ALMA Early Science Cycle 0 status report

ALMA started scientific operations on 30 September 2011. While the quality of the data being collected is excellent, the completion rate of projects is lower than planned. To increase the likelihood that most PIs of the highest priority Cycle 0 projects will receive scientifically valuable data sets, the Cycle 0 observing period will be extended until the end of 2012. This extension will not delay completion of the array.

The observatory plans to release information regarding the capabilities and timeline for ALMA Early Science Cycle 1 in April 2012. The proposal deadline is expected to be in July 2012 with the start of Cycle 1 observations at the beginning of 2013.

Background

Early Science Cycle 0 observations have been conducted in blocks of 4-5 days every two weeks. By the end of January 2012 approximately 50% of the anticipated observing time for Cycle 0 has been used and we estimate that roughly 25% of the highest priority observations have been completed. While consistent with the “best efforts” basis of ALMA Early Science this is lower than we’d hoped. Sixteen calibrated, quality assured datasets have been delivered to PIs (by the end of January 2012). The data clearly demonstrate the scientific potential of ALMA, and feedback from the PIs has been positive.

Measures are being implemented to increase the observing efficiency, and during the additional period of Cycle 0 observing the fraction of ALMA time used for scientific operations will increase from the current fraction of 33% to around 50%. This corresponds to the intended fraction of time planned for science operations if Cycle 1 had begun as planned. With the increasing number of antennas it will be possible to schedule observations using the extended or compact configuration during the latter part of Cycle 0. There is also an increased likelihood that “filler projects”, particularly in band 3, will be observed.

Commissioning and science verification activities are being conducted in parallel with Cycle 0 observations. More ALMA “Science Verification” data has recently been posted to the Science Portal, and some has already started appearing on the astronomy abstract servers.

The highest priority of the ALMA project continues to be the completion of the full array, expected in the second half of 2013.