The AAVSO Argelander Society

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Soon after Gary Walker became an Arglender Society member in 2015, Eduard Schoenfeld, another observer, had the chance to interview Gary and asked, "You've been a member for a long time. Has the change and growth of the AAVSO impacted your view of the importance of giving?" Gary answered,


Argelander members to date:


About Friedrich Argelander

Friedrich Argelander was the first astronomer to begin a careful study of variable stars. At the time, only a handful of variables were known, and he was responsible for introducing the modern system of naming them using the capital letters R-Z. It was believed that variability was a rare phenomenon and that this would provide plenty of names for the variables yet to be discovered. In a few years this proved inadequate and the naming system was extended to double letters, and then a numbering system. Today, tens of thousands of variable stars are cataloged, with more being discovered all the time.

The “Argelander Step Method” is a visual method of estimating the magnitude of a variable star. It involves comparing the variable with comparison stars of known constant magnitude, and assigning a step value that reflects the brightness of the variable as distinguished from that of the comparison star. The magnitude of the variable can then be calculated from the known magnitudes of the comparisons. This is very similar in practice to methods still used today by visual observers of variable stars.









Argelander is probably best known for the Bonner Dorchmusterung, the largest and most comprehensive of the pre-photographic star catalogs. He began mapping the exact positions of the stars in the northern sky in 1852, a monumental task before the use of photographic plates. When finally completed in 1863, it listed the positions of 324,198 stars down to ninth magnitude.