatically every time, choose coadds such that the product of itime x coadds is always at least 1 second.

In rare cases, this could be a symptom of a complete lockup. If an image with the product of itime x coadds > 1 sec does not display, then try a benign menu entry like FILE - "Open" to see if the display window is still alive. If not proceed to the instructions below.

Sometimes either the SCAM or SPEC QuickLook window will disappear or will lock up and not respond to further mouse clicks. If this happens, try to find out and record what the user was doing at the time, as a lockup is sometimes a symptom of a bug. One known problem, not likely to be fixed or even fixable, is that having more than one or two of the popup feature panels open at a time can cause a lockup. For example, if the users have the vertical plot, statistics, Gaussian fit, and surface plot popups all open at once, they're asking for trouble. QuickLook crashes can also happen for no good reason at all, however, so don't go nuts trying to figure it out.

If it happens, first see if you can exit the offending window normally, by going into the FILE menu and selecting the "Quit All" option. If this doesn't work (and it usually won't, but it can't hurt to try), look on the same monitor for a cmdtool or xterm icon with the same name ("SCAM" or "SPEC") as the broken display. Open that terminal window, and examine whatever IDL error messages are present. If you can understand the errors, make a note of them to help diagnose what caused the crash. Hit "enter" a couple of times to get an IDL prompt back, then enter the IDL command "exit". If you can't get a prompt back, quit the terminal window from the window manager by putting the mouse on the window's title bar, holding down the right mouse button and letting up on "Quit". Either way, both the terminal window and the display window should disappear.

Now, kill the other QuickLook display window using the FILE menu's "Quit All" option. This one must be killed because the restart starts fresh copies of both displays, and we don't want extra copies of the survivor choking things up. Now you can restart the QuickLook displays by going to the blue background on the middle monitor (QuickLook is NOT recommended on the 8-bit color right monitors), holding down the right mouse button, going into "NIRSPEC Control Menu" and letting up on "Restart Quick Look" option.

It is a known problem with the QuickLook displays that only one plot popup can be functional at a time. If the user has selected and used "Vertical Plot" from the PLOT menu, and then selects "Horizontal Plot" without first dismissing (using the "Done" or "Cancel" buttons) the "Vertical Plot", then the "Vertical Plot" will stop working. Even if the second plot popup is dismissed, the first one will not resume functioning. In this example, to use "Vertical Plot" again, the user would have to dismiss both popups, then reselect "Vertical Plot" from the menu.

As a rule, it is a Very Good Idea to have only one popup open at a time. It is also a Very Good Idea to dismiss each popup immediately as soon as you're done with it. Not only does this avoid confusion about which one is "alive" but it also may reduce the chances of a crash.

There is a known problem with the "Diagonal Cut" plot function conflicting with "Move Telescope." If the user starts "Diagonal Cut" and then fails to dismiss the popup before the next use of "Move Telescope," then "Move Telescope" will not work. The usual symptoms are that "Move Telescope" gives the first prompt ("Click Mouse on Start Point") as usual, but never returns with the second prompt ("Click Mouse on End Point").

The solution is simple: dismiss the "Diagonal Cut" popup by clicking the "Done" button. The "Move Telescope" function should then work again.

On rare occasions, there may be something more serious wrong. If just dismissing the "Diagonal Cut" popup does not fix it, then try stopping and restarting both QuickLook displays as described in the section above (second paragraph).

As a rule, it is a Very Good Idea to have only one popup open at a time. It is also a Very Good Idea to dismiss each popup immediately as soon as you're done with it. Not only does this avoid confusion about which one is "alive" but it also may reduce the chances of a crash.