APEX proposals

Call for proposals

Proposals are invited for observations with APEX in the period 10–27 August 2017.

Deadline: Friday 5 May 2017 (23:59:59 UTC)

 

APEX, the Atacama Pathfinder EXperiment, is a 12 m diameter submillimetre telescope at 5100 m altitude on Llano Chajnantor in Chile. The telescope is operated by Onsala Space Observatory, Max-Planck-Institut für Radioastronomie (MPIfR), and European Southern Observatory (ESO).

The available facility receivers are the Swedish Heterodyne Facility Instrument (SHeFI) covering a wide frequency range (currently 211-500 GHz) and the 870 μm LABOCA bolometer array.

The partner PI instrument ArTeMiS, a 350 and 450 μm bolometer array, can be requested for use on Swedish time under the same conditions as facility instruments. Other APEX partner instruments, including FLASH+, can also proposed for use during Swedish time but use of the instrument must be discussed with the instrument PI before the submisison of the proposal (see below).

SEPIA (Swedish ESO PI receiver for Apex) currently houses two heterodyne receivers: one for ALMA Band 5 (159–211 GHz, including the 183 GHz water line) and one for ALMA Band 9 (600–722 GHz). Proposals for observations with the SEPIA instrument must have a PI or co-I with a Swedish affiliation.

 

On this page you will find information about:
  • Observing period and operations
  • Telescope
  • Receivers
  • Proposals for Large Programmes
  • Proposal preparation and submission
  • Further information and useful links

Observing period and operations:

This Call for proposals is for Swedish time on APEX in the period 10–27 August 2017 (see the APEX Science schedule). The telescope will be closed down from October 2017 to the end of March 2018 for upgrades.

Swedish time is open for scientists from all countries (but note that proposals for observations with the SEPIA instrument must have a PI or co-I with a Swedish affiliation). Co-operation with Swedish scientists is encouraged (but proposals will be evaluated solely on scientific merit). Scientists not affiliated with Swedish institutes are informed that it is also possible to apply for ESO time on APEX.

Note that the weather is best during night time and early mornings, which is important to consider for observations at the higher frequencies. Observations of sources closer than 30 degrees from the Sun are not allowed.

Observations will be performed in service mode.

Observers are encouraged to visit APEX to assist in carrying out the service observations. Travel expenses will afterwards be covered by Onsala Space Observatory, through invoicing via the home institute of the observer. Which of the co-authors who are willing to visit APEX should be indicated in the proposal. More information can be given by the Swedish APEX project scientist Per Bergman (per.bergman@chalmers.se).

Telescope:

  • 12 m diameter telescope for mm and sub-mm waves.
  • Location: Llano de Chajnantor, 50 km east of San Pedro de Atacama, northern Chile. Latitude: 23º00'20.8" South, longitude: 67º45'33.0" West. Elevation: 5107 m.

Receivers:

The facility instruments, SHeFI and LABOCA, are available for all users.
 
Partner instruments (see APEX Instrumentation) are available only via cooperation with the instrument PI. The instrument PI must have been contacted before the submission of the proposal, and agreed that it will be possible to carry out the proposed observations. This must be stated in the proposal. This rule applies, e.g., to FLASH+, which is an MPIfR instrument (PI: Rolf Güsten). ArTeMiS is a partner instrument which will be fully available on Swedish time for all users (no need to contact the instrument PI before the submission of the proposal). SEPIA is a partner instrument, and proposals for observations with SEPIA on Swedish time must have a PI or co-I with a Swedish affiliation (no need to contact the instrument PI before the submission of the proposal).
***  SHeFI  ***

The Swedish Heterodyne Facility Instrument (SHeFI) contains three single-pixel receivers mounted in a single cryostat located in the Nasmyth A cabin of APEX:

  • APEX-1: a Single Side Band (SSB) SIS receiver covering 211–270 GHz with SSB receiver temperature Trec around 125 K between 211 and 240 GHz and 190 K between 240 and 270 GHz. APEX-1 can be used also during conditions with PWV>2 mm.
  • APEX-2: a Single Side Band (SSB) SIS receiver covering 270–370 GHz with SSB receiver temperature Trec around 135 K over most of the frequency band (but higher at the highest frequencies).
  • APEX-3: a Double Side Band (DSB) SIS receiver covering 385–500 GHz with DSB receiver temperature Trec of about 100 K.

The available spectrometer is a Fast Fourier Transform Spectrometer consisting of two partially overlapping units, each with a bandwidth of 2.5 GHz, resulting in a total bandwidth of 4 GHz. The units have 32768 spectral channels each, providing a channel separation of 76 kHz.

Please use the online observing time calculator at the APEX web site for observing time estimates, for either On/off observations or On-the-fly observations. (Please note that the calculators might not work with old web browsers.)

***  SEPIA  ***
The SEPIA instrument can house up to three ALMA-type receiver cartridges. It presently houses an ALMA band 5 receiver (159211 GHz) and an ALMA band 9 receiver (600–722 GHz).
- The SEPIA band 5 receiver (159211 GHz) is a dual polarization sideband separating (2SB) receiver. It has two IF outputs (sidebands) per polarization, USB and LSB, 4-8 GHz, in total a 16 GHz IF band. The USB and LSB IF central frequencies, 6 GHz, are separated by 12 GHz. The sideband rejection ratio is >10 dB and 18.5 dB on average. The single-sideband noise temperature of the receiver is below 55 K. At 177 GHz, the beam size is 35 arcsec.
- The SEPIA band 9 receiver (600–722 GHz) is a double sideband (DSB) receiver. Only 4 GHz bandwidth of one of the sidebands is recorded, but in dual polarization. At 660 GHz, the beam size is 9.5 arcsec.
 
