New flux data are presented for 60 FGK stars on and near the main sequence. All the measurements are made at wavelengths suitable for temperature determinations. Measurements of all but seven program stars include four passbands in the Brackett continuum as well as 12 passbands in the Paschen continuum. After the accuracy of the new data is shown to be satisfactory, measurements of three "solar proxies" are compared to theoretical flux data from a solar model atmosphere calculated by Kurucz. In this case, agreement with rms scatter at the 5-7 mmag level is obtained. In addition, a possible zero-point problem with synthetic photometry of two Kurucz solar atmospheres is detected. Using measurements for 48 of the program stars and the Kurucz model grid, two sets of temperature data are then derived. The first set is based solely on data for the Paschen continuum, and the second set is derived from data for both the Paschen and Brackett continua. When the resulting temperatures are compared to temperature data on an angular-diameter scale, some data in the first data set yield offsets of about 40 K. However, no such offsets are found for the second data set. It is concluded that the Kurucz models yield correct continua between 6056 and 10404 angstrom for the program stars. In contrast, it appears that some of those models do not quite reproduce the line blocking in that wavelength range. The latter deduction is supported by analyzing flux data for a star (61 Cyg A) with relatively large amounts of line blocking. It is recommended that the measurements reported here be used again when further tests of theoretical flux curves for FGK stars are performed.

In this paper, new Cousins VRI data are presented for NGC 752 and Praesepe, and new and extant data are combined into an augmented database for M67. For those three clusters, catalogs containing Cousins VRI photometry, reddening-corrected values of (V -K)(J), and temperatures are produced. The same is done for Coma by using both previously published and newly derived Cousins photometry. An extant set of catalogs for the Hyades is updated to include V magnitudes and values of (R -I)(C) that were published after the original catalogs appeared. Finally, M67 V magnitudes published previously by Sandquist are corrected for an effect that depends on location on the face of the cluster. The corrected data and values of (V -I)(C) given by Sandquist are then set out in a supplementary catalog. Data files containing all of these catalogs are deposited in the CDS archives. To assess the quality of the data in the catalogs, the consistency of extant Cousins VRI databases is tested by performing analyses with the following features: (1) quantities as small as a few millimags are regarded as meaningful; (2) statistical analysis is applied; (3) no use is made of data other than VRI measurements and comparable results; (4) no inferences are drawn from color-magnitude comparisons; (5) pertinent data that have not been included previously are analyzed; and (6) results based on direct comparisons of stellar groups at the telescope are featured. In this way, it is found that our updated M67 color data and those of Sandquist are on the E region zero point. In contrast, values of (V -I)(C) from Montgomery and collaborators are found to be too red by 27 +/- 3 mmag, with an even larger offset being likely for unpublished data from Richer and his collaborators. Zero-point tests of our Cousins VRI colors for Coma, Praesepe, and NGC 752 are also satisfactory. Scale factor tests of the M67 colors are performed, and a likely scale factor error in the Montgomery et al. colors is found. However, it appears at present that the scale factors of our M67 colors and those of Sandquist are satisfactory. For the most part, zero-point tests of the assembled V magnitudes are also satisfactory, although it is found that further work on the V magnitudes for Praesepe and M67 would be useful. To put these results in perspective, it is pointed out that photometric tests that are satisfactory at the few-millimag level have been published for some two decades and so are not appearing for the first time in this paper.

New Stromgren-beta Pleiades data on a zero point defined by the Hyades and Coma are presented. The new data and counterparts from four extant sources are compared to measurements published by Crawford & Perry in 1976. The only statistically significant problem found in this way is a 4 mmag offset obtained b - y from a data set published by McNamara in 1976. Results of similar comparisons published previously for Praesepe are updated by including three additional sets of published data. In this case, comparisons are made to measurements published by Crawford & Barnes in 1969. Two of the data sets (including one published by Joner & Taylor in 1995) yield accordant, statistically significant formal corrections to the b - y m(1) measurements of Crawford & Barnes. In addition, results from a third data set are consistent with those derived from the data of Joner & Taylor. However, this pattern is either partly or entirely absent from the offsets yielded by the other three data sets. Because the measurements of Joner & Taylor are still the only ones known to have been derived from direct comparisons among the Hyades, Coma, and Praesepe, it is concluded that the balance of evidence presently favors the offsets obtained from those data. In addition, it is noted that the data of Joner & Taylor do not imply that the data of Crawford & Barnes require corrections that depend on color. With these interim conclusions drawn, it is then suggested that further Praesepe measurements should be brought to bear on the problem.

