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Filters

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Approximate wavelengths for filters accepted for the AAVSO International Database

The filters listed below are used in the AAVSO International Database. 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.

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)
 

Filter

AID
abbreviation

Effective
Wavelength (Å)

FWHM (Å)

Approximate wavelengths of photometry filters in the AAVSO International Database (AID)
Johnson U U 3663 650
Johnson B B 4361 890
Johnson V V 5448 840
Cousins R R 6407 1580
Cousins I I 7980 1540
Near-Infrared J J 1.2 microns 1.09-1.41 microns
Near-Infrared H H 1.6 microns 1.48-1.84 microns
Near-Infrared K K 2.2 microns 1.98-2.35 microns
Sloan u SU 3543 3200-3850
Sloan g SG 4770 4010-5500
Sloan r SR 6231 5550-6950
Sloan i SI 7625 6900-8200
Sloan z SZ or Z 9134 8200-
Stromgren u STU 3520 314
Stromgren v STV 4100 170
Stromgren b STB 4688 185
Stromgren y STY 5480 226
Stromgren Hbw STHBW 4890 150
Stromgren Hbn STHBN 4860 30
Optec Wing A MA 7120 110
Optec Wing B MB 7540 110
Optec Wing C (or Wing I) MI 10240 420
DSLR Blue TB  differs by camera, not in use as of 2/2012  
DSLR Green TG  differs by camera  
DSLR Red TR  differs by camera, not in use as of 2/2012  
Clear (unfiltered) reduced to V sequence CV  differs by camera  
Clear (unfiltered) reduced to R sequence CR  differs by camera  
Halpha HA  6563      not in use as of 2/2012  
Halpha_continuum HAC  5400      not in use as of 2/2012 5350-5410
Other O  filter not listed above, must describe in Comments; not in use as of 2/2012  

 

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)
Sloan zugri: Astrodon Sloan filters table; SDSS camera and filters publication (http://www.astro.princeton.edu/PBOOK/camera/camera.htm)
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

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