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ALMA Cycle 7 Pre-Announcement

Dec 19, 2018

The Joint ALMA Observatory (JAO) will start the next cycle of observations (Cycle 7) in October 2019. A Call for Proposals (CfP) with detailed information on Cycle 7 will be issued in March 2019, with a deadline for proposal submission in April 2019. This pre-announcement highlights aspects of the Cycle 7 proposal Call that are needed to plan proposals.

 

General information

 

ALMA Cycle 7 will start in early October 2019 and span 12 months. It is anticipated that 4300 hours of 12-m Array time will be available for successful observations of approved projects, and 3000 hours will be available on the Atacama Compact Array (ACA), also known as the Morita Array.

The key dates for Cycle 7 are given below.

19 December 2018

Cycle 7 pre-announcement

19 March 2019 (15:00 UT)

Release of the ALMA Cycle 7 Call for Proposals and Observing Tool, and opening of archive for proposal submission

17 April 2019 (15:00 UT)

Proposal submission deadline

End of July 2019

Result of the proposal review sent to proposers

5 September 2019

Deadline for phase 2 submission by proposers

October 2019

Start of Cycle 7 observations

September 2020           

End of Cycle 7 observations

 

The same proposal types as in the previous cycle will be accepted. Principal Investigators submitting a proposal to ALMA for Very Long Baseline Interferometry (VLBI) observations in ALMA Band 3 made in concert with the Global mm-VLBI Array (GMVA) at 3 mm must also submit a proposal to the GMVA by its 1 February 2019 deadline. Additional information about proposing with ALMA using the GMVA will be made available in the GMVA Call for Proposals in early January 2019. 

In addition, in Cycle 7 JAO will issue a Supplemental Call for stand-alone ACA observations to be scheduled from January 2020 to September 2020 making use of the same technical capabilities as those of the Main Call. The Supplemental Call will have some differences compared to the Main Call including the scheduling priority of the observations and the proposal review process (see below for more information). 

 

New in Cycle 7

 

In Cycle 7, the following technical capabilities will be available for the first time:

-       Observations in Band 7 in configurations C43-9 and C43-10.

-       Solar observations in Band 7 in configurations C43-1 and C43-2.

-       Solar observations in one additional configuration (C43-4) in Band 3.

-       Improved sensitivity limit for full spectral resolution linear polarization observations (see below). 

In addition, spectral scans will become a standard mode. Observations in Band 7 at baselines longer than 5 km will become a standard mode as long as there is expected to be a suitable phase calibrator within 5 degrees of the science target (see below).

Finally, the data rate limitation from previous cycles will be significantly relaxed so that PIs will be able, for example, to set up high spectral resolution windows in long baseline configurations that were previously hampered due to high data rates.

 

Technical Capabilities

 

The anticipated Cycle 7 capabilities are:

Number of antennas

    • At least forty-three (43) antennas in the 12-m Array
    • At least ten (10) 7-m antennas (for short baselines) and three (3) 12-m antennas (for making single-dish maps) 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 16.2 km
    • Maximum baselines of 3.6 km for Bands 8, 9 and 10
    • Maximum baselines of 16.2 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

Polarization

    • Single pointing, on axis, full, linear and circular polarization for both continuum and full-spectral-resolution observations in Band 3, 4, 5, 6, and 7 on the 12-m Array. The field of view of linear and circular polarization observations is limited to the inner one-third and one-tenth of the primary beam, respectively. 
    • 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.

As in previous cycles, Cycle 7 observing modes will be classified as standard or non-standard. Standard modes have been well characterized and the observations are calibrated and imaged with the ALMA data reduction pipeline. Non-standard modes are not as well characterized and may require manual calibration and imaging by ALMA staff. Up to 20% of the observing time in Cycle 7 will be allocated to proposals requesting any of the non-standard modes listed below:

    • Band 7 observations with baselines longer than 5 km if the phase calibrator is expected to be further than 5 degrees from the science target (the Observing Tool used for proposal submission will assess the availability of suitable phase calibrators and will issue a warning in such a case)
    • Band 9 and 10 observations
    • All polarization observations
    • Bandwidth switching projects (less than 0.9375 GHz aggregate bandwidths over all spectral windows)
    • Solar observations
    • VLBI observations
    • User-specified calibrations
    • Astrometry

 

Configuration schedule

 

The representative antenna configurations in Cycle 7 are the same as in Cycle 6. The corresponding files needed for CASA simulations are available on the Science Portal

Table 1 summarizes the anticipated configuration schedule for Cycle 7. 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 7 proposal pressure. 

