Dear colleagues,

As you are probably already aware, this year A&A celebrated its 50th anniversary. Over the past half-century, the Board of Directors and the Editors of A&A have been doing their best to shape A&A from a collection of several national journals into an internationally respected journal of high scientific quality. Professional astronomers from all over the world now choose A&A to communicate their scientific findings to their peers in the form of nearly 2000 papers every year. As a result, in 2018 the journal reached a JCR Impact Factor of 6.209, which is higher than those of other well-known astronomy journals with much longer histories.

Recently, Google Inc. also started releasing scientific journal rankings, including astronomical ones, by using the Google Scholar records of individual scientists as input. The JCR, Scopus, and NASA/ADS publication statistics use bibliographic data provided by journals that are collected and analyzed in a supervised manner. Conversely, Google Scholar data are automatically collected by Google, which searches the web using opaque proprietary algorithms. This provides updated values on a daily basis; however, there are very limited provisions for validation and robustness.

As several astronomers with Google Scholar profiles notified us in late March 2019, an error in Google software resulted in undercounting the citations for a large fraction of A&A’s papers by an order of magnitude. This had a serious impact on all of Google’s bibliometric indices (e.g., total citations, h-index, etc.) for nearly all authors at A&A.

The Chief Editor of A&A and EDPS, our publisher, contacted Google, who acknowledged their error and promised to remedy the situation. In order to correct the error, Google needs to fully rebuild their master index, which is a major process that is typically performed twice a year. Unfortunately, Google nonetheless proceeded to release their journal ranking in mid-July 2019 for 2019, presumably before they rebuilt the index. This resulted in a low placement on Google for A&A, which is completely inconsistent with both the JCR rankings and the numbers extracted from the public ADS database.

The Executive Committee of the Board of Directors of A&A and the Editors are fully aware that this unfortunate event is a genuine inconvenience to A&A authors since it creates an unfair perception that their published work has not been recognized by the community. Moreover, Google Scholar indices are often reported in CVs and application materials. This puts some colleagues in a precarious situation as the values they reported from Google indices, that pre-date the error, appear to be invalid.

We would like to ensure our colleagues who have selected A&A as their preferred astronomy journal that A&A and EDPS are following the situation very closely. We are in regular contact with Google Inc., and in parallel we are exploring our other options to convince the company to act and remedy the situation in a timely manner.

© ESO 2019