2. Data acquisition and calibration
The observations were performed with the multi-channel multi-colour photometer (MCCP) attached to the 0.8 m telescope at Mt. Wendelstein in the Bavarian Alps. This instrument measures the object, a nearby comparison star, and the sky background simultaneously in 5 colours (UBVRI) with high time resolution. The simultaneous measurements allow a nearly complete compensation for changing atmospheric extinction effects and varying background contributions. High precision differential photometric measurements of IP Peg relative to a nearby comparison star were obtained on 4 nights during the decline from an outburst. Data reduction followed the so-called "standard reduction procedure" (Barwig et al. 1987). A journal of the IP Peg observations is given in Table 1. In all nights an integration time of 2 seconds has been used. Fig. 1 shows the UBVRI light curves.
Table 1. Journal of observations. (IT: integration time, -flux: V magnitude at phase 0.25)
© European Southern Observatory (ESO) 1997
Online publication: April 6, 1998