SIMBAD references

We present a total of 12,436 photometric measures of 371 field stars of 26 quasars in the visible (UBVRI) and 22,276 photometric measures of 122 field stars of 13 quasars in the near-infrared (JHK), giving a total of 34,712 measures. Of these, 115 stars in 12 fields are calibrated in both ranges. One further field, Mrk 421, was calibrated, but on close examination all sources were found to be probably nonstellar; thus these results are not included here. The stars observed cover the range from V=11 to V=20 and from K=9 to K=17 and are well distributed around the sky north of declination -30°. This represents the initial sample of an extensive catalog of calibrated fields that will cover the northern sky down to declination -30° and that will cover a wide range of Galactic latitudes. These fields will be useful both for photometry of AGNs in the range from B to K and also as faint calibration standards for large telescopes. The median absolute total error on the photometry, including all known error sources, ranges from 0.008 mag in J to 0.034 mag in B. These errors will be greatly reduced with the addition of further data in the future, although the final precision is fundamentally limited by the photometric errors in the existing lists of calibration stars used to calibrate these data.