THE B(J)RI PHOTOMETRIC SYSTEM

The BjRI photometric system was motivated by a need for a set of wide filters for deep CCD imaging in the 0.35-1 mu m wavelength range, as well as the need to connect CCD photometry in the blue with the extensive photographic survey photometry done on blue plates. The Bj CCD system is similar to the J* (Kodak IIIa-J plus GG385) system widely used in photographic surveys. The filters avoid bright night sky emission lines, while maximizing bandpass and transmission. Imaging and photometry of very faint objects to a surface brightness of 30 magnitudes per square arcsecond in less than several hours cumulative exposure time requires a special wideband filter system, together with high-efficiency CCDs on large telescopes. This paper describes the definition of the BjRI system, calibration of standard stars, and transformations to and from the BVR(c)I(c) photometric system. Photometric data on extreme M-dwarfs and red giant stars in this new filter system are also presented.