Filters

Approximate wavelengths for filters accepted for the AAVSO International Database

The filters listed below are used in the AAVSO International Database [1]. For your reference, the approximate effective wavelength is given as well as the Full Width Half Maximum. These filters may be used when submitting observations to the AAVSO via WebObs [2].

Numbers are in Ångstroms unless otherwise indicated. FWHM = Full Width Half Maximum (gives the approximate width of the coverage; e.g., Johnson U is approximately 650 Ångstroms wide centered on 3663 Å; equivalent to the 50% transmission value)
 

Note: The effective wavelength values for the Sloan filters are from the SDSS filters table. The Sloan FWHM values are from the Astrodon filters information table.

References
Johnson UBV: Bessell, Ann. Rev. Astron. Astrophys., 43 (2005)
Cousins RI: Bessell, Ann. Rev. Astron. Astrophys., 43 (2005)
JHK: JHK filter table on Marco Gullieuszik webpage on ESO work (http://web.oapd.inaf.it/gullieuszik/research.php [3])
Sloan zugri: Astrodon Sloan filters table; SDSS camera and filters publication (http://www.astro.princeton.edu/PBOOK/camera/camera.htm [4])
Stromgren uvby: Bessell, Ann. Rev. Astron. Astrophys., 43 (2005)
Wing ABC/I: Wing, JAAVSO, 21, 1, 42 (1992)
Halpha_continuum: Baader Solar Continuum Filter information