Science Highlight




Cycle 8 Pre-Announcement

UPDATE: The 2020 Cycle 8 Call was suspended due to the COVID-19 pandemic. Please see the 2021 Cycle 8 Pre-announcement here.

The Joint ALMA Observatory (JAO) will start the next cycle of observations (Cycle 8) in October 2020. A Call for Proposals (CfP) with detailed information on Cycle 8 will be issued in March 2020 and the deadline for proposal submission will be in April 2020. This pre-announcement highlights aspects of the Cycle 8 CfP to assist with early planning.


General information


ALMA Cycle 8 will start in October 2020 and span 12 months. The JAO anticipates having 4300 hours for approved science observations on the 12-m Array and 3000 hours on the Atacama Compact Array (ACA), also known as the Morita Array.

The key dates (anticipated) for Cycle 8 are:

19 December 2019

Cycle 8 pre-announcement

17 March 2020

Release of the ALMA Cycle 8 Call for Proposals and Observing Tool, and opening of archive for proposal submission

15 April 2020

Proposal submission deadline

End of July 2020

Results of the proposal review sent to proposers

9 September 2020

Deadline for phase 2 submission by PIs or designees

15 September 2020

Release of ACA Supplemental Call for Proposals

30 September 2020

End of Cycle 7 observations

1 October 2020

Start of Cycle 8 observations

8 October 2020           

Supplemental Call deadline


Proposal types in Cycle 8 will include Regular, Very Long Baseline Interferometry (VLBI), Target of Opportunity, and Large Program. VLBI proposals work in concert with the Global mm-VLBI Array (GMVA) or the Event Horizon Telescope (EHT). GMVA programs must also submit a proposal to the GMVA by its 1 February 2020 deadline. Additional information about proposing with ALMA using the GMVA will be made available in the GMVA Call for Proposals in early January 2020.

Antenna configurations for the main 12-m array will use a new nomenclature in Cycle 8. Configurations will be called C-1, C-2, and so on up to C-10, with C-1 having similar characteristics to the C43-1 configuration of Cycle 7, and likewise for the others. Cycle 8 will not include the two longest baseline 12-m array configurations, C-9 and C-10. Maximum baselines in Cycle 8 will therefore be 8.5 km in configuration C-8. Configurations C-9 and C-10 with maximum baselines of 13.9 km and 16.2 km, respectively, will again be available in Cycle 9.

In addition to the main Cycle 8 CfP, the JAO will issue a Supplemental Call for proposals in Cycle 8 to use the ACA in stand-alone mode. More information on the Supplemental Call is given below.


New in Cycle 8


In Cycle 8, the following technical capabilities will be available for the first time:

  • Solar observations in Band 5
  • VLBI observations of faint science targets (correlated flux density <500 mJy within an unresolved core on ALMA baselines up to 1 km). These observations will be done in passive phasing mode, where it is recommended to have a bright calibrator within 5 deg of the science target.
  • High-frequency observations (Bands 9 and 10) with the stand-alone 7-m Array
  • Mosaicking of continuum linear polarization observations (Bands 3 to 7)
  • Spectral scans with the 7-m Array


Dual-Anonymous Proposal Review


Proposals in Cycle 8 will implement a dual-anonymous process for proposal reviews. While proposers will still enter their names and affiliations in the Observing Tool, their identities will be concealed from the reviewers. It will be the responsibility of the investigators to write their proposals such that anonymity is preserved. Guidelines on how to prepare such proposals will be presented in a forthcoming ALMA news item and, later, in the CfP.


