Welcome to the European ALMA Regional Centre Newsletter!
This Newsletter is a compilation of recent European ALMA Regional Centre Announcement items. Follow the links or visit the European ARC Announcements to read more. In addition to these Announcements the Newsletter informs you about various developments in the ALMA Programme, as well as about ALMA or ALMA-related meetings.
ALMA Cycle 5 successfully started on 1 October 2017. Principal Investigator observations have started with the longest configurations (~16 km). Therafter, the Array will be reconfigured continuously until it reaches the most compact baselines in July 2018. ALMA users may check the configuration schedule and the real-time observing status at any time.
More details on the outcome of the ALMA Cycle 5 review are now available. The highest priority Cycle 5 projects are listed on a dedicated webpage. In addition a full report describes the proposal review process in detail, and presents the proposal statistics and regional distribution, as well as the distribution of proposals across science categories and receiver bands. The report can be downloaded here.
The anticipated configuration schedule for Cycle 5 has been modified from that posted in the Proposer's Guide and the updated schedule is available at the following link: https://almascience.eso.org/news/observing/observing-configuration-schedule. The changes were made to optimise the schedule in response to the pressure from the top-rated proposals in Cycle 5 and the adverse weather at the ALMA site, which affected the configuration schedule at the end of Cycle 4. The most significant change is that Cycle 5 will begin in the configuration C43-10 instead of C43-7, and then move to more compact configurations.
During the last week of September the staff working in all the European ARC nodes had their yearly meeting in Den Dolder (NL) hosted by the Allegro node.
This yearly meeting brings together all the expertise in the network, in a unique occasion that allows us to share our experiences, strengthen our links and discuss past, present and future developments.
We all are looking forward to our next meeting that will be organised by our colleagues at the Czech ARC node.
The final ALMA Band 5 cold cartridge was shipped on 7 November from Europe to Chile, completing the delivery of a total of 73 production receivers. Teams from NOVA, the research school for astronomy in the Netherlands, and from Onsala Space Observatory's Group for Advanced Receiver Development (GARD), worked together with colleagues from ESO to produce the cryogenically cooled Band 5 receivers. Congratulations to everyone involved in reaching this important milestone!
ALMA’s Band 5 covers a range of wavelengths from 1.4 to 1.8 millimetres (frequencies from 163 to 211 GHz), and is particularly useful for detecting water in the local Universe. The receiver band also opens up the possibility of studying complex molecules in star-forming regions and protoplanetary discs, and detecting molecules and atoms in galaxies in the early Universe.
ESO placed the European contract for the cryogenically cooled receivers with NOVA and GARD. The first production-type receivers were built and delivered to ALMA in 2015, when two receivers were used for “first fringes”. The recent shipment of the 73rd and final receiver cold cartridge to Chile means that all cold cartridges and auxiliary equipment have been delivered to ALMA, where they join the warm cartridge assemblies that had already been delivered by the North American ALMA partner.
The remaining work to complete the full deployment of Band 5 at ALMA is now concentrated at the Operations Support Facility, where all the receivers are being integrated and commissioned. So far, this has been done for Band 5 receivers on 49 of the 66 ALMA antennas (the delivery of 73 receivers allows for equipping all the antennas, plus spares). All the 7-m antennas of the Morita array (ACA) have been equipped and observations in Band 5 are scheduled to commence soon. The 12-m antennas will be fully equipped in the coming months and observations will start as planned on 1st March 2018.
Teams from NOVA, the research school for astronomy in the Netherlands (left), and from Onsala Space Observatory's Group for Advanced Receiver Development (GARD, right)
News from the ARC Nodes
From Allegro: WVR Scaling Module
This contribution describes a software package to optimise the application of the WVR solutions for ALMA Observations. Details can be found in Maud et al. 2017 (A&A, 605, 121; arXiv).
The Atacama Large millimetre/sub-millimetre Array (ALMA) makes use of Water Vapour Radiometers (WVR) which monitor the atmospheric water vapour line at 183 GHz along the line-of-sight above each antenna to correct for phase delays introduced by the wet component of the troposphere. Application of WVR derived phase corrections improve image quality and facilitate successful observations in weather conditions that were classically marginal or poor.
The phase fluctuations after WVR application are noticeably reduced, typically by a factor of 2 or more. In drier conditions where the PWV < 1 mm, these corrections are become less significant (factors < 2) as the water content causing phase fluctuation has decreased. At Allegro we have studied the effects of scaling the WVR solutions in an attempt to improve the phases of data taken in dryer, low PWV conditions.
Maud et al. 2017 (A&A, 605, 121; arXiv) examined the Long Baseline Campaign Science Verification data and found that in dry conditions (PWV <1mm) a scaling factor (> 1) applied to the WVR solutions in WVRGCAL can help to reduce the phase fluctuations, improve the coherence of the data and therefore improve the images of the science target. For the tested data the improvements range from 1-2% in most cases, but can be as high as > 5-10%. One explanation for the WVR scaling factor is that the wet and dry air become mixed, such that the scaling accounts for extra delays induced by the dry air, that is not directly measurable.
