APEX: Important recent changes regarding Instrumentation and Facilities

This section describes important changes which took place during Period 108, as well as changes expected to take place during Periods 109 and 110.


Distributed Peer Review:

Starting from Period 110, ESO is introducing Distributed Peer Review (DPR) for approximately half of the submitted proposals. In this paradigm, first introduced by Merrifield & Saari (2009), all PIs of proposals qualifying for DPR accept to review a number of proposals (N) submitted by their peers during the same cycle. Correspondingly, they accept that their proposals are reviewed by N peers who submitted proposals in the same cycle. More details and background information on DPR at ESO can be found in Patat et al. (2019), and users should familiarise themselves with the DPR rules and guidelines.
In Period 110, N = 10, and the criteria describing the proposals which qualify for DPR are as follows:

  1. All proposals requesting a total time (including overheads) less than 16 hours are assigned to DPR. This time threshold is set to have an approximate 50/50 distribution between DPR and panels, and it is based on the time request statistics compiled in recent cycles.
  2. Exceptions to this general rule are proposals including at least one ToO run, and DDT proposals.
  3. All other proposals submitted during a regular cycle will be reviewed in the classical way by the OPC and the panels.

In Period 110, the review channel (DPR vs. panels) is assigned at the time of proposal submission, based on the above rules. The PI (or delegated PI; dPI) is informed about the assigned review process and prompted to formally accept the conditions at the time of submission. At this stage the PI/dPI can delegate the reviewer’s role to one of the co-Is listed in the proposal. The delegation can also occur when the list of co-Is is specified.

By submitting a proposal qualifying for DPR, the PI/dPI commits to follow the DPR rules (see DPR rules and guidelines).

New scientific keywords:

Starting in Period 110, a new set of scientific keywords replaces the OPC categories. While preparing their proposals in p1, users must select at least two keywords, and at most five keywords (ten keywords for Large Programmes), except that proposals for Calibration Programmes do not require any keywords. The keywords must be selected in decreasing order of relevance (i.e., the first selected keyword is the most relevant).

Proposal anonymisation:

Period 108 marked the full deployment of the Dual-Anonymous Peer Review (DAPR) for proposals submitted to this Call. Applicants must formulate the scientific rationales of their proposals following the anonymisation rules and examples described in this link, which also gives a detailed description of the DAPR paradigm. While Period 106 was used as a dry run, both to make the community aware of the upcoming implementation of DAPR and to test its practical, procedural and policy aspects, from Period 108 proposal anonymisation is mandatory. Failure to abide by the DAPR rules may be penalised.

The fields Background and Expertise and Data Product Delivery Plan (in the case of Large Programmes) are the only fields of the proposal in which information on the proposing team can be disclosed. These fields will not be included in the material distributed to the referees during the proposal review phase and will only be accessible to them after the ranking phase is completed.

Large Programs:

Large Programmes, those that require 100 hours or more, are accepted for Period 110. Large Programmes can only be submitted in even Periods, i.e., Periods with the proposal submission deadline in March/April. A number of instrument restrictions for Large or Monitoring Programs apply. We refer the reader to Sect. 4.4 in the Call for Proposals Period 110.

Dates for ESO observing time:

In Period 110, the ESO time slots are currently planned for 19–31 August, 12 October to 4 November and 3–14 December. Users are encouraged to check the latest version of the schedule. Time critical observations can only be executed during ESO time lots.

Length of normal programmes:

In order to solicit longer normal programmes for observations that do not require the best weather conditions, the maximum length of normal programmes on nFLASH-230 has been raised to 199 hours that require PWV > 2mm. For any other instrument, the limit remains 99 hours. Any nFLASH-230 programmes requiring 200 hours or more should be requested as Large Programmes.

Monitoring and Large programmes:

Only Large programmes (no Monitoring programmes) can be accepted for ARTEMIS, SEPIA, CONCERTO, LASMA, and nFLASH. In addition, APEX observations can only be carried out in the ESO time slots. Therefore, LPs for APEX can only include runs for Period 110.


  • ARTEMIS: In Period 108, both the 350 μm and 450 μm channels are offered for simultaneous observations. This instrument is optimised for wide-field mapping of areas of at least 40 × 20, and achieves similar mapping speeds at both wavelengths. An observing time calculator is available.
  • nFLASH: This facility instrument contains two receivers: nFLASH-230, covering from 200 to 270 GHz, and nFLASH-460, covering from 385 to 500 GHz. Both are dual polarization 2SB receivers, and can be used simultaneously or independently in Period 108. The nFLASH- 230 receiver has an IF bandwidth coverage of 8 GHz with a gap of 8 GHz between the two sidebands; the nFLASH-460 receiver has a IF bandwidth coverage of 4 GHz per sideband. The backends are digital 4th generation Fourier Transform Spectrometers (dFFTS4G) with 24 GHz bandwidth. An observing time calculator is available.
  • SEPIA: This instrument houses three ALMA-type 2SB dual polarization receiver cartridges:
    • SEPIA-180 (ALMA Band 5) covering from 159 to 211 GHz;
    • SEPIA-345 (ALMA band 7) covering from 272 to 376 GHz;
    • SEPIA-660 (ALMA band 9) covering from 578 to 738 GHz (note the extended frequency coverage with respect to ALMA band 9).
    • All receivers are available for Monitoring and Large programmes.
    • All receivers use the dFFTS4G backends, covering the 4 GHz (for SEPIA-180) or 8 GHz IF bandwidth with a gap of 8 GHz between the image and signal bands.
    • An observing time calculator for all bands is available.
  • CONCERTO: This PI instrument covers a circular field of view of 20 arcminutes, with a spectral resolution with a spectral resolution that can be chosen from R~1 (dual-band photometer) to R= 300". The frequency ranges are 130 to 270 GHz in the low frequency array and 195 to 310 GHz in the high frequency array, which are obtained simultaneously. For more details, see https://www.apex-telescope.org/ns/concerto/. Prospective users should contact the instrument PI Guilaine Lagache (guilaine.lagache [at] lam.fr) at least 2 weeks before the proposal deadline, and should include at least one member from the CONCERTO instrument team as coI on the proposal. An observing time calculator script is available from https://mission.lam.fr/concerto/pages/instrument.html.
  • LASMA: This PI instrument has 7 pixels with an RF range from 268 to 375 GHz in two sideband-separating bands covering 4 to 8 GHz IF. LASMA is offered to the ESO community on a collaborative and best effort basis with MPIfR. Users who would like to use LASMA must contact the instrument PI, Dr Friedrich Wyrowski (wyrowski [at] mpifr-bonn.mpg.de) at least two weeks prior to submitting their proposal. Members of the PI team should be included as CoIs on the proposal.