Optical Filters

 

A suite of broad and narrow band optical filters, covering nearly all research needs in imaging objects of the local universe, is available at Skinakas Observatory. In the following we present the list of those filters and their characteristics. The filter transmission curves, where available, can be displayed by selecting the hyperlink under the corresponding filter name.


Standard Johnson-Cousins filters

Type Central Wavelength (Å) FWHM (Å) Peak Transmission (%) Diameter (mm) Thickness (mm) Manufacturer
U 3640 320 63 75.9   Custom Scientific
B 4350 980 72 75.9 8.9 Custom Scientific
V 5380 980 88 75.9 8.9 Custom Scientific
R 6300 1180 82 76.0 9.1 Custom Scientific
I 8940 3370 96 75.9 8.9 Custom Scientific

 

 

List of Strömgren filters

Type Central Wavelength (Å) FWHM (Å) Peak Transmission (%) Diameter (mm) Thickness (mm) Manufacturer
u 3500 330 57     Custom Scient.
v 4110 170 67     Custom Scient.
b 4685 183 83     Custom Scient.
y 5493 235 84     Custom Scient.
Hβ wide 4890 145 80 76 10.2 Omega Optical
Hβ narrow 4869 32 80 75.8 6 Spectrofilm.

 

 

List of interference filters

Type Central Wavelength (Å) FWHM (Å) Peak Trans. (%) RI Diameter (mm) Thickness (mm) Weight (gr) Manufacturer
[OII]3727 3727 25 60 2       Custom Sc.
[OIII]4363 4363 10 35 2 75.8 6.6 80 Omega
HeII4686 4687 20 46 2 75.8 5.8 70 Omega
Hβ4861 4864 28 65 2.1 76 10.2 105 Spectrofilm
[OIII]5007 5010 28 63 2.1 76 10.2 105 Spectrofilm
[OIII]5007 5007 (April 2013) 25 52 2.1 76.1 5.5   Spectrofilm
[NII]5755 5755 10 52 2 75.8 6.6 80 Omega
HeI5876 5877 20 54 2 75.8 5.8 70 Omega
Hα6563 6563 10 52 2 75.8 6.6 80 Omega
Hα+[NII] 6575 20 48 2 75.8 5.8 70 Omega
Hα+[NII] 6570 75 80 2.1 76 10.5 105 Spectrofilm
[NII] 6584 20 60 2  75.8  5  - Omega
[SII]6716 6716 10 47 2 75.8 6.6 80 Omega
[SII]6720 6720 27 80 2.1 76 6.3 70 Spectrofilm
[SII]6731 6731 10 57 2 75.8 6.6 80 Omega
[SII]6735 6735 30 48 2 76 5.75 70 Omega
[SIII] 9069 20 70 2  75.8  - Omega
Continuum 6096 134 - - 76 6.5 70 Spectrofilm
Notes
Peak Trans: Peak Filter Transmission
RI: Filter Refraction Index