Science Highlight




ALMA Cycle 3 Pre-announcement

The Joint ALMA Observatory (JAO) will start the next cycle of observing (Cycle 3) in October 2015. A Call for Proposals will be issued on March 24, 2015, with an anticipated deadline for proposal submission on April 23, 2015. Cycle 3 operations will include standard and nonstandard modes (see below), with only non-standard mode observations being conducted on a best-effort basis, similar to projects in previous Cycles.  ALMA has entered into a phase where PI-science observations dominate activities while continued improvements and developments are also explored.

Detailed information on Cycle 3 will be published in the Call for Proposals.

General information

ALMA Early Science Cycle 3 will start in October 2015 and span 12 months. During this period a fraction of time will be reserved for engineering and commissioning work to realize the full suite of ALMA capabilities. It is anticipated that 2100 hours of both 12-m Array and ACA (Atacama Compact Array) time will be available for Cycle 3 proposals that are assigned highest priority based on their scientific ranking by the ALMA Proposal Review Committee. Only uncompleted Cycle 2 “A” graded proposals will transfer into Cycle 3, regardless of the overall completion percentage. This means that PIs with "Cycle 1 Transfer" or Cycle 2 “B” graded proposals that remain uncompleted by the Cycle 3 proposal deadline (April 2015) should consider resubmitting these proposals.

Any registered user may submit a proposal in response to the ALMA Cycle 3 Call for Proposals. Successful proposers for nonstandard mode projects will share risk with ALMA: while Observatory staff will conduct quality assurance on the data, and will provide reduced data products through the respective ALMA Regional Centers (ARCs), it cannot be guaranteed that the characterization and quality of the data and data products will meet the standard expected for ALMA in full scientific operations. Calibration performance will be consistent with the specifications given in the Cycle 3 Proposers Guide published at the call for proposals.

Proposers may check the observational status of their Cycle 1 and 2 projects using the Project Tracker, available at the Science Portal.

Anticipated Capabilities

Detailed information on Cycle 3 capabilities will be published in the Call for Proposals. As of the date of this pre-announcement, the ALMA Cycle 3 anticipated capabilities comprise:

  • At least thirty-six 12-m antennas in the main array, and ten 7-m antennas (for short baselines) and two 12-m antennas (for making single-dish maps) in the Atacama Compact Array (ACA)
  • Receiver bands 3, 4, 6, 7, 8, 9, & 10 (wavelengths of about 3.1, 2.1, 1.3, 0.87, 0.74, 0.44, and 0.35 mm)
  • Baselines up to 2 km for Bands 8, 9 and 10
  • Baselines up to 5 km for Band 7
  • Baselines up to 10 km for Bands 3, 4, & 6
  • Both single field interferometry and mosaics
  • Spectral-line observations with all Arrays and continuum observations with the 12-m Array and the 7-m Array.
  • Polarization (on-axis, continuum in Band 3, 6 and 7, no ACA, no mosaics, no spectral line, no circular polarization)
  • Mixed correlator modes (both high and low frequency resolution in the same observation)


Use of the ACA for short baseline interferometry and single-dish observations will only be offered to complement observations with the 12-m Array, and not as a stand-alone capability. Single dish use will be limited to spectral line observations in Bands 3 to 8.

The number of array elements available for science observing is less than the number available overall. This is due to, among other things, maintenance activity, especially during daytime observing.  It is expected that the number of array elements available for use will grow over the course of the cycle.

Standard observing modes are those that have been used in previous Cycles and for which the data can be reduced by the pipeline. Non-standard modes are observing modes for which the data need to be processed by ALMA staff. Up to 25% of the total observing time will be assigned to such projects. Non-standard modes include:

  • Bands 8, 9 & 10 observations
  • Long baselines (> 2km)
  • Polarization
  • Spectral Scans
  • All ephemeris observations
  • Bands ≥ 7 with all narrow band spectral windows
  • Non-standard calibrations


Key dates

The key dates for Cycle 3 are given below.

  • 24 March 2015: Call for Proposals for ALMA Early Science Cycle 3, release of Observing Tool, and opening of the Archive for proposal submission.
  • 23 April 2015: Proposal Deadline.
  • August 2015: Result of the proposal review process sent to PIs.
  • October 2015: Start of ALMA Cycle 3 observations.
  • September 2016: End of ALMA Cycle 3 observations.