RX J1716.2+6836 Also called RX J1716.0+6836 in Boller et al. 
RX J1716.2+6836  (1997MNRAS.289..393B). The identification comes from the 
RX J1716.2+6836  revised Burbidge catalog (Hewitt & Burbidge, Cat. VII/158,
RX J1716.2+6836  1993ApJS...87..451H). 
RX J1717.7+6431 There is a star within the error circle that is closer to the 
RX J1717.7+6431  X-ray position (7.7") than the AGN2. We still believe that the 
RX J1717.7+6431  AGN2 is the correct identification, not only because it is an 
RX J1717.7+6431  AGN but also because it appears to be in a distorted spiral in 
RX J1717.7+6431  our UH 2.2m B-band image. Distortion implies some kind of 
RX J1717.7+6431  interaction and often these distorted galaxies are X-ray 
RX J1717.7+6431  sources. 
RX J1719.8+6457 This source is one of two sources in the NEP still unidentified.
RX J1719.8+6457  Optical spectra were taken for seven objects within 80" from
RX J1719.8+6457  the X-ray position, but no plausible identification was found.
RX J1720.8+6210 There are two galaxies at the same redshift as the AGN1 
RX J1720.8+6210  (z=0.7313) and closer to the X-ray centroid (approximate 
RX J1720.8+6210  positions from DSS-2 red are for cfh 11, 
RX J1720.8+6210  RA_2000_ = 17 20 46.8, DE_2000_ = +62 10 25; and for cfh 12b,
RX J1720.8+6210  RA_2000_ = 17 20 43.9, DE_2000_ = +62 10 11). We still identify
RX J1720.8+6210  the source as AGN1 since its spectrum shows a broad Mg II 
RX J1720.8+6210  emission line (FWHM>4000km/s). However, the presence of a 
RX J1720.8+6210  distant cluster at z~0.73 is not excluded. 
RX J1723.1+6826 This source is identified with a QSO (RA_2000_ = 17 23 09.9, 
RX J1723.1+6826  DE_2000_ = +68 26 56;, z=0.9782+/-0.001) that is 4" away from 
RX J1723.1+6826  the X-ray centroid. The optical spcetrum shows a very broad 
RX J1723.1+6826  Mg II emission line (FWHM>=7000km/s). A second object at 
RX J1723.1+6826  RA_2000_ = 17 23 10.1, DE_2000_ = +68 26 51, just south of the 
RX J1723.1+6826  QSO and only 3.4" away from the X-ray centroid, has a similar 
RX J1723.1+6826  redshift (z=0.9777) as the QSO. This second object is fainter 
RX J1723.1+6826  and has a narrower Mg II line in emission. Both objects could 
RX J1723.1+6826  contribute to the X-ray emission even if we indicate the object
RX J1723.1+6826  with broader Mg II line as the identification in the table. 
RX J1724.1+7000 and RX J1724.2+6956 These two sources were identified as a group
RX J1724.1+7000  of galaxies in Henry et al. (1995ApJ...449..422H). The X-ray 
RX J1724.1+7000  morphology is complex and elongated along the north-south 
RX J1724.1+7000  direction (see Fig. 1a in Henry et al.. 1995ApJ...449..422H). 
RX J1724.1+7000  We confirm here the identification of these sources with a 
RX J1724.1+7000  single group of galaxies at z=0.0386. 
RX J1724.2+6956 See RX J1724.1+7000.
RX J1727.0+6926 A radio source (0.96+/-0.06mJy at 6cm) was detected with the VLA
RX J1727.0+6926  in the DnC array at the position of the optical counterpart by 
RX J1727.0+6926  T. Rector (2003, private communication). 
RX J1727.8+6748 There are several galaxies in the area for which no optical 
RX J1727.8+6748  spectrum is available. The suggested identification is the AGN1
RX J1727.8+6748  at z=0.4950 (RA_2000_ = 17 27 45.5, DE_2000_ = +67 48 43) lying
RX J1727.8+6748  22" away from the X-ray centroid, with a broad (FWHM>7000km/s) 
RX J1727.8+6748  Mg II emission line in its optical spectrum. 
RX J1732.5+7031 This object appears in the sample of identified northern ROSAT 
RX J1732.5+7031  sources by Appenzeller et al. (1998ApJS..117..319A) with a 
RX J1732.5+7031  redshift z=0.209 versus our z=0.2114. 
RX J1732.9+6533 The redshift for this QSO (z=0.8560) comes from Hewitt & 
RX J1732.9+6533  Burbidge (Cat. VII/158, 1993ApJS...87..451H). 
