Issue affecting some proposals requiring ACA observations

An issue has been discovered in the Cycle 10 ALMA Observing Tool (OT) that affects the estimated Atacama Compact Array (ACA) integration times for some 4x4-bit ACA observations (7-m and TP). The issue occurs when the Bandwidth used for Sensitivity in the "Control and Performance" section is set to anything other than RepWindowEffectiveChannelWidth or FinestEffectiveChannelWidth. This is a result of an error in the implementation of the 4x4-bit spectral mode for improved sensitivity (that is offered in Cycle 10 on the 12-m Array only), which causes the integration times for 4x4-bit ACA observations calculated by the OT to be erroneously too short unless the above bandwidth for sensitivity options are selected. We have fixed this problem and a patched version of the Cycle 10 OT is now available on the Science Portal. All PIs of projects that include ACA observations should download the updated OT version and submit or resubmit their proposals using this version. The correct version can be identified by checking for the words “Patch 1” in the title bar at the top of the OT window.

We regret any inconvenience or impact experienced by our ALMA users due to this issue. If you have any questions, or have comments or concerns, please contact your local ALMA Regional Centre via the ALMA Helpdesk at https://help.almascience.org/.