The AAVSO's archive of times of maxima and minima of long period variables is almost as old as the AAVSO itself, and we are giving these data new life by re-releasing them to the community in electronic form after a long hiatus.
Dates and times of maxima and minima of long period variables have been computed from observations submitted by AAVSO observers since the founding of the organization, and the resulting tables of maxima and minima were published first in the Annals of Harvard College Observatory, and then in two specially-prepared publications. The data from 1900 to 1975 were published in three major volumes: Harvard Annals, Volume 79, Part 2 by Leon Campbell (1926); Studies of Long-Period Variables by Campbell (1954); and Maxima and Minima of Long Period Variables, 1949-1975 by Mattei, Mayall, and Waagen (1990). Since that volume was released, no new data have been formally published. The times of maxima and minima continued to be collected as preparation for our annual AAVSO Bulletin by Margaret Mayall, Janet Mattei, and Elizabeth Waagen, but the measurements were never formally put in print. The data were available electronically on the web up through 2002, but have been offline since that time. As part of our program to make archival data online, the AAVSO has carried out a new release of these data spanning more than a century from 1900 to 2008.
At the present time, we are releasing the data "as is" and as a result the database is heterogeneous. From 1900 to 1990, data have both a time and a magnitude of maximum for each observed cycle. From 1990 to the present, we are currently publishing times of maximum and minimum only. In the near future, we are planning to update these data to include magnitude information that will be automatically derived from observations in the AID. Future additions to the database will depend upon the available time and resources at the AAVSO.
For more information on the Maxima and Minima project, please visit our webpage.