In its early cycles, it was only possible to obtain time on the ACA as part of observations conducted on the 12-m Array i.e. the shorter baselines of the ACA were required to image the largest angular scales in the source. However, this restriction was dropped in Cycle 4 and since then it has been possible to request time for the ACA only. This is referred to as the Stand-alone ACA (SACA) and allows a user to request time on the 7-m Array, together with the TP Array if required. It is not possible to request only the TP Array in the OT.
Most observing modes available on the 12-m Array time can also be requested with the SACA. There are though some exceptions, including observations requiring narrow (937.5 MHz) bandwidths.