Photometric Accuracy of the Xinglong 80cm Tsinghua-NOAC Telescope(TNT)

In this paper, the photometric accuracy of the Xinglong 80cm TNT is studied.The equation to transform observed magnitudes to the standard UBVRI system are established by observing a set of Landolt's standard stars, and the relations between white band and R band is discussed.It is shown that the TNT photometric system is very close to the standard Johnson system.Its white band and R band are also very close.Meanwhile, the sky-brightness values at Xinglong are measured.