The available spectrometer is a Fast Fourier Transform Spectrometer (called XFFTS) with 4 GHz IF bandwidth. For the 2SB receiver of band 5, it covers 4 GHz for each polarisation and for each sideband (i.e., 4x4 GHz in total). For the DSB receiver of band 9, only 4 GHz bandwidth of one of the sidebands is recorded, but in dual polarization. Each 4 GHz band consists of two partially overlapping units, each with a bandwidth of 2.5 GHz, resulting in a total bandwidth of 4 GHz. The 2.5 GHz units have 65536 or 32768 spectral channels each, providing a channel separation of 38 kHz or 76 kHz.
The offered observing patterns are on-off observations, raster maps, and on-the-fly (OTF) mapping. The data will be taken in either beam-switching or position switching mode.

It is important to consider the atmospheric transmission at the APEX site. Concerning SEPIA band 5, the atmospheric transmission at 183 GHz (water line) is better than 0.3 for pwv < 0.5 mm (pwv = precipitable water vapour). This happens at about 15 % of the total observing time (corresponding to ~50 days per year). At frequencies < 174 GHz and > 192 GHz, the atmospheric transmission is better than 0.8 for pwv < 2 mm. Concerning SEPIA band 9, generally, pwv < 0.7 mm conditions are required , though at some frequencies, even better conditions will be required. Note that these good to excellent conditions statistically occur 40 % of the time. The APEX web site provides information on the atmosphere above APEX and the annual variation of the pwv. This figure shows the atmospheric transmission for the band 9 frequencies: ChajnantorAtm.pdf.
 
Please use the online observing time calculator at the APEX web site for observing time estimates, for either On/off observations or On-the-fly observations. (Please note that the calculators might not work with old web browsers.)
 
Note: Proposals for observations with SEPIA must have a PI or co-I with a Swedish affiliation.
 
Technical details for the band 5 receiver can be found in the following publication (which shall be referred to in publications using data obtained with the SEPIA band 5 receiver): Billade, B., et al. “Performance of the First ALMA Band 5 Production Cartridge”, IEEE Trans. Terahertz Science and Technology, Vol. 2, No. 2, March 2012, pp. 208-214. For a technical description of the band 9 receiver, please see the following publication: Baryshev, A. M., et al. "The ALMA Band 9 receiver. Design, construction, characterization and first light", Astronomy & Astrophysics, Vol 577, A12 (February 2015).
***  LABOCA  ***

LABOCA is a bolometer array camera for the 870 μm (345 GHz) atmospheric window. It has 295 channels arranged in a hexagonal layout consisting of a centre channel and 9 concentric hexagons.

The APEX beamwidth at this wavelength is 18.6 arcsec (FWHM) and the total field of view of LABOCA is 11.4 arcmin. The array is undersampled on the sky; the separation between channels is twice the beam size (36 arcsec).

The mean point-source sensitivity of the channels is 60 mJy s1/2 (for extended sources, the sensitivity is 100 mJy s1/2). Please use the online observing time calculator at the APEX web site for observing time estimates. The calculator assumes 1 mm of precipitable water vapor (pwv), corresponding to a zenith opacity of 0.373.

***  ArTeMiS  ***
ArTeMiS is a bolometer array working simultaneously at 350 and 450 μm, developed by CEA Saclay (France). It is an ESO PI instrument, but (as mentioned above) will be fully available on Swedish time for all users with no need to contact the instrument PI before the submission of the proposal. At 350 μm, the field of view is 4.7' x 2.3' and the number of pixels is 2304. Please use the online observing time calculator at the APEX web site for observing time estimates.
 
Note that there are protected guaranteed time observations for the ArTeMiS consortium of the source M17 (see ESO Guaranteed Time Observations for Period 100).

Proposals for Large Programmes:

It is not possible to propose Larger Programmes (requiring >100 h observing time spread over maximum two years) for this deadline.

Proposal preparation and submission:

Onsala Space Observatory uses the NorthStar system for preparation and submission of both 20 m telescope and APEX proposals. NorthStar is used by several radio and optical observatories.

In NorthStar, information about applicants, instruments, targets, etc., is to be provided "on-line", and the scientific justification is to be prepared "off-line" and uploaded as a pdf file (also target lists can be uploaded). NorthStar then produces one pdf file with all information. NorthStar includes information on how to use it.

The proposal must contain a proper and concise scientific justification including an explanation for how the requested observing time was calculated, in total no more than two A4 pages long (three pages for APEX Large Programme proposals), plus figures and tables if needed (for a total of maximum six pages). Proposers should mention relevant previous observations with Onsala telescopes, and clearly show preliminary results. Observing time estimates should be made using on-line observing time calculators. If observations are for Ph.D. work, this should be stated.

In order to avoid duplicating observations, please check the ESO archive for previous observations.

Further information and useful links:

Published: Wed 04 Sep 2013. Modified: Wed 22 Mar 2017