Technical Capabilities


The anticipated Cycle 8 capabilities are:

Number of antennas

  • At least 43 antennas will be available from the 12-m Array
  • At least ten 7-m antennas (for short baselines) and three 12-m antennas (for single-dish maps) will be available in the ACA

Receiver bands

  • Receiver Bands 3, 4, 5, 6, 7, 8, 9 and 10 (wavelengths of about 3.1, 2.1, 1.6, 1.3, 0.87, 0.74, 0.44 and 0.35 mm, respectively)

12-m Array Configurations

  • Maximum baselines for the antenna configurations will vary from 0.16 km to 8.5 km. Configurations C-9 and C-10 will not be offered in Cycle 8.
  • Maximum baselines of 3.6 km for Bands 8, 9 and 10
  • Maximum baselines of 8.5 km for Bands 3 to 7

Spectral line, continuum, and mosaic observations

  • Spectral line and continuum observations with the 12-m Array and the 7-m Array in all bands
  • Single field interferometry (all bands) and mosaics (Bands 3 to 9) with the 12-m Array and the 7-m Array
  • Single dish spectral line observations in Bands 3 to 8


  • Single pointing, on-axis, full, linear and circular polarization for both continuum and full-spectral-resolution observations in Bands 3, 4, 5, 6, and 7 on the 12-m Array.
  • Linear polarization imaging of a compact source on-axis in both continuum and full spectral resolution modes is feasible at the level of 0.1% (3 sigma) fractional polarization for the very brightest calibrators, and 0.2% (3 sigma) level for a typical observation.
  • The minimum detectable degree of circular polarization is 1.8% of the peak flux for both continuum and full spectral resolution observations.
  • Mosaicking of continuum linear polarization observations (Bands 3 to 7).


Configuration schedule


The following table summarizes the anticipated configuration schedule for Cycle 8. The table includes the start date of the configuration, the longest baseline, and the LST range with the best atmospheric stability, which is approximately from 2 hours after sunset to 4 hours after sunrise. The configuration schedule may be modified based on the Cycle 8 proposal pressure.

Start date


Longest baseline

LST for best observing conditions

2020 October 1


8.5 km

~ 22—10 h

2020 October 20


3.6 km

~ 23—11 h

2020 November 10


2.5 km

~ 1—13 h

2020 December 1


1.4 km

~ 2—14 h

2020 December 20


0.78 km

~ 4—15 h

2021 January 10


0.50 km

~ 5—17 h

2021 February 1

No observations due to maintenance

2021 March 1


0.16 km

~ 8—21 h

2021 March 26


0.31 km

~ 9—23 h

2021 April 20


0.50 km

~ 11—0 h

2021 May 10


0.78 km

~ 12—2 h

2021 May 31


1.4 km

~ 13—4 h

2021 June 23


2.5 km

~15—6 h

2021 July 28


1.4 km

~17—7 h

2021 August 18


0.78 km

~19—8 h

2021 September 10


0.50 km

~20—9 h


Table 1: Cycle 8 configuration schedule


Large Programs


Up to 15% of the time in Cycle 8 may be allocated to Large Programs (645 hours for the 12-m Array and 450 hours for stand-alone ACA). The definition of Large Programs, evaluation criteria, and scheduling constraints will be the same as in Cycle 7 (see Cycle 7 Proposers Guide for more information). Proposers should consider the expected amount of time available versus LST per configuration (see Figure 1) together with the scheduling constraints to calculate the amount of time available for Large Programs at a given LST and configuration.




Figure 1: Effective observing time available per configuration for executing PI projects. For example, up to 36 hours are expected to be available in C-4 at LST 00 h for all observations and up to 18 h of those may be allocated to Large Programs. The total number of hours excludes time spent on observatory calibration, maintenance, reconfigurations, and other activities. The time available for Large Programs is shown in pink and time for high-frequency observations in green and dark blue. The configuration schedule and, consequently, the total number of hours available per configuration may change in response to proposal pressure. The data files containing these histograms are available here.


Stand-alone ACA Supplemental Call for Proposals


In Cycle 8, ALMA will offer a stand-alone ACA Supplemental Call for Proposals. The Supplemental Call will open on 15 September 2020 and the proposal deadline will be on 8 October 2020. Observations from the Supplemental Call will be scheduled from January 2021 to September 2021. The anticipated amount of time available will be announced in the Call. While stand-alone ACA proposals accepted from the Main Call may be assigned priority "A", "B", or "C", all accepted proposals from the Supplemental Call will be assigned priority "C". Proposals submitted to the Supplemental Call will be peer reviewed through a distributed system, in which the PI of each submitted proposal, or a designee from among the co-Is, will be responsible for reviewing ten other proposals submitted in the same call.