Start date

Configuration

Longest baseline

LST for best observing conditions

2019 October 1

C43-4

0.78 km

~ 22—10 h

2019 October 20

C43-3

0.50 km

~ 23—11 h

2019 November 10

C43-2

0.31 km

~ 1—13 h

2019 November 30

C43-1

0.16 km

~ 2—14 h

2019 December 20

C43-2

0.31 km

~ 4—15 h

2020 January 10

C43-3

0.50 km

~ 5—17 h

2020 February 1

No observations due to maintenance

2020 March 1

C43-4

0.78 km

~ 8—21 h

2020 March 20

C43-5

1.4 km

~ 9—23 h

2020 April 20

C43-6

2.5 km

~ 11—1 h

2020 May 20

C43-7

3.6 km

~ 13—3 h

2020 June 20

C43-8

8.5 km

~ 15—5 h

2020 July 11

C43-9

13.9 km

~16—6 h

2020 July 30

C43-10

16.2 km

~17—7 h

2020 August 20

C43-9

13.9 km

~19—8 h

2020 September 10

C43-8

8.5 km

~20—9 h

 

Table 1: Cycle 7 configuration schedule

 

Planning Large Programmes

 

Up to 15% of the time in Cycle 7 may be allocated to Large Programmes; i.e., 645 hours for the 12-m Array and 450 hours for stand-alone ACA. The definition of Large Programmes, evaluation criteria and scheduling constraints will be the same as in Cycle 6 (see Cycle 6 Proposers Guide for detailed 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 Programmes at a given LST and configuration.

 

Cycle 7 Pressure 

 

Figure 1: Effective observing time available per configuration for executing PI projects. As an example, up to 30 hours are expected to be available in C43-2 at LST=10 h for all observations and up to 15 h may be allocated to Large Programmes. The total number of hours excludes time spent on observatory calibration, maintenance, reconfigurations, and other activities. The fraction of that time available for Large Programmes (pink) and high frequency observations (green and dark blue) is also indicated. The configuration schedule and, consequently, the total number of hours available per configuration may change as a result of proposal pressure. The data files containing these histograms are available here.

 

Stand-alone ACA Supplemental Call for Proposals

 

In Cycle 7, ALMA will offer a stand-alone ACA Supplemental Call for Proposals. It is anticipated that the Supplemental Call will be issued on 3 September 2019 with a proposal deadline on 1 October 2019. The Supplemental Call will maximize the scientific output of the ACA by allowing more timely science to be proposed since the Supplemental Call will follow the Main Call by five months. A minimum of 750 h of observing time on the ACA will be allocated through the Supplemental Call for observations between January 2020 and September 2020. 

Proposals may be submitted that use the 7-m Array only or the 7-m Array plus the Total Power array and with the same technical capabilities offered for the ACA in the Main Call. However, only regular proposals without time constraints will be allowed. As in the Main Call, stand-alone ACA observations are available for standard modes only. There will be no LST restriction on proposals at the time of submission. 

The prioritization of ACA observations in Cycle 7 will be as follows: proposals which require ACA time (in combination with the 12-m Array or stand-alone ACA observations only) will only be eligible for "A" or "B" priority in the Main Call; in the Supplemental Call, stand-alone ACA proposals accepted to the scheduling queue will be all given 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 designated reviewer selected from among the co-Is of the proposal, will be responsible for reviewing ten proposals submitted in the same call. The Science Portal includes a more detailed description of the Supplemental Call and the distributed peer review process, including answers to frequently asked questions, and up-to-date information about the implementation of the process in the Cycle 7 Supplemental Call.