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DRIFT SCAN TABLE COMMANDS

The drift scan table allows the CCD chip to be tracked relative to the observed field and to be read out one column at at time as it is moved. The telescope must be autoguided for drift scan exposures. The increment by which the table is moved is equal to the pixel size of the chip being used (22 microns for the GEC chip and 30 microns for the RCA chip). These quantities cannot be changed by the user. The position of the drift scan table is known to about 1 micron (0.014 arc seconds at the JKT f/15 focus). The maximum allowed unvignetted scan length is 650 arc seconds.

• DRIFT - Carry out a drift scan run
• TABLE - Move the drift scan table to position n
• TABLE? - Drift scan table position status
• CENTRE - Return drift scan table to its centre position