3. Results

The dates of observations and the differential photometry results for each source are presented in Tables 1 (click here) and 2 (click here). The source name and redshift are given in Cols. 1 and 2. It should be noted that the right ascension (RA) and declination (DEC) of these sources are included with the finding charts (Fig. 1 (click here)). The dates when each source was observed and the number of observations in each night per filter are presented in Cols. 3 and 4 respectively. The differential magnitudes (, , ) between the reference stars and the radio-quiet quasar (Q) are given in Col. 5. In cases where there was more than one observation of a source in a night, the average value of the differential magnitudes are given in Col. 5. The photometric error () is given in Col. 6.

The major result is that no statistically significant rapid variability was observed for any of the sources listed Tables 1 (click here) and 2 (click here). The data also reveal no night to night or longer term variability for any of the sources, with the sole exception of PG 2112+059. This source brightened by 0.18 magnitudes in the V-band between September 1992 and June 1996 (Table 1 (click here) and Fig. 2 (click here)). The source with the largest number of observations is PG 0117+213 (Table 1 (click here)) and some of the differential V-band results are presented in Fig. 3 (click here). No significant short term variability was observed. Furthermore careful analysis of the remainder of the V-band data and all of the B-band revealed no significant short or long term variability.

  
Figure 2: Differential V band photometry between the radio quiet quasar PG 2112+059 (QSO) and three reference stars R1, R2 and R3 and differential photometry between the reference stars R1-R2 and R1-R3. The star R3 was unobservable during September 1990, due to the small CCD field of view. The average relative magnitude per night is plotted

  
Figure 3: Differential V band photometry between the radio quiet quasar PG 0117+213 (QSO) and the two reference stars R1 and R2 and differential photometry between the reference stars R1-R2. The origins of the time axes of the two upper plots are 00:50 UT on September 15 and 00:32 UT on September 19, 1990. The origins of the time axes of the lower plots are 22:12 UT on October 31 and 22:43 UT on November 1, 1991

The sources in this sample can be divided into three main redshift groups; A(z<2), B(2<z<3), C(z>3), and the following section includes comments on a number of the sources in these three categories.

A(z<2)

PG 0117+213 was the most frequently observed source in the sample and no significant variability was detected. The spectra of the source reveal the emission lines C III and C IV at (Hewitt & Burbidge 1987). Infrared observations over a period of years show maximum variability of 0.05 and 0.16 magnitudes at 2.2 m and 10.1 m respectively (Neugebauer et al. 1989). Sagar et al. (1996) observed this RQQSO during November 1996 and detected a hint of optical microvariability and suggested that careful monitoring of this source should continue. The only source in this sample of RQQSOs to display variability is PG 2112+059. It was observed during 1990, 1992 and 1996 and was found to have brightened by 0.18 magnitudes between September 1992 and June 1996 (Table 1 (click here)). PG 2302+029 reveals emission peaks in its spectrum which have been identified with Fe III multiplets (Wampler 1986). This source has a redshift z=1.044 and m_B=16.03. No variability was detected during the 1991 or 1992 observing runs. US 1420, US 1443 and US 1498 are all ultraviolet excess sources. Spectroscopy of blue and ultraviolet excess sources was reported Mitchell et al. (1984) and the redshifts are given in Table 2 (click here). These sources and the remaining sources in this category displayed no rapid variability.

B(2<z<3)

H 1011+091 is a broad absorption line
(BAL) RQQSO with m_V=17.8 (Hartig & Baldwin 1986). The Mg II emission line yields z=2.27 (Drew & Boksenberg 1984). The source 1146+111D has a redshift z=2.12 and is part of a compact group of five quasars with similar apparent magnitude and redshift and all within a diameter of 4 arcminutes (Hazard et al. 1979). The sources 1201-015 and 1222+023 were detected optically and listed by MacAlpine & Williams (1981). 1201-015 has an estimated m_V=18.0, and emission lines 3970 and 4560 believed to be Ly and O Iv yielding z=2.26; 1222+023 has z=2.05 and an estimated m_V=17.0. PG 1247+268 was observed by Green et al. (1980). The optical spectrum shows four strong emission features Ly + N V, Si IV+ O IV, C IV and C III with z=2.041 and m_V=15.8.

C(z>3)

1159+123 discovered by Hazard et al. (1984) using objective prism plates from the UK Schmidt telescope is a strong emission-line RQQSO with and m_V=17.5. Irwin et al. (1991) carried out a very successful multicolour survey in B, R and I (selected B-R) to search for high redshift quasars. Using this method they found 27 quasars at z>4. R-band data for nine of these high redshift quasars are given in Table 2 (click here): BR 0945-0411, m_R=18.80; BRI 1013+0035, m_R=18.80; BR 1033-0327, m_R=18.50; BRI 1050-0000, m_R=18.59; BRI 1108-0747, m_R=18.13; BRI 1110+0106, m_R=18.30; BR 1144-0723, m_R=18.60; BR 1202-0725, m_R=18.70 and BRI 1500+0824, m_R=19.25. No variability was found, however the search for optical variability in these high redshift RQQSOs will continue.

