LOFAR Newsletters April 2017

Previous LOFAR newsletters are collected here.




- The Conference ‘The Broad Impact of Low Frequency observing' will take place between 19-23 June 2017 in Bologna (Italy). It will run from Monday morning, 9 am till Friday, lunchtime. On Friday afternoon, we will hold the 4th LOFAR Users Meeting, at the same venue. More details are given here. Late registration will be possible till 15 May. The final programs will be advertised at the beginning of May.

- Since 7 May 2018, the Science Operations & Support (SOS) group of the Radio Observatory of Astron has adopted a new ticketing system through the RO helpdesk which is hosted at https://support.astron.nl/rohelpdesk

- The software Support group of the Radio Observatory of ASTRON has been renamed Software Development and Operational Support (SDOS). This is to emphasize that development of new functionality and system and network administration of LOFAR and WSRT are also competence of the group.

- At the Cycle 8 proposal submission deadline on 8 March 35 regular proposals have been received. The oversubscription factors for observing and processing time categories are 2.8 and 1.3, respectively. The PC has distributed 1460 observing and 1554.5 processing hours. Cycle 8 will start on 15 May.

- A major CEP3 system upgrade is planned for the period 15-31 May 2017. Among other things, the upgrade will allow easier maintenance of the cluster in the future and more up-to-date tools and libraries to be used. Access to the cluster will not be possible during the aforementioned period. The upgrade plan has been finalized. Further details will be shared with the affected users in the coming few days.

- Redmine will be replaced by a new ticketing system. Various options are currently being tested. The new tool will be adopted also by Science Operations & Support to handle user support.


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 completion: second half 2017.

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

- Station calibration:

  • At the end of December, tables for modes 5 and 7 were updated on international and remote stations. Mode 6 data have since then been acquired and reduced and will be installed in the next weeks. Once COBALT delays are calculated, this HBA update will be extended to the core stations. 
  • In March, LBA OUTER tables were updated on the Dutch stations and new LBA tables for the international stations are ready for installation.
  • Both ODD and EVEN tables for LBA SPARSE have been installed on the Dutch array.


Observing System Status:


- Rebooting of COBALT nodes as well as data loss for high data rate observations on CEP4 have caused delays in the exploitation of the Cycle 7 observing programme during the past two months. While the cause of the data losses is still under investigation, the COBALT nodes crashes were solved by a kernel upgrade.

- As a result of a failure in the electrical power system, a major disruption has occurred at the Poznan LTA site in March. This caused LOFAR LTA services at the site to be unavailable for several weeks. Activities to bring the systems back to operation took place in close collaboration between teams from PSNC, ASTRON, and FZJ and with support from the dCache development team. There has not been any loss of data and the databases have been fully reconstructed to bring operations back to normal since the beginning of April.     


CITT Status (E. Orru' & T. J. Dijkema)


- DPPP: a direction dependent solver is being tested and further developed by the CITT in collaboration with A. Offringa and M. Mevius. This solver allows, while solving, to constrain the data. For instance applying a constraint on the TEC (e.g 1/nu), a constraint that forces all the data from CORE stations to have the same TEC value,  etc. In this framework also a phase screen is being developed in order to have a gradual phase variation over the field of view.     

- WSClean now has the functionality to use Image Domain Gridding (IDG) when IDG is available. Successful tests have been run on a GPU machine of CEP4. An image of 30.000 x 30.000 pixels has been produced in ~ 2h. Still some glitches have to be solved before IDG can be released.

- Factor, the direction dependent pipeline for HBA data, is now at release 1.2. On the master branch, development continues on features like using automatic masking. An archiving/unarchiving script is being tested at the moment of writing. There is also active discussion about which final data products to ingest into the LTA.

Software development status (J. Annyas):


- As mentioned above, heavy production disturbances by COBALT crashes and CEP4 data loss were experienced during the past two months. Time consuming debugging leads to solutions, which have solved parts of the issues. 

- The responsive telescope project is more than 50% done.

-  User Ingest is planned for the next rollout.


MSSS Status (J. Broderick & G. Heald)


- The MSSS team continues to make strong progress towards the planned release of HBA data products at 45 arcsec angular resolution (i.e. to produce a low-frequency counterpart to the 1.4 GHz NVSS). Most of the individual fields above a declination of 35 degrees have now been reimaged on CEP3. In parallel with ongoing work that is yielding an updated set of mosaics with refined bootstrapping of the absolute flux density scale, the MSSS team is conducting numerous quality control tests to ensure that the final catalog is of high quality. Initial results are very positive, with many improvements over the previous lower-resolution internal release. After further interpretation and verification in the coming weeks, they will expand their effort to the more southerly regions of the survey. MSSS science projects are also continuing with the new mosaics and associated subcatalogs. A significant update will be given at 'The Broad Impact of Low Frequency Observing' conference in Bologna in June.


Observing Programmes


- Cycle 7 observing programme: 78% complete. The observing schedule can be found here.

- Cycle 6 observing programme: 93% complete. The rest is being observed with second priority during Cycle 7.


CEP news:


-       CEP4

  • The performance of the cluster has been monitored during an intense observing campaign at the end of March. The test was designed to assess what observing/processing efficiencies could be supported by the system. Unfortunately, node reboots as well as data loss issues affected the campaign, which will have to be repeated once all issues are solved.
  • Characterization of the various processing pipelines supported by the Radio Observatory has been completed. The results are available here.

-       CEP3:

  • Cluster info 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.


-       The Broad Impact of Low Frequency observing': 19-23 June 2017, Bologna (Italy).

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

-       Next LSM's: 03/05, 31/05, 19/07

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

-       Next Stop days: 02/05, 06/06, 04/07

-       Next software roll outs: 08/05, 10/07

-       Next LOFAR bulletin: June 2017

Design: Kuenst.    Development: Dripl.    © 2022 ASTRON