As in Fig. 8 but compared against the BRASS benchmark spectrum of 51 Peg (G2.5IV), observed using the Mercator-HERMES spectrograph (black). Panel a: multiple literature log (gf) values that all provide a good fit to the observed line profile. Panel b: only one literature log (gf) value out of four fits the observed line profile well. Panels c and d: a number of Fe I line log (gf) values with varying qualities of fitting to the observed profiles ranging from excellent fit to poor fit. [1] Kostyk (1982), [2] Fuhr et al. (1988), [3] Lobel (2008), [5] May et al. (1974), [7] Landi et al. (2013), [8] Garz (1973), [9] Nahar (1993), [10] Wiese et al. (1969), [12] Martin et al. (1988), [13] Kostyk (1981), [14] Wallace & Hinkle (2009), [15] Blackwell et al. (1986), [16] Lawler et al. (2013), [4,6,11,17] Kurucz (1999–2014), [18] Raassen & Uylings (1998), [19] same reference as [18] but reported by NIST to a limited precision. The log (gf) uncertainty is ≥50% and calculated by NIST in the same manner as Kramida (2013), and [20] Blackwell et al. (1980).