Tracking Error Alarms

The Tracking Error Alarms dialog is launched by clicking the Alarms button on the Guide Tab. It allows you to define both the conditions that warrant a tracking alarm and the actions that MaxIm DL is to take when they occur. It is also used to acknowledge (reset) an alarm condition.

The two check boxes in the Trigger Alarm section define the conditions under which an alarm is issued. The first, If error exceeds, specifies a limit on the guide errors (X Err and Y Err as reported on the Guide Tab), together with the number of consecutive cycles (autoguider images) that the error must be out of limits before the alarm is triggered. The second, If guide star not detected, specifies that an alarm is raised if the guide star is lost or fades below the level at which MaxIm DL recognizes it, again for a certain number of consecutive cycles. You can select either, both, or neither type of alarm.

The Alarm Actions specify how MaxIm DL signals the occurrence of an alarm condition. First, the Tracking Error Alarms window is always displayed, regardless of which other actions are selected. In addition, if Flash this dialog box is checked, the caption bar will be flashed in Windows' traditional way of drawing attention. If Audible alarm is enabled, the WAV file named in the associated edit box is played. (Click the browse button to its right to call up a standard file dialog box for navigating to and picking the sound file.) If Repeat is checked, the sound will loop continuously until the alarm is acknowledged, otherwise it will play only once.  Execute script can be used for more elaborate alarm actions through the agency of a Windows Script Host script which you supply and whose actions you define. You specify this script with the file selector dialog activated through the browse button on this line.

What can a script do? It might, for example, capture a new full-frame autoguider exposure and examine it for potential guide stars, or simply abort any main camera exposure or sequence in progress. If the system is running unattended, it might be appropriate to send an email message reporting the problem. (Refer to the description of Scripting to learn about the capabilities MaxIm DL extends to scripts and the kinds of things that are possible.) An alarm script is executed by the command shell-based script host cscript.exe. If you do not want the command window to pop up in front of MaxIm DL, you can specify that it should run Minimized; the script window will still appear on the Windows Task bar and can be restored as long as it is still active.

When a tracking alarm occurs, the Acknowledge button is enabled. Clicking this button stops the window flashing and silences WAV file playback, but does not affect any script that may be executing. Note that MaxIm DL checks for tracking alarm conditions only after the previous alarm has been acknowledged.

Click Close to close the Tracking Error Alarms window. This also acknowledges any active alarm.