RX J1736.3+6802 This group of galaxies was published in Henry et al. 
RX J1736.3+6802  (1995ApJ...449..422H). There are 12 galaxies with spectroscopic
RX J1736.3+6802  redshifts. Refer to Henry et al. (1995ApJ...449..422H) for more
RX J1736.3+6802  details and for an X-ray contour image (their Fig. 1c). 
RX J1736.9+6845 This X-ray source is MS 1737.2+6847 and its identification with 
RX J1736.9+6845  SAO17576 ({omega} Draconis) comes from the EMSS; see Stocke et 
RX J1736.9+6845  al. (1991ApJS...76..813S) and Maccacaro et al. 
RX J1736.9+6845  (1994ApL....29..267M). 
RX J1736.4+6820 The X-ray source is identified with GAT 732, a star with an E 
RX J1736.4+6820  magnitude in APM of 8.98. The star has a high proper motion 
RX J1736.4+6820  (about 1' in 50yr). 
RX J1739.7+6710 This source is MS 1739.8+6712 and is identified as AGN1. The 
RX J1739.7+6710  redshift, z=0.118, comes from Stocke et al. 
RX J1739.7+6710  (1991ApJS...76..813S); an optical finding chart is published in
RX J1739.7+6710  Maccacaro et al. (1994ApL....29..267M). 
RX J1741.2+6507 There is a cluster candidate in the field of this source 
RX J1741.2+6507  identified as AGN1 at z=0.7466. We have concordant redshifts 
RX J1741.2+6507  for two galaxies (A and B): 
RX J1741.2+6507  RA_2000_ = 17 41 15.5, DE_2000_ = +65 07 53, z_A_=0.3797; 
RX J1741.2+6507  RA_2000_ = 17 41 07.7, DE_2000_ = +65 07 47, z_B_=0.3775. 
RX J1743.4+6341 This cluster, associated with A2280, has a large gravitational 
RX J1743.4+6341  arc that is described in Gioia et al. (1995A&A...297L..75G). 
RX J1745.2+6556 In the field of this source, identified as a cluster of galaxies
RX J1745.2+6556  at z=0.6080+/-0.0005 (optical spectrum for a member galaxy is 
RX J1745.2+6556  shown in Fig. 10) there is also an AGN (RA_2000_ = 17 45 17.6, 
RX J1745.2+6556  DE_2000_ = +65 56 02, z=0.2904) that is ~18" away from the 
RX J1745.2+6556  X-ray centroid. The AGN could contribute to the X-ray emission 
RX J1745.2+6556  of the source. However, it is difficult to classify the AGN as 
RX J1745.2+6556  type 1 or type 2 since there is no H{beta} emission line, and 
RX J1745.2+6556  the H{alpha} emission line is blended with N II. The spectrum 
RX J1745.2+6556  of the AGN has a very red continuum. 
RX J1746.1+6737 The identification of this X-ray source comes from the EMSS. 
RX J1746.1+6737  This is MS 1746.2+6738 identified as AGN1 at z=0.041 by Stocke 
RX J1746.1+6737  et al. (1991ApJS...76..813S). The AGN1 (RA_2000_ = 17 46 08.8, 
RX J1746.1+6737  DE_2000_ = +67 37 15) is 25" south of a bright SAO star 
RX J1746.1+6737  (SAO17632, RA_2000_ = 17 46 08.7, DE_2000_ = +67 37 43, 
RX J1746.1+6737  m_V_=7.79), which could also contribute to the X-ray emission. 
RX J1746.2+6227 The redshift for this QSO (z=3.889) is taken from Hook et al. 
RX J1746.2+6227  (1995MNRAS.273L..63H; see their Fig. 2 for a spectrum). Stickel
RX J1746.2+6227  (1993A&A...275...49S) gives a redshift of z=3.886 for this 
RX J1746.2+6227  object. The QSO was independently discovered as an X-ray source
RX J1746.2+6227  by Becker, Helfand, & White (1992AJ....104..531B), who measured
RX J1746.2+6227  a redshift of z=3.87 (optical spectrum in their Fig. 2). An 
RX J1746.2+6227  X-ray spectrum with ASCA is published in Figure 1 of Kubo et 
RX J1746.2+6227  al. (1997MNRAS.287..328K). 
