CAOBS

CAOBS is the interface between the observer and the telescope. It coordinates the functions of the antennas and the correlator. It runs on XBONES and is normally displayed on a PERICLES terminal in the Control Room. The usual appearance of this display is shown in the figure below

Figure 8.3: A typical CAOBS display.

To display this CAOBS status page at any time use:

CAOBS> show status

shows the CAOBS status page

Spend a minute to look at all the fields on this screen as it displays information that you might consider important, such as the coordinates and frequency you happen to be using. The topmost section displays the source name and the coordinates and epoch specified by your schedule file. The observing frequency and bandwidth appear underneath the coordinates. Ignore the V(LSR) field. The next line lists the number of the current scan, and presents the times at which this scan begins and ends. The Tsys field should usually read ON. (It is turned off in some 3mm observations, and for some maintenance modes) To turn the $Tsys$ calculation back on, enter the command:

CAOBS> enable tsys

enables $Tsys$ calculation

Below the scan times are six fields that display the status of each antenna. The antennas are labelled ``CA0n'', where ``CA'' stands for Compact Array and ``0n'' is the antenna number. If you need to find an antenna, note that they are numbered from one to six, going east to west. The field called cycle indicates how many integrations have occurred during the current scan.

The second screen element of the CAOBS display is the scan cycle display. This display keeps you informed about what CAOBS is doing. For example, messages appear here to reassure you that scans have started. Note that the Universal and Sidereal time are displayed under this display. The third part of the CAOBS screen displays messages on a per antenna basis. Observe that the Universal time of message display appears on the left.

To enter a CAOBS command, type slowly and note that what you type appears in the data entry region at the bottom of the screen. You can use the delete key (left of the Back Space key) to edit commands before you press the Return key. CAOBS commands (like all other AT online commands) are not case sensitive.

CAOBS is vital to ATCA observations. You should look at the CAOBS screen often during observations to ensure that scans occur as expected.

Note that the online computers participate in numerous dialogues with each other and system hardware. Response times can sometimes be slow and restarting major programs takes a few minutes.

Supplementary information about CAOBS can be found on the ATNF CAOBS page.