DDO photometry of E-region stars and equatorial standards .2.

This paper deals with the observations of 72 of McClure's equatorial standard stars, made with the same photometer and DDO filters as were used for the E-region stars in Cousins' Paper I in order to standardize the observations. These observations were reduced in the natural system and later transformed into McClure's system. Zero-point ties between the equatorial and E-region stars were also needed to standardize the latter system. With the exception of C (38 - 41), our photometry agrees as well with McClure's standard system as his own observations do, but both show some small, apparently systematic, differences which are almost inevitable with a system like the DDO unless the response functions are very well matched. Comparisons with 17 of Dean's measurements of E-region stars show good agreement (similar to 2 mmag) for the averaged zero-points, but there are small colour differences affecting C (35 - 38) and C (38 - 41) because of differences between the filters and the reduction procedures. This paper also deals with several problems in the DDO photometry that have implications for precision photometry in general.