RX J1747.0+6836 This very bright source is MS 1747.2+6837. The identification as
RX J1747.0+6836  AGN1 (z=0.063) comes from Kriss & Canizares 
RX J1747.0+6836  (1982ApJ...261...51K) and Stocke et al. (1991ApJS...76..813S). 
RX J1747.0+6836  P. F. Winkler (1982, private communication) originally 
RX J1747.0+6836  discovered this object. 
RX J1747.4+6626 There are two objects here, both AGN1 and at the same redshift 
RX J1747.4+6626  (z=0.1391), which could both contribute to the X-ray emission. 
RX J1747.4+6626  The optical position for one of them is RA_2000_ = 17 27 47.0, 
RX J1747.4+6626  DE_2000_ = +66 26 24 (given in Table 3). The second object, 
RX J1747.4+6626  which is a spiral galaxy at z=0.1390, is at 
RX J1747.4+6626  RA_2000_ = 17 47 26.6, DE_2000_ = +66 26 05. 
RX J1747.9+6623 We identify this source as a normal galaxy (GAL), but there are 
RX J1747.9+6623  two objects possibly interacting. Object A 
RX J1747.9+6623  (RA_2000_ = 17 47 58.5, DE_2000_ = +66 23 26, z=0.1739) is a 
RX J1747.9+6623  narrow emission-line galaxy with H{alpha}, H{beta}, H{gamma}, 
RX J1747.9+6623  and [O III] emission lines in the optical spectrum and shows 
RX J1747.9+6623  the morphology of a disturbed spiral. Object B 
RX J1747.9+6623  (RA_2000_ = 17 47 56.8, DE_2000_ = +66 23 46, z=0.1737) does 
RX J1747.9+6623  not show any emission line in the spectrum and resembles an 
RX J1747.9+6623  edge-on spiral in our UH 2.2m open image. 
RX J1748.5+7005 Identification and redshift for this BL Lac comes from the 
RX J1748.5+7005  literature. An optical spectrum is published in Figure 7 of 
RX J1748.5+7005  Lawrence et al. (1996ApJS..107..541L); see also note in 
RX J1748.5+7005  Rector & Stocke (2001AJ....122..565R). 
RX J1748.6+6842 There are two AGNs with similar redshift (z=0.0537 and z=0.0540)
RX J1748.6+6842  that are blended in the APM finder. The western object 
RX J1748.6+6842  (RA_2000_ = 17 48 38.3, DE_2000_ = +68 42 17) has broad 
RX J1748.6+6842  emission lines in its optical spectrum. We indicate this object
RX J1748.6+6842  as the identification (AGN1). The eastern object 
RX J1748.6+6842  (RA_2000_ = 17 48 38.7, DE_2000_ = +68 42 16) has H{alpha} in 
RX J1748.6+6842  emission but it is difficult to assess the width of the 
RX J1748.6+6842  emission line since the spectrum is rather noisy. Both objects 
RX J1748.6+6842  look like spiral galaxies in our UH 2.2m open image. The two 
RX J1748.6+6842  objects might be interacting, and both could contribute to the 
RX J1748.6+6842  X-ray emission. 
RX J1751.2+6533 This source is associated with the group of galaxies published 
RX J1751.2+6533  in Figure 1e of Henry et al. (1995ApJ...449..422H). The 
RX J1751.2+6533  redshift has been updated using more accurate low-redshift data
RX J1751.2+6533  from Falco et al. (1999PASP..111..438F). 
RX J1751.5+7013 This source is identified with a cluster of galaxies at 
RX J1751.5+7013  z=0.4925. The two galaxies, for which we have optical spectra, 
RX J1751.5+7013  have narrow emission lines typical of AGN2. One of the AGN2 
RX J1751.5+7013  (RA_2000_ = 17 52 33.1, DE_2000_ = +70 13 01, z=0.4936) has a 
RX J1751.5+7013  narrow Mg II line in emission, in addition to H{beta} and to 
RX J1751.5+7013  [O II] and [O III] lines. 
RX J1752.2+6522 This source is identified as a cluster of galaxies at z=0.3923. 
RX J1752.2+6522  There is also an emission-line object 
RX J1752.2+6522  (RA_2000_ = 17 52 12.9, DE_2000_ = +65 22 36) that is 15.1" 
RX J1752.2+6522  away from the X-ray position with z=0.3940. We still identify 
RX J1752.2+6522  the source with a cluster of galaxies since the spectrum of the
RX J1752.2+6522  AGN, with H{beta} in emission, is too noisy to assess the width
RX J1752.2+6522  of the line. 
