4. Optical objects near the BL LAC and the bright quasar
Fig. 2 shows a region around the BL Lac pictured in the X-ray map of Fig. 1. The optical image in Fig. 2 is from the digitized 103a-E Palomar Sky Survey plate. There is a BSO N and another BSO S. They are likely to be quasars and it would be important to find out what their redshifts are - presumably higher than the BL Lac.
Fig. 3 shows a region around the strong X-ray quasar. The BSO immediately NW, #2, appears, on the 103a-O Sky Survey, to be connected to the quasar by a thin, faint filament. This should be checked with deeper images and the spectrum of the BSO obtained. Objects #3 and #4 appear to be red and slightly extended but because of their exact alignment their spectra would also be interesting. Positions accurate to about and approximate apparent magnitudes and colors of these new candidates are given in Table 1.
Table 1. Objects near the BL Lac object and the quasar.
An X-ray source only from the quasar was identified as MSS 1217.0 +0700 (Stocke et al. 1991). Its position is shown by a plus sign in Fig. 1. It was identified as a Sey 1 of V = 16.3 mag. and z =.080. It was not registered by the ROSAT exposure and the identification should be further checked (see Arp 1997a).
© European Southern Observatory (ESO) 1997
Online publication: March 26, 1998