This section describes relevant changes for observations to take place during Period 101.

General

• In order to prepare APEX for continued operation till the end of 2022, the telescope will undergo major maintenance activities from September 2017 till January 2018. The telescope is expected to resume science operations in April or May 2018, after the completion of the re-commissioning activities. At the time of issuing this call, the ESO time slots have not been defined yet. Users should be aware of disruptions in the start of the Period 101 observations.
  
• Time critical observations in May-July 2018 will only be executed on a best effort basis.
• The ESO share in the APEX collaboration has increased from 27% to 32%. The exact distribution of the observing time between the APEX partners can be found on the APEX web pages.
  
• Large and Monitoring programmes will only be accepted for ARTEMIS and SEPIA.
  

Instruments

• ARTEMIS has been offered since Period 99. In Period 101, both the 350 and 450 μm channels are offered for simultaneous observations. This instrument is optimized for wide-field mapping of areas of at least 4'x2', and achieves similar mapping speeds at both wavelengths. An observing time calculator is available.
  
• SEPIA can house up 3 ALMA-type receiver cartridges.
  
  • Since Period 101, three receivers are available:
    
    • a band 5 receiver, covering 159 to 211 GHz with dual polarization, sideband-separating mixers (2SB),
      
    • a new band 7 receiver (272 to 376 GHz) with dual polarization, sideband-separating (2SB) mixers,
    • a band 9 receiver, covering 600 to 722 GHz with dual polarization, double-sideband mixers.
      
  • Only the band 5  receiver is available for Monitoring and Large Programmes.
  • The band 7 receiver is offered conditional to a successful commissioning in March 2018, and replaces the SHFI/APEX-2 receiver.
    
  • The band 9 receiver will be upgraded with 2SB mixers over the course of 2018.
  • All receivers use the XFFTS backends, covering 4 GHz IF bandwidth. In the 2SB receiver of band 5 and 7, both bands are recorded, while in the DSB receiver of band 9, only one band is recorded. In both cases, there is a gap of 8 GHz between the image and signal bands.
    
  • An observing time calculator for all bands is available.
• PI230: This new 230 GHz receiver covering 200 to 270 GHz is offered as a replacement of the SHFI/APEX-1 receiver. It is a dual polarization, sideband-separating (2SB) receiver with an IF coverage of 8 GHz per sideband. There is a gap of 8 GHz between both sidebands. The backends are 4th generation Fourier Transform Spectrometers (FFTS4G) with 2x4 GHz bandwidth. A more detailed description is available in the presentation "A-MKID, PI-230, LAsMA - new MPIfR receivers for APEX". An observing time calculator for both bands is available.
  
• SHFI has been decommissioned in September 2017. The APEX-1 receiver has been replaced by the PI230 instrument, and the APEX-2 receiver by the band 7 receiver of SEPIA.
  
• FLASH This MPIfR PI instrument is no longer offered, as during the 2nd half of 2018, it will be replaced by a new instrument SLASH which will contain a band 6 (200 to 270 GHz) and band 8 (385 to 500 GHz) receiver.
• CHAMP+: This MPIfR PI instrument is not offered in Period 101 because of ongoing re-commissioning activities.