LOFAR Newsletters June 2017

Previous LOFAR newsletters are collected here.




A.   Deadlines

- The Cycle 9 proposal submission deadline will be on Wednesday, 13 September 2017, 12 UT (noon). The proposal call will be distributed in early July.

B.   Documentation

- The LOFAR web pages on the ASTRON website have been restructured. The new structure will make information easier to find.

- A public LOFAR slides repository is now available here. The repository collects all slides of LOFAR technical and scientific updates presented at LOFAR Status Meetings (LSMs), LOFAR Science Conferences, LOFAR Schools and Users Meetings. Therefore, the repository provides the community with a comprehensive and up to date overview of the status of LOFAR and of its scientific productivity. The repository also gives the important opportunity to directly upload the LOFAR-related slides presented by users at other conferences and meetings. We solicit all users to give their contribution, as to do so will establish this repository as an important tool for the dissemination of LOFAR results.

- Version 21.0 f the LOFAR Imaging Cookbook has been released on 20 June. In can be found here. Particularly relevant to new users is the addition to Chapter 10 of more tutorials describing the full path of manually reducing LOFAR data (from data inspection to imaging) using the latest tools available.

C.   Events

- The conference ‘The Broad Impact of Low Frequency Observing' took place between 19-23 June, in Bologna, Italy. The programme provided a comprehensive overview of the versatility and state-of-the-art technical capabilities available at low frequencies. The meeting was an important opportunity to discuss the planned upgrades to LOFAR and the other current facilities, looking ahead also to how these will complement the SKA-low in the years to come. All presentations are available at the conference website and will soon become available at the LOFAR Slides Repository.

- The 4th LOFAR Users Meeting took place on 23 June, in Bologna (Italy). The Radio Observatory answered questions from users and gathered a lot of important feedback that will be used to improve the user experience during the coming months. All presentations are available here and will soon become available at the LOFAR Slides Repository.

D.   Data

- Data taken between December 9, 2016 and June 6, 2017 have an extra delay of 1 microsecond on baselines involving DE601. The issue affects only interferometric observations using the Cobalt correlator. More details on the impact on the data and possible solutions are given here. A direct notification to all affected PIs will be distributed soon.

- It has been discovered that the HBA antenna positions of DE605 stored in the system were slightly incorrect and have been fixed on 19 June. A proper assessment of the effects on the data and possible solutions is in progress. The affected PIs will be informed as soon as possible.

- High amplitudes caused by payload errors are seen in 8-bit mode in sub bands in the 3rd quartile for baselines involving SE607. The Radio Observatory is currently investigating possible solutions.

- Jülich has experienced data loss during two periods: from October 3 until October 5, 2016 and from April 1 until May 15 2017. During these periods, a limited number of files ingested by the Radio Observatory did not reach the Juelich tapes and were therefore lost. All affected PIs have been notified, while necessary re-observing has been already planned.

E.    Miscellanea

- A major CEP3 system upgrade was performed between 15 May - 5 June. The cluster's operating system was upgraded from Ubuntu 12.04.4 LTS to Centos 7.3, a more modern and better maintainable system for the coming years. Newer system libraries are now available to facilitate the support of software requiring modern compilers and libraries. The new system will allow users to run self-prepared docker images or (in the future) to use one of the standard LOFAR images. This makes users less dependent on what software is available on CEP3. For more details, please visit the Wiki documentation available here.

- In the autumn, Redmine will be replaced by JIRA. This new ticketing system which is hosted at https://support.astron.nl/rohelpdesk will provide helpdesk functionality to manage user's support now normally handled through the SOS e-mail address. Documentation and FAQ pages will provide the most up to date status about the system and procedures and help users with dealing with common issues.


Array status:


- 38 stations operational in the Netherlands: 24 core and 14 remote stations.

- 12 international stations operational: DE601, DE602, DE603, DE604, DE605, FR606, SE607, UK608, DE609, PL610, PL611, PL612.

- A new LOFAR station (IE613) is being built on the grounds of Birr Castle, located centrally in Ireland. Expected adoption in operations: second half 2017.

- The overview of non-operational antenna elements for LBA and HBA is available here

-  Station calibration:

o   The calibration tables for HBA-mid (mode 6) have been updated on the remote and international stations in early May. The update of HBA-mid calibration tables for the core stations awaits the calculation of Cobalt clock delays.

o   Investigations are ongoing to improve the quality of LBA calibration of three particular remote stations (RS210, RS310, RS407).

o   Calibration tables for LBA Sparse Odd and LBA Sparse Even are installed on all stations. While there are indications that phase alignment is achieved at station level, interferometric test observations with the full array are still being investigated.


Observing System Status:


- Rebooting of COBALT nodes as well as data loss for high data rate observations on CEP4 have caused observing failures and delays in the exploitation of the Cycle 7 & 8 observing. While the causes of the problems are still under investigation, observations/pipelines are planned so to minimize occurrences.


Software development status (J. Annyas):


- With the help of Dell, the CEP4 system configuration is changed step by step to solve data losses and node crashes. After each step, thorough testing is needed to determine the actual results. This is a time consuming process, but the gains so far are better system tuning and experience gain for our system administrators. If this fails, then we will have to modify the application to avoid the conditions that trigger the crashes and data loss.

- Related to the Responsive Telescope project, LOFAR can now be triggered when there is no current measurement. The next step will be interrupting an observation. 

- NenuFAR is being set up in local mode


MSSS Status (J. Broderick & G. Heald)


- Mosaicking and associated quality control work continues. 45-arcsec resolution data products for survey regions > Dec +35 deg. are expected to be available to the MSSS team by the end of this month. 

- An MSSS paper was recently accepted for publication: "The Scaling Relation between AGN Cavity Power and Radio Luminosity at Low Radio Frequencies", Georgi Kokotanekov et al., A&A, in press (arXiv:1706.00225).

- An update on MSSS progress was given at the 'The Broad Impact of Low Frequency Observing' conference in Bologna two weeks ago: http://www.astron.nl/lowfrequencyobserving2017/Documents/Tuesday/LFO2017...


Observing Programmes


- Cycle 8 observing programme: 15% complete. The observing schedule can be found here.

- Cycle 7 observing programme: 89% complete. The rest is being observed with second priority during Cycle 8.


CEP news:


-       CEP4

  • See above

-       CEP3:

  • Cluster info (with updated documentation) and schedule available here.
  • Monitoring of node usage is active. Statistics will be used to evaluate requests for extensions.


Calendar next LOFAR activities:


Note: the following events are marked on an online calendar that is available here.

-       NAM 2017, 02-06 July 2017. Special LOFAR session: afternoon 6 July.

-       Next LSM's: 19/07, 23/08

(all presentations given at the LSM and video recordings are available here).

-       Next Stop days: 04/07, 01/08

-       Next software roll outs: 10/07, 11/09

-       Next LOFAR bulletin: August 2017

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