The data reduction was performed by using the IRAF program package. The CCD reductions included bias subtraction, flatfield correction and cosmic-ray removal. Spectra of a He-Ne-Ar or Fe-Ar lamp were taken to get an absolute wavelength scale. The flux calibration was derived with 2 to 3 observations of KPNO IIDS standard Stars (Strom 1979) per night. The atmospheric extinction was corrected by using the mean extinction coefficients of Xinglong Station, which were measured by BATC multi-color survey (Yan 1995).
The X-ray characteristics and optical properties of the 9 BLRQs are summarized in Tables 2 and 3, and their spectra are shown in Fig. 1. Position error radius, count rates, hardness ratios 1 & 2 listed in Table 2 are from RASS-BSC. Hardness ratios are defined as:
where H, S, H1, and H2 are the count rates in the hard H-band (0.4-2.4 keV), the soft S-band (0.07-0.4 keV), the hard H1-band (0.4-1.0 keV) and the hard H2-band (1.0-2.4 keV) respectively. The coordinates given in Table 3 were obtained from USNO-A1.0. We applied these coordinates to the Digitized Sky Survey and did not find any ambiguous identifications of the objects, so we do not give the finding charts of the 9 BLRQs. The average redshifts were usually determined from two or more emission lines. The B and R magnitudes were obtained from USNO-A1.0 and have an accuracy between 0.25 and 0.40 magnitudes depending on the declination (Monet et al. 1996). The absolute B magnitudes were calculated by the same formula used by Véron-Cetty & Véron (1996) under the assumption of H0=50kms-1Mpc-1 and q0=0. The listed in Table 3 is the angular separation between the X-ray centroïd and the optical countpart in arcseconds.
Special thanks to Dr. Qiu Yulei and Dr. Jiang Biwei for their hard work of English revision of this paper. We are grateful to Miss Cao Li for her kindly help with data reduction. We also thank Mr. Yan Haojing for providing the extinction data of Xinglong Station. This work is partly supported by the Pandeng Project of the Chinese Scientific Committee and the Chinese National Natural Science Foundation.
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