Steel columns are connected via bolts and cast-in plate and will be welded after calibration.
钢柱通过螺栓与埋板连接，校准后进行焊接。
2
Reference Stars: Star with known position and/or magnitude, that are used to find the plate constants and photometric calibration of an image.
参考星：已知位置和/或星等的恒星，用于确定图片的底片常数和光度校准。
3
Alternatively, calibration may be checked using a Polarization Reference Standard, which consists of a plate of quartz mounted in a holder perpendicular to the light path.