A link is provided to a PYTHON module package that allows anyone with ALMA data to run the WVR scaling tests to see if any improvements can be made. At present and as detailed in the paper, we expect improvements for long baseline (> 5 km) and high frequency data (> 230 GHz).
The figures below show an example of the plots the module produces to indicate what scaling value is needed and the expect coherence improvements. Please refer to the paper and the module README for more details.
The software is available form the following link: WVR_scaling_module_Sep2017.tar.gz. To run the software the astropy version 1.3.3 and CASA < 5.0 (CASA 4.7.2 is the latest working version) are required.
Left: Tests made using baselines with the reference antenna only; Right: Tests made using all baselines in the array. Tests using all baselines are more robust although are a factor of 5-10 times more time expensive.
From Allegro: Cone Searches for HF/LB projects
ALMA makes it possible for astronomers to observe the mm and sub-mm spectrum with unprecedented sensitivity resolution. As such, this unexplored space requires suitable calibrator sources for each new science target.
Since the first regular observations in the High-Frequency bands (Bands 8, 9 and 10) offered in Cycle 3, the Cone-Searches Team has been performing searches for suitable phase calibrators and check sources for science observations. Around each science target, calibrator candidates have been selected according to the required observational setup. Candidates were observed and their fluxes have been ingested in the ALMA Source Catalogue well before the final observations are performed to ensure a successful calibration afterwards.
In the case of High-Frequency observations the difficulties mainly arise from finding bright enough point-like sources relatively close to the Science Target at those frequencies. After the successful High-Frequency Calibrator Survey Campaign, the Cone-Searches Team has also enroled the Cycle 5 Long-Baseline Calibrator Survey Campaign (the most extended configurations from C43-7 to C43-10, corresponding to maximum baseline length between 3.7 km and 16 km). This has been particularly challenging in the current cycle due to the large number of projects involved. For observations with very long baselines it is particularly important that the sources that are selected as phase-calibrators are not spatially resolved at such high resolutions.
The Cone-Searches Team is composed by members of Allegro node in the Netherlands (Yanett Contreras, MCarmen Toribio and Lizette Guzmán-Ramírez) and staff at JAO (Satoko Takahashi as the coordinator, Akihiko Hirota, Ed Fomalont, Hugo Messias). The Cone-Searches team works in close interaction with the P2G and CalSurvey Teams with the aim to provide the best calibrators.
Upcoming ALMA or ALMA-related Meetings
ALMA Data Processing Workshop 5 – 7 December, Lisbon, Portugal
The Portuguese ALMA CENTER of Expertise (PACE) on behalf of the Institute of Astronomy and Space Sciences, in collaboration with the ESO and the RadioNet consortium (grant agreement No 730562), is glad to announce that an "ALMA Data Processing Workshop" will take place in Lisbon on 5th (afternoon), 6th, and 7th of December.
Workshop on Self-Calibration and Advanced Imaging 11 – 13 December 2017 , Istituto di Radioastronomia Bologna, Italy
The main purpose of this short workshop is to obtain a better understanding of the self-calibration and advanced imaging techniques, in particular on ALMA data. It will be a unique opportunity for the participants, who are expected to be advanced users, to familiarize themselves with these techniques and to discuss about them in an informal way with experts in the field. During the hands-on sessions participants can possibly work on their own datasets, receiving help from the experts and discussing with the other participants. A "backup" dataset will be also made available.
Atacama Large-Aperture Submm/mm Telescope (AtLAST) 17 – 19 January 2018, Garching bei München, Germany
The workshop will be a crucial forum to collect insights and feedback, and commit to a single vision for realising a single dish facility. The programme will cover aspects of the science case driving the telescope and instrument requirements as well as potential telescope concepts.
Submillimetre Single-dish Data Reduction and Array Combination Techniques 15 – 16 March 2018, Garching bei München, Germany
The worshop will cover both line and continuum data, and will consist of introductory lectures followed by hands-on tutorial sessions on ALMA single-dish data reduction in CASA, spectral line reduction of submm data in CLASS, bolometer software for APEX instruments (BoA for LABOCA, Scanarmorphose for ArTeMiS), and the combination of single-dish and interferometry data in CASA.
Radio Interferometry: Methods and Science Starting April 2018, Bonn, Germany
The course will be organized by the German ARC node and offers a hands-on overview of major aspects of radio/mm/submm interferometry for master students, PhD students and senior astronomers. The course is planned to start in April 2018.
Tracing the Flow: Galactic Environments and the Formation of Massive Stars 2 – 6 July 2018, Lake Windermere, UK
With the massive increase in spatial dynamic range and the volume of data now becoming available this meeting will provide the opportunity to assess the current state of our knowledge of massive star formation. In addition, it will help identify the key issues for future work and look forward to the expanding opportunities ALMA will continue to offer in the fields of galactic and extragalactic massive star formation as well as those provided by JWST, ELTs, SKA, ngVLA and other facilities in the future.