斯隆数字巡天(SDSS)在其网页上将自己标榜为“曾经进行过的最具雄心的天文观测”,这样说并不夸张。由于采用了很可能是曾经建造过的最大的数字摄像机(至少对于民用而言),SDSS的2．5m望远镜可在单次观察中测量600个星系和类星体的光谱。在2005年6月完成的第一阶段运行中,该巡天观测项目记录了近2亿个天体的影像,测量了67．5万多个星系和9万多个类星体的光谱,并由此确定了它们的距离。 It is not an exaggeration to say that the SDSS, on its web page, advertises itself as “the most ambitious astronomical observation ever done.” The SDSS 2.5m telescope measures the spectrum of 600 galaxies and quasars in a single observation due to the use of the largest digital camera likely to have ever been built (at least for civilian use). During the first phase of operation, completed in June 2005, the Sky Survey project recorded images of nearly 200 million celestial bodies, measured the spectra of more than 675,000 galaxies and more than 90,000 quasars, and determined The distance between them.