1 various Stauffer papers from 1980 through 1990
 1  (Stauffer 1980AJ.....85.1341S, Stauffer 1982AJ.....87.1507S,
 1  Stauffer 1984ApJ...280..202S, Stauffer & Hartmann 1987ApJ...318..337S,
 1  Stauffer et al. 1989ApJ...344L..21S);
 2 Landolt (1979ApJ...231..468L);
 3 Johnson & Mitchell (1958ApJ...128...31J) and/or
 3  Iriarte (1967BOTT....4...79I);
 4 van Leeuwen, Alphenaar, & Brand (1986A&AS...65..309V);
 5 Prosser et al. (1991AJ....101.1361P);
 6 Festin (1998A&A...333..497F);
 7 Stauffer et al. (1998ASPC..154.1331S);
 8 Rosvick et al (1992A&A...255..130R);
 9 Mermilliod et al. (1997, Cat. J/A+A/320/74);
10 Steele et al. (1995MNRAS.272..630S);
11 average of photometry from (1) and from Messina (2001A&A...371.1024M);
12 average of data from (1), (5) and (10)
13 average of (1) and (3) for the I_C_ magnitude
14 average of Messina (2001A&A...371.1024M), Landolt (1979ApJ...231..468L),
14  and van Leeuwen, Alphenaar, & Brand (1986A&AS...65..309V);
15 average of Johnson & Mitchell(1958ApJ...128...31J),
15  Stauffer (1984ApJ...280..202S), van Leeuwen, Alphenaar, & Brand
15  (1986A&AS...65..309V), and Messina (2001A&A...371.1024M);
16 average of (1) and Robinson & Kraft (1974AJ.....79..698R);
17 average of (1), Messina (2001A&A...371.1024M),
17  and Robinson & Kraft (1974AJ.....79..698R);
18 average of (1) and (2)
19 from Pinfield et al. (2000, Cat. J/MNRAS/313/347), but converted to
19  I_C_ estimate as detailed above;
20 photographic photometry from Stauffer et al. (1991AJ....101..980S);
21 photographic photometry from Hambly et al. (1993, Cat. J/A+AS/100/607);
22 estimate of I_C_ derived from Deacon & Hambly (2004, Cat. J/A+A/416/125)
22  as described above;
23 estimate of I_C_ derived from Slesnick et al. (2006, Cat. J/AJ/132/2665)
23  as described above.