4. Results

4.1. BVRI monitoring

One can see from Table 3 (click here) that the blazar was brightening during 1994; on 1994 November 8 the luminosity reached a maximum I=13.178 mag and increased by 1.6 mag as compared with that on 1994 April 11. Afterward, the luminosity declined and until 1995 February dropped down to near the 1994 April level. This agrees with the results reported by Sillanp et al. (1996). The variability on a timescale of one day in I band was only 0.04 mag. In other bands the error is too large to determine if there is variability.

4.2. Fast photometry in the I band

One can see the following results from Table 5 (available electronically) and Figs. 1-6.

1. On 1994 April 11 (Fig. 1 (click here)) we observed a change of magnitude of in about 8 minutes. 2. On 1994 November 7 (Fig.2) the light curve apparently began to fall at .394d, reached a minimum at .401d, then rised up. If this is real, the blazar has decreased by approximately mag in ten minutes and brightened about mag in about 3 minutes. 3. On 1994 November 8 (Fig. 3 (click here)) the light curve began to fall at .387d, reached a minimum at .393d, then rised up. If the variations are real, the magnitude has increased by in an interval of about 13 minutes and decreased by in about 3 minutes. 4. On 1995 February 8 (Fig. 4 (click here)) there was a first decline of 0.1 mag during two hours, then a rise and a second decline of 0.06 mag during 40 minutes. 5. On 1995 February 22 (Fig. 5 (click here)), the brightness of the blazar was going down slowly. 6. On 1995 February 23 (Fig. 6 (click here)) no rapid variations appeared.

 

Date 4/11/94 11/7/94 11/8/94 2/8/95 2/22/95 2/23/95

3.4099 11.4284 6.5732 9.7096 3.5122 0.9919

0.9232 1.2398 1.0428 1.2565 0.8501 0.8553

7 13 17 29 29 37

 

Table 4 (click here) lists the average of relative errors on the fluxes of the blazar, of star 4 and 10 (Row [2], [3] and [4]) and of R₁ and R₂ (Row [5] and [6]), the rms values of R₁ and R₂ relative to its average (Row [7] and [8]) and the reduced and of R₁ and R₂ (Row [9] and [10]). From this data, one sees that the variations of OJ 287 are real with a confidence level of 0.9985 (11 April 1994) or larger, except on 23 February 1995 for which no significant variations were observed. Star 5 is too faint to be used as a comparison star for such small variations.

  
Figure 1: Light curves of differential magnitude in the I band on 11th April 1994. Dm1 (left) is the differential magnitude between OJ 287 and comparison star 4. Dm2 (right) is the same between comparison stars 10 and 4

  
Figure 2: Light curves of differential magnitude in the I band on 7th November 1994. Dm1 (left) is the differential magnitude between OJ 287 and comparison star 4. Dm2 (right) is the same between comparison stars 10 and 4

  
Figure 3: Light curves of differential magnitude in the I band on 8th November 1994. Dm1 (left) is the differential magnitude between OJ 287 and comparison star 4. Dm2 (right) is the same between comparison stars 10 and 4

  
Figure 4: Light curves of differential magnitude in the I band on 8th February 1995. Dm1 (left) is the differential magnitude between OJ 287 and comparison star 4. Dm2 (right) is the same between comparison stars 10 and 4

  
Figure 5: Light curves of differential magnitude in the I band on 22th February 1995. Dm1 (left) is the differential magnitude between OJ 287 and comparison star 4. Dm2 (right) is the same between comparison stars 10 and 4

  
Figure 6: Light curves of differential magnitude in the I band on 23th February 1995. Dm1 (left) is the differential magnitude between OJ 287 and comparison star 4. Dm2 (right) is the same between comparison stars 10 and 4