Fig. 2
Cumulative number of quasars as a function of observation date during all the iterations of SDSS (York et al. 2000; Eisenstein et al. 2011; Blanton et al. 2017). Vertical lines show the equivalence between modified Julian dates and usual calendar dates. A total of 526 356 quasars have been spectroscopically confirmed. The “flat portions” in this figure correspond to annual summer shutdown for the telescope maintenance.
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