A protocol for reddening analysis developed in previous papers in this series is reviewed here and applied to NGC 752. The protocol includes ( 1) detailed scrutiny of the histories of reddening determinations for program clusters, ( 2) adherence to statistical norms, ( 3) quality control of all reddening techniques, ( 4) a primary focus on techniques with limited metallicity sensitivity, ( 5) zero-point control of source data, ( 6) use of the solar neighborhood to establish a zero point for reddening values, ( 7) use of a standard permitting meaningful quantities to be as small as a few milli-magnitudes, and ( 8) rejection of ad hoc data assessments. After certain published results are set aside, it is found that a reddening value derived for F stars by using a technique that is insensitive to blanketing disagrees by about 0.04 mag with a value derived for K giants by using DDO photometry. This disagreement does not appear to be an artifact of the use of questionable data, and it persists if additional techniques are considered. Partly because two comparable reddening results for K giants are afterward found to disagree with each other, the problem is attributed to a blanketing effect ( with an unknown source) on the reddening values derived for the K giants. Pending a final resolution of that problem, the adopted value of E(B - V) for the cluster ( 44 +/- 3.4 mmag) is based solely on the initial F-star analysis. A discussion of the potential usefulness of small standard errors like the one derived here for E( B - V) is given. In a parallel investigation, it is found that no definitive value of [Fe/H] can be assigned to NGC 752 at present because a statistically significant disagreement between two published high-precision metallicities is detected.

From 1980 through 1998, the Wampler scanner and the 0.9 m Crossley reflector at Lick Observatory were used to obtain 137 nights of flux-curve measurements. In this paper, the resulting data are used to test, revise, and extend a set of flux curves for bright standard stars published in 1984. Full use is made of extensive measurements of a Lyr, the primary standard star. It is found that measurements made during spring and fall runs are highly consistent and that small systematic wavelength trends appearing in the standard-star data can be readily detected and corrected. This conclusion applies for 109 Vir in particular, and it is concluded that there is no convincing case for variation of this key standard star after 1979. Tests of the corrected and augmented flux curves using 13 color photometry yield a number of cases in which residuals are systematic with wavelength. However, for stars with E(B - V) < 0.12 mag ( including alpha Lyr), the revised and extended flux-curve data yield synthetic values of Stromgren u - b and b - y that are highly consistent with results from filter photometry. For almost all stars measured ( again including a Lyr), consistency with filter values of is ( V - R)(C) also obtained. Comparisons of the revised and augmented data with flux curves measured in the Soviet Union yield results ranging from fair agreement to marked disagreement. However, it is found that published data from additional sources include results that agree well with those presented here. Given this agreement, the results of the tests using filter photometry, and the character of the transformation coefficients for alpha Lyr, it is concluded that there is adequate support for the accuracy of the corrected standard-star flux curves. Recommendations about future measurements that can be used to test this conclusion are presented.

Since 1954, 70 reddening determinations have been published for M67. Those results are of very diverse quality, and they imply only that the value of E(B - V) for the cluster lies between -0.02 and +0.14 mag. In addition, this uncertainty is habitually concealed by long-standing citation practices. In response, a reformed reddening protocol called "alternative scholarship" is applied, with tenets including (1) rigorous published foundations for reddening values, (2) accountability for all extant reddening results for M67, (3) explicit quality control of reddening techniques, (4) use of techniques with limited metallicity sensitivity, (5) explicit zero-point control of input data (when possible), (6) a reddening zero point based ultimately on the dust-free solar neighborhood, and (7) adherence to statistical norms. Results from reddening maps are then set aside pending further examination of their zero points and accidental errors. In addition, reddening values derived from color-magnitude analysis and from averages of published reddening results are likewise set aside. Five techniques that satisfy the adopted protocol are then selected and applied. By averaging results from cluster A and F stars and K giants, one finds that the mean value of E(B - V) for M67 is 41 +/- 4 mmag. It is also found that extant results from additional techniques are consistent with this result or else can be set aside for plausible reasons. The analysis yields a collateral value of [Fe/H], and this is consistent with the derived reddening value. Using published high-dispersion data, it is found that the mean cluster value of [Fe/H] is -0:009 +/- 0: 009 dex. For M67 and the Hyades combined, no mean metallicity difference between giants and stars near the main sequence is found that is >= 0.036 dex at 95% confidence.