German ALMA Regional Centre (ARC) Node

The Atacama Large Millimeter/Submillimeter Array (ALMA) is a revolutionary interferometer for mm and submm astronomy in the Atacama desert in Northern Chile. It is operated by a global collaboration between Europe (ESO), North America (NRAO) and East Asia (NAOJ), in cooperation with Chile. The interface between ALMA and the user communities is provided by three ALMA Regional Centres (ARCs) in Europe, North America and East Asia.

The European ARC (EU ARC) is organized as a coordinated network with a central node at ESO Headquarters in Garching bei München and regional nodes located in Bologna(I), Bonn/Cologne(D), Grenoble(F), Leiden(NL), Manchester(GB), Ondrejov(CZ), and Onsala(S). The concept and the implementation of the EU ARC network has been described in an article in the ESO Messenger (Hatziminaoglou et al. 2015, Msngr. 162, 24).

The German ARC node is a collaboration of the universities of Bonn and Cologne. Its headquarters are located at the Argelander-Institut für Astronomie in Bonn. The German ARC node provides services to ALMA operations, the local astronomical community and the general public:

Newsletters and Announcements

Recent News

I-TRAIN with the European ARC Network: events in the autumn

[last update: 14 October 2021]

The European ARC Network is resuming the online training series of I-TRAIN. In the autumn we have scheduled tutorials on software tools to work with ALMA data as well as solar observations with ALMA.

Training sessions this fall:
  • I-TRAIN #8: ALminer, for mining the ALMA Archive (30 September 2021) - link to announcement
  • I-TRAIN #9: LineStacker, for stacking spectral lines (15 October 2021) - link to announcement
  • I-TRAIN #10: Solar observations with ALMA (19 November 2021)
  • I-TRAIN #11: STATCONT, for statistical continuum determination (10 December 2021)
More details on these and previous sessions can be found on the I-TRAIN homepage.

New training opportunity: Introduction to Radio Astronomy

[15 September 2021]

The German ARC node in cooperation with the University of Bonn offers an introduction to radio astronomy for students, postdocs and more senior astronomers. The course highlights various hot science topics currently pursued in radio astronomy, reviews the physical and mathematical foundations of modern radio astronomy and offers a wide range of practical advice from experienced observational radio astronomers. In addition, expert guest lecturers present the latest state of the art in receiver technology and backend development.

For more information, please go to the course homepage and/or contact us at

ALMA Cycle 8 2021 Supplemental Call for Proposals now OPEN

[08 September 2021]

The Joint ALMA Observatory (JAO) is now accepting observing proposals for the Atacama Compact Array (ACA) in stand-alone mode. A minimum of 1500 hours will be allocated each on the 7-m Array and the Total Power Array to proposals submitted at this Call. Proposals wih targets that can be observed in the LST range 20h to 10h are particularly encouraged. The deadline will be 15:00 UT on Wednesday 6 October 2021.

Instructions on how to submit proposals can be found on the Cycle 8 Supplemental Call web page. Proposals submitted in the Supplemental Call will be peer reviewed and each proposal team selects a designated reviewer to participate in the review process. Full details on the offered capabilities, the submission and the review process can be found in the Supplemental Call documentation.

Please note that Supplemental Call proposal submission server will not be available for a few hours on September 27 because of scheduled maintenance. The precise downtimes will be noted on the Science Portal.

ALMA Cycle 7 Science Observations Status Update

[07 September 2021]

PI science observations are continuing with the 12-m and Morita Arrays. As reported in the previous status update on 15 July, there was a delay in the antenna configuration schedule due to the bad weather since May in addition to the impact from the COVID-19 pandemic. There were no further delays since then, and the relocation to the hybrid C43-9/10 configuration was completed on 1 September, 2021. All C43-10 projects in the observing queue are expected to meet the beam criteria when observed in this hybrid configuration. ALMA will stay in the C43-9/10 configuration for approximately 2 weeks, enabling the highest angular resolution observations in Cycle 7. The configuration will then move back to C43-8, aiming for a smooth transition to the start of the Cycle 8 2021 on 1 October, 2021.

The ALMA Regional Centers continue to provide support to all ALMA users. If you have any questions, comments or concerns, please contact your local node or the ALMA Helpdesk.

