Intensity, luminous/infrared

By definition, photometers do not respond to radiation in the infrared or the ultraviolet (Fig. 4-4a). They are light meters in the sense that they mimic human vision that is, they respond to photons in the visible region, similar to the light meter on a camera. A candle is a unit of luminous intensity, originally based on a standard candle or lamp. The current international unit is called a candela (sometimes still referred to as a candle ), which was previously defined as the total light intensity of 1.67 mm2 of a blackbody radiator (one that radiates maximally) at the melting temperature of pure platinum (2042 K). In 1979 the candela was redefined as the luminous intensity of a monochromatic source with a frequency of 5.40 x 1014 cycles s-1 (A, of 555 nm) emitting 0.01840 Js-1 or 0.01840 W (1.464 mW steradian-1, where W is the abbreviation for watt and steradian... 

A.S. Gouveia-Neto, E.B. da Costa, L.A. Bueno, S.J.L. Ribeiro, Intense red upconversion emission in infrared excited holmium-doped PbGe03-PbF2-CdF2 transparent glass ceramic, /. Lumin., 110, 79-84 (2004). 

R. Predmore, P. Wannier and myself. In particular, the luminous northern source observed by Emerson, Jennings, and Moorwood (1973) has no counterpart in the radio continuum maps, but instead is associated with an intense, extended cloud of molecular gas as evidenced by the CO emission. NGC 633 is a region where I hope future detailed studies of infrared and molecular emission can help pin down the interrelationship. 

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