SIMBAD references

In this paper, we present a database of class I methanol masers. The compiled information from the available literature provides an open and fast access to the data on class I methanol maser emission, including search, analysis, and visualization of the extensive maser data set. There is information on individual maser components detected with single-dish observations and maser spots obtained from interferometric data. At the moment the database contains information from ∼100 papers, i.e., ∼7500 observations and ∼650 sites of class I methanol masers. Analysis of the data collected in the database shows that the distribution of class I methanol maser sources is similar to that of class II methanol masers. They are mostly found in the molecular ring, where the majority of the OB stars are located. The difference between class I and II distributions is the presence of many class I methanol masers in the nuclear disk region (central molecular zone). Access to the class I methanol maser database is available online at http://maserdb.net.