SIMBAD references

Photometry in R and I' (similar to I) for the gravitional lens system Q 2237+0305 are presented in order to monitor the light curves of the four quasar components over a period of hours to days; i.e., the time delay over which instrinic brightness variations would be observed according to theoretical models.

No variations were found of any kind during a three day period, but comparison of the R data with previously published observations provides new information on the microlensing of component B reported in 1992. This component appears to have increased in brightness by at least 0.5 mag between March and July 1991, and has decreased in brightness from the maximum by at least 0.15 mag by mid-June 1992.

Light curves representing the history of the four components are discussed in detail from which the rise time for component B, < 720 days, and the event duration, >4 yr, are estimated.