Skip to main content


The membership database is currently undergoing upgrading/testing. Web functions that involve an interface with the member database (webobs, etc.) may experience intermittent problems. We hope to have this issue resolved within 24 hours (by 5pm Eastern Time on October 1st or 12:00 UT). Thank you for your patience.

Comments on the UBV Photometric System’s Defining Standard Stars


Arlo U. Landolt

Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803

Received August 2, 2013; accepted August 6, 2013


The purpose of this paper is to call the observing community’s attention to the re-affirmation that a majority, 80 percent, of the basic UBV standard stars either are suspected or known variable stars. The elucidation of these stars’ variability characteristics in exquisite detail is a task for which AAVSO observers are eminently qualified.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484