RX J1753.9+7016 This source is MS 1754.5+7017 and is identified as an AGN1 at 
RX J1753.9+7016  z=0.062 by Stocke et al. (1991ApJS...76..813S). 
RX J1754.0+6452 The redshift for this cluster is tentative because it is based 
RX J1754.0+6452  on three low S/N spectra. 
RX J1754.6+6803 This is MS 1754.9+6803. The redshift (z=0.0770) was measured by 
RX J1754.6+6803  Stocke et al. (1991ApJS...76..813S) and is based on three 
RX J1754.6+6803  galaxy spectra taken at the MMT in 1985 April. 
RX J1756.2+7042 This is one of the two still unidentified sources in the whole 
RX J1756.2+7042  NEP survey. The X-ray source is a double source elongated in 
RX J1756.2+7042  the east-west direction. The eastern X-ray centroid is 
RX J1756.2+7042  identified with an AGN1 (RA_2000_ = 17 56 14.9, 
RX J1756.2+7042  DE_2000_ = +70 41 56, z=0.838) since it shows a broad Mg II 
RX J1756.2+7042  line in emission in its optical spectrum. The western source is
RX J1756.2+7042  still unidentified. We have taken spectra for several objects 
RX J1756.2+7042  in the area using the Keck II, but none of the objects seems to
RX J1756.2+7042  be a satisfactory identification. 
RX J1757.2+7033 This source is MS 1757.7+7034, identified by Stocke et al. 
RX J1757.2+7033  (1991ApJS...76..813S) as a BL Lac at z=0.407, from Ca II H and 
RX J1757.2+7033  K, G band, and Mg I b absorption lines. 
RX J1757.2+6547 This X-ray source, identified with an M star 
RX J1757.2+6547  (RA_2000_ = 17 57 14.3, DE_2000_ = +65 46 58, m_E_=14.68), is 
RX J1757.2+6547  9.4" away from the X-ray centroid in the APM finders. There is 
RX J1757.2+6547  also an AGN1 (RA_2000_ = 17 57 13.6, DE_2000_ = +65 46 45, 
RX J1757.2+6547  z=0.578) 15.7" away from the X-ray centroid with m_E_=19.53 and
RX J1757.2+6547  m_O_=20.0. The AGN1 could also contribute to the X-ray emission
RX J1757.2+6547  of the source. 
RX J1757.3+6631 There are five spectroscopic redshifts for this cluster at 
RX J1757.3+6631  z=0.6909. The spectra were taken at the CFHT. None of the five 
RX J1757.3+6631  galaxies are visible on the APM, thus the optical positions are
RX J1757.3+6631  approximate coordinates measured from the DSS-2 red plate. Two 
RX J1757.3+6631  of the cluster galaxies (cfh 2 at RA_2000_ = 17 57 46.3, 
RX J1757.3+6631  DE_2000_ = +66 30 26, z=0.7006; and cfh 8 at 
RX J1757.3+6631  RA_2000_ = 17 57 29.9, DE_2000_ = +66 32 29, z=0.6860) are 
RX J1757.3+6631  identified as AGN2 galaxies since their optical spectra show 
RX J1757.3+6631  similar narrow forbidden [O III], [O II] and permitted H{beta} 
RX J1757.3+6631  and H{gamma} emission lines. 
RX J1757.9+6609 This source is identified with an AGN2 (RA_2000_ = 17 57 56.5, 
RX J1757.9+6609  DE_2000_ = +66 09 20, z=0.4865) only 4" away from the X-ray 
RX J1757.9+6609  position. See Figure 6 for an optical spectrum of the AGN2. 
RX J1757.9+6609  However, spectroscopic redshifts for two galaxies 
RX J1757.9+6609  (RA_2000_ = 17 58 02.1, DE_2000_ = +66 09 34, and 
RX J1757.9+6609  RA_2000_ = 17 58 00.6, DE_2000_ = +66 07 35) that are located 
RX J1757.9+6609  36" and 106" away from the X-ray centroid, respectively, are 
RX J1757.9+6609  concordant with the redshift of NEP super cluster (z=0.089) 
RX J1757.9+6609  found in the NEP survey by Mullis et al. (2001, Ph.D. thesis, 
RX J1757.9+6609  Inst. for Astronomy, Univ. Hawaii). 
