Using CAOBS

As described earlier, CAOBS is the main interface with the observer. You use CAOBS to control the array: to initiate observations, track sky positions and stow the antennas. You also use CAOBS to stop a scan and close data files. You should close your data files about once every three hours as a precautionary measure, or if the files size exceeds 125 Mbytes. In a simple observation, the following commands may well be the only ones you use:

Load your schedule files	CAOBS$>$ set file filename
Track your first calibrator (normally 1934-638)	CAOBS$>$ track 1
Stop scans	CAOBS$>$ stop
Close data files	CAOBS$>$ corr closefile
Start long observations. Data files are opened automatically every time you use the start command if a file is not already open.	CAOBS$>$ start 1/100 (to start the scan at the first object in the schedule file and repeat the entire schedule file 100 times).
Stow the array	CAOBS$>$ stow

A common observing problem which requires action in CAOBS is an ACC crash. ASSISTANCE will inform you that ``The ACC in antenna n appears to have died". To fix reset the ACC in question by:

CAOBS$>$ reset ca0n

Where n is the number of the antenna.

Sometimes an ACC crash causes CAOBS to hang: In this case you need crash out of CAOBS and restart the ACC from the XBONES command line i.e.

	CAOBS$>$ Press +		To escape from the hung CAOBS
	XBONES$ accreset		to actually reset

When an ACC is `dead', the antenna image in the ATDRIVEMON display is distorted. (See 7.1 on  for an example.) When this image has returned to `normal' you can restart your observations. For more information on this fault see acc_comms_errors