Abstract:
The CCD magnitudes in Johnson BV and Cousins RI photometric passbands are determined for 18 stars in the field of GRB 990123. These mesurements can be used in carrying out precise CCD photometry of the optical transient of GRB 990123 using differential photometric techniques during non-photometric sky conditions. A comparison with previous photometry indicates that the present photometry is more precise.