ALMA Cycle 8 2021 Supplemental Call Pre-Announcement

[23 August 2021]

The Cycle 8 Supplemental Call for Proposals is anticipated to open at 15:00 UT on 8 September 2021 with a proposal deadline of 15:00 UT on 6 October 2021. ALMA expects to allocate a minimum of 1500 h of observing time on the ACA in the Supplemental Call. Proposals for sources in an LST range of 20 to 10 h are particularly encouraged. Preliminary information can be found here. Complete details of the Supplemental Call will be published on 8 September 2021.

Report on the ALMA Cycle 8 2021 Proposal Review

[20 August 2021]

A detailed report on the outcome of the ALMA Cycle 8 2021 Proposal Review Process is now available here (pdf). The report includes the proposal review process, proposal statistics and regional distributions, as well as the proposal distribution across science categories and receiver bands.

The highest priority Cycle 8 2021 projects are listed here.

Update on the amplitude calibration issue affecting some ALMA data

[last update: 11 August 2021]

After the discovery of a visibility amplitude calibration error that affects fields containing strong astronomical emission (see news item below), work on correcting the affected Cycle 7 interferometric datasets has begun.
  • For all affected datasets with a >10% flux scale offset that have yet to be delivered, including those that will be observed in the remainder of Cycle 7 and in Cycle 8 2021, ALMA will apply a renormalization correction during data processing to correctly scale the amplitude calibration before being sent to PIs.
  • For affected datasets with flux scale offsets >2% but <10%, ALMA will provide renormalized data on request from the PI as needed.
  • For affected data in the ALMA Archive, an investigation is underway and plans will be described in a future announcement.
Full details of the issue and the renormalization process are given in this Knowledgebase article.

In case of questions, comments of concerns, please do not hesitate to contact your local ARC node via the ALMA Helpdesk.

ALMA Science Operations Update

[last update: 11 August 2021]

At the end on May and in mid-June, Cycle 7 PI science observations have been interrupted by snowstorms. Combined with pandemic conditions affecting maximum staffing levels at the site, this led to a delay in reaching the 12-m Array C43-7 configuration. Unfortunately, the delay has an impact on the configuration schedule for the remainder of Cycle 7. Having reached the C43-8 configuration in early August, it is planned to move into a hybrid C43-9/10 configuration by early September. All C43-10 projects in the observing queue are expected to meet the beam criteria if observed in this hybrid C43-9/10 configuration.

Cycle 8 2021 science observations, which are foreseen to start on 1 October in the C43-8 configuration, are not affected by the revised configuration schedule.

Status updates will continue to be posted in the ALMA Science Portal and on this webpage on a regular basis.

Update on operations at the German ARC node

[last update: 21 June 2021]

While the decreasing infection rates throughout Germany give hope for more face-to-face interaction in the coming months, the staff of the German ARC node continues to provide all services of an ARC node including user support and training by means of remote computing, emails and video-conferencing. Recent community events and user support include proposal preparation support in March/April via video tutorials, an online community meeting and one-on-one video chats as well as the ongoing hands-on training in radio interferometric data reduction, from the basic principles of radio interferometry to practical help with calibration and imaging of ALMA data (April to July).

While meeting in person is still discouraged, ALMA users are very welcome to contact the staff via email or via the helpdesk. Consultation and practical help via video conference systems can be arranged on short notice as well as access to the computing infrastructure for the efficient reduction and analysis of ALMA data.

Amplitude calibration issue affecting some ALMA data

[last update: 15 June 2021]

A visibility amplitude calibration error that affects fields containing strong astronomical emission has been discovered in ALMA interferometer observations up to and including Cycle 7. This calibration scaling error originates in the combined effect of correlator spectral normalization and Tsys calibration and affects both 12-m Array and Atacama Compact Array observations. The effect of this amplitude scaling error is most notable for observations of strong, relatively narrow spectral lines, typically related to Galactic ISM and Galactic star formation (e.g., molecular lines, masers, etc.). Full technical details of the issue can be found in this Knowledgebase article

In some cases this amplitude scaling error can exceed the nominal absolute flux calibration accuracy quoted in the ALMA Technical Handbook. Affected datasets that have not yet been delivered, will be processed with a renormalization correction to correctly scale the amplitude calibration before being sent to PIs. For affected data in the ALMA Archive, an investigation is underway and plans will be described in a future announcement.

We regret any inconvenience that may arise from this issue. If you have any questions, comments or concerns, please contact your local ALMA Regional Center via the ALMA Helpdesk at

News archive