 

number of differential magnitude

object Name z dates of obs. error

obs. per filter R1-Q R2-Q R3-Q R1-Q R2-Q R3-Q

PG 0117+213 1.493 15-09-90 13B 16V -0.59 -0.13 -- -1.23 -0.52 -- 0.05

19-09-90 14B 15V -0.59 -0.12 -- -1.22 -0.51 -- 0.05

31-10-91 4B 5V -0.56 -0.11 -- -1.23 -0.53 -- 0.02

01-11-91 5B 6V -0.57 -0.13 -- -1.23 -0.53 -- 0.02

21-09-92 1B 1V -0.57 -- 3.10 -1.19 -- 2.28 0.04

22-09-92 1B 1V -0.58 -- 3.21 -1.18 -- -- 0.04

23-09-92 1B 1V -0.54 -- 3.21 -1.20 -- -- 0.04

24-09-92 1B 1V -0.56 -- 3.17 -1.24 -- 2.30 0.04

25-09-92 -- 1V -- -- -- -1.23 -- 2.39 0.04

26-09-92 1B 1V -0.55 -- -- -1.21 -- 2.33 0.04

27-09-92 1B 1V -0.57 -- 3.35 -1.24 -- 2.32 0.04

PG 2112+059 0.466 15-09-90 -- 8V -- -- -- 0.35 0.66 -- 0.03

16-09-90 6B 6V 0.76 1.34 -- 0.35 0.65 -- 0.03

21-09-92 2B 2V 0.72 1.34 0.82 0.31 0.61 0.23 0.03

22-09-92 1B 1V 0.71 1.33 0.82 0.33 0.62 0.21 0.03

25-09-92 2B 2V 0.73 1.34 0.84 0.32 0.60 0.22 0.03

26-09-92 1B 1V 0.72 1.32 0.82 0.33 0.60 0.23 0.03

28-05-96 -- 2V -- -- -- 0.51 0.81 0.41 0.03

31-05-96 -- 3V -- -- -- 0.50 0.80 0.39 0.03

01-06-96 -- 2V -- -- -- 0.49 0.79 0.40 0.03

03-06-96 -- 4V -- -- -- 0.50 0.77 0.42 0.03

PG 2302+029 1.044 26-10-91 1B 1V 0.22 0.59 -- -0.44 0.19 -- 0.03

31-11-91 2B 2V 0.26 0.54 -- -0.40 0.24 -- 0.03

01-11-91 1B 1V 0.25 0.56 -- -- 0.22 -- 0.03

02-11-91 1B 1V 0.25 0.60 -- -0.40 0.24 -- 0.03

20-08-92 1B 1V 0.27 0.54 -- -0.38 0.24 -- 0.03

 

 

object Name z dates of observations differential magnitude error

observations per filter R1-Q R2-Q R3-Q

US 1420 1.473 18-02-93 2V -0.90 -1.78 0.30 0.04

20-02-93 1V -0.94 -1.80 0.28 0.04

21-02-93 2V -0.94 -1.82 0.34 0.04

23-02-93 1V -0.93 -1.82 0.32 0.04

US 1443 1.564 18-02-93 2V -0.97 -0.74 -0.52 0.03

21-02-93 2V -0.95 -0.75 -0.50 0.03

23-02-93 2V -0.98 -0.72 -0.52 0.03

US 1498 1.406 18-02-93 2V 0.10 -0.44 0.37 0.03

21-02-93 2V 0.10 -0.44 0.35 0.03

23-02-93 2V 0.09 -0.45 0.34 0.03

BR 0945-04 4.118 22-02-93 2R -3.59 -2.02 -- 0.07

24-02-93 2R -3.52 -1.95 -- 0.03

19-12-95 3R -3.54 -1.97 -- 0.03

H 1011+091 2.27 18-02-93 2R -- -1.15 -1.61 0.03

21-02-93 2R 0.12 1.12 -1.58 0.03

23-02-93 2R 0.11 -1.10 -1.60 0.03

BRI 1013+00 4.38 22-02-93 2R -2.76 -2.89 -- 0.03

24-02-93 2R -2.78 -2.89 -- 0.03

BR 1033-03 4.50 22-02-93 2R -1.13 -2.59 -- 0.03

BRI 1050-00 4.29 22-02-93 2R -0.37 0.20 -- 0.04

19-12-95 2R -0.32 0.22 -- 0.04

BRI 1108-07 3.94 22-02-93 2R -0.38 -1.83 -- 0.04

BRI 1110+01 3.93 22-02-93 2R -1.67 -1.87 -- 0.04

BR 1144-08 4.16 22-02-93 2R -2.60 -1.83 -- 0.04

1146+111D 2.12 18-02-93 2R -0.20 0.15 -2.03 0.03

20-02-93 2R -0.20 0.13 -2.04 0.03

21-02-93 2R -0.18 0.17 -2.00 0.03

23-02-93 2R -0.19 0.18 -1.99 0.03

1159+123 3.51 18-02-93 2R 0.23 -0.29 0.44 0.04

20-02-93 2R 0.21 -0.28 0.47 0.04

21-02-93 2R 0.20 -0.29 0.44 0.04

1201-015 2.26 19-02-93 2R -3.39 -2.38 -- 0.04

21-02-93 1R -3.44 -2.34 -0.68 0.04

23-02-93 2R -3.45 -2.33 -0.67 0.04

BR 1202-07 4.70 22-02-93 2R -0.03 -0.61 -- 0.07

1222+023 2.05 19-02-93 2R -3.00 0.92 -1.81 0.05

21-02-93 2R -3.02 0.92 -1.81 0.05

23-02-93 2R -2.98 0.93 -1.76 0.05

PG 1247+268 2.041 18-02-93 1R 1.37 2.03 1.73 0.03

21-02-93 2R 1.35 2.06 1.77 0.03

W 61972 1.92 18-02-93 2R 0.51 -1.20 -1.83 0.02

21-02-93 2R 0.51 -1.20 -1.82 0.02

23-02-93 1R -- -1.20 -1.85 0.02

PG 1329+412 1.93 18-02-93 2R -0.67 0.79 -1.55 0.03

23-02-93 2R -0.67 0.77 -1.54 0.03

BRI 1500+08 3.96 23-02-93 2R -0.82 -0.92 -- 0.07

17-03-94 2R -0.86 -- -- 0.07