different filters thay may also be used to produce false color images. Common filters are often used with the Hubble Space Telescope, forming the so-called HST-pallet, with colors assigned as such: Red = S-II; Green = H-alpha; Blue = O-III. These filters are commonly specified with a second figure in nm, which refers to how wide a band is passed, which may cause it to exclude or include other lines. For example, H-alpha at 656 nm, may pick up N-II (at 658–654 nm), some filters will block most of the N-II if they are 3 nm wide. Commonly used lines / filters are: H-Alpha Hα / Ha (656 nm) from the Balmer series is emitted by HII Regions and is one of the stronger sources. H-Beta Hβ / Hb (486 nm) from the Balmer series is visible from stronger sources. O-III (496 nm and 501 nm) filters allow for both of the Oxygen-III lines to pass through. This is strong in many Emission nebulae. S-II (672 nm) filters show the Sulfur-II line. Less common lines/filters: He-II (468 nm) He-I: (587 nm) O-I: (630 nm) Ar-III: (713 nm) CA-II Ca-K/Ca-H: (393 and 396 nm) For solar observing, shows the sun with the K and H Fraunhofer lines N-II (658 nm and 654 nm) Often included in wider H-alpha filters Methane (889 nm) allowing clouds to be seen on the gas giants, Venus and (with filter) the Sun. Ultra-High Contrast filters Known commonly as UHC filters, these filters consist of things which allow multiple strong common emission lines to pass through, which also has the effect of the similar Light Pollution Reduction filters (see below) of blocking most light sources. The UHC filters range from 484 to 506 nm. It transmits both the O-III and H-beta spectral lines, blocks a large fraction of light pollution, and brings the details of planetary nebula and most of emission nebulae under a dark sky. Broadband The broadband, or light pollution reduction (LPR), filters are designed to block the Sodium and Mercury vapor light, and also block natural skyglow such as the auroral light. This allows observing nebulae from the city and light polluted skies. Broadband filters differ from narrowband with the range of wavelengths transmission. LED lighting is more broadband so it is not blocked, although white LEDs have a considerably lower output around 480 nm, which is close to O III and H-beta wavelength.