APEX: Important recent changes regarding Instrumentation and Facilities

This section describes important changes which took place during Periods 105 and 106, as well as changes expected to take place during Periods 107 and 108.


Proposal anonymisation:

Period 108 marks 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 108. 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 108.

Dates for ESO observing time:

The dates for the ESO observing time in Period 108 are foreseen to be from 15 August to 6 September, from 21 October to 2 November, and from 8 to 20 December 2021. Time critical observations should only be requested within these time slots. Users are encouraged to check the latest version of the schedule.

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:

Monitoring and Large programmes will be accepted for ARTEMIS, SEPIA,  and nFLASH.


  • 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.