RX J1758.9+6520 This source is identified with a cluster of galaxies at 
RX J1758.9+6520  z=0.3652. Three cluster galaxies spectroscopically observed 
RX J1758.9+6520  have narrow emission lines (see Fig. 7 for an example of one 
RX J1758.9+6520  cluster member, namely, galaxy C at RA_2000_ = 17 58 53.8, 
RX J1758.9+6520  DE_2000_ = +65 21 02, z_C_=0.3665). A fourth object in the 
RX J1758.9+6520  field at RA_2000_ = 17 59 02.8, DE_2000_ = +65 20 55, has broad
RX J1758.9+6520  emission lines and is thus identified as AGN1 (z=0.3660). The 
RX J1758.9+6520  identification of the source is still a cluster of galaxies 
RX J1758.9+6520  based on the distance of the AGN1 from the X-ray position 
RX J1758.9+6520  (~35"), but a contribution to the X-ray emission from the AGN1 
RX J1758.9+6520  is not excluded. Thus, this source is a case of cluster 
RX J1758.9+6520  plus AGN. 
RX J1759.7+6629 This X-ray source (AGN1 at z=0.399) was already identified by 
RX J1759.7+6629  Bower et al. (1996MNRAS.281...59B). We took an additional 
RX J1759.7+6629  spectrum to confirm the QSO nature. 
RX J1800.0+6645 This X-ray source is the same as RX J1800.0+6646 in Bower et al.
RX J1800.0+6645  (1996MNRAS.281...59B) and was identified as a G type star. Our 
RX J1800.0+6645  spectrum confirms that the object is a G-K type star. 
RX J1800.1+6636 This X-ray source was already identified by Bower et al. 
RX J1800.1+6636  (1996MNRAS.281...59B) as a Sy2 galaxy (NGC 6552). We took an 
RX J1800.1+6636  additional spectrum (z=0.0260) to confirm the AGN2 nature. 
RX J1801.2+6902 The redshift for this source (AGN1, z=1.27) comes from Lacy et 
RX J1801.2+6902  al. (1993MNRAS.263..707L). 
RX J1801.2+6624 This X-ray source was already identified in Bower et al. 
RX J1801.2+6624  (1996MNRAS.281...59B) as a QSO at z=1.25. 
RX J1801.7+6638 This is a bright X-ray source identified as a BL Lac in Bower et
RX J1801.7+6638  al. (1996MNRAS.281...59B; see finding chart in their Fig. 2c 
RX J1801.7+6638  and an optical spectrum in their Fig. 6). The redshift is 
RX J1801.7+6638  unknown since the optical spectrum is featureless. A radio 
RX J1801.7+6638  source (1.07+/-0.04mJy at 6cm) was detected with the VLA in the
RX J1801.7+6638  DnC array at the position of the optical source by T. Rector 
RX J1801.7+6638  (2003, private communication). 
RX J1802.0+6629 This source was identified as a BL Lac in Bower et al. 
RX J1802.0+6629  (1996MNRAS.281...59B) given the very weak or almost absent 
RX J1802.0+6629  lines in the spectrum they obtained at the Multiple Mirror 
RX J1802.0+6629  Telescope (see their Fig. 3). An optical spectrum of this same 
RX J1802.0+6629  source was obtained by us in 1999 July with KeckII-LRIS (see 
RX J1802.0+6629  Fig. 12). Strong and broad Balmer emission lines are visible in
RX J1802.0+6629  our spectrum consistent with an AGN1 object, possibly a 
RX J1802.0+6629  variable QSO? 
RX J1802.7+6727 This source is identified as an AGN2 at z=0.1620. There are two 
RX J1802.7+6727  possibly interacting spiral galaxies with optical narrow 
RX J1802.7+6727  emission lines in their spectra, which are blended on the APM 
RX J1802.7+6727  finder. The optical position of galaxy A1, at (z=0.1605), is 
RX J1802.7+6727  RA_2000_ = 18 02 47.8, DE_2000_ = +67 27 41, while the optical 
RX J1802.7+6727  position of galaxy A2, at z=0.1635, is RA_2000_ = 18 02 47.6, 
RX J1802.7+6727  DE_2000_ = +67 27 34. Both galaxies could be responsible for 
RX J1802.7+6727  part of the X-ray emission. 
RX J1803.4+6738 This very bright NEP source is MS 1803+6728 and is identified as
RX J1803.4+6738  AGN1. The redshift (z=0.1360) was measured by Stocke et al. 
RX J1803.4+6738  (1991ApJS...76..813S). The object is also listed in the QSO 
RX J1803.4+6738  catalog by Hewitt & Burbidge (Cat. VII/158) as HB89, and
RX J1803.4+6738  in the X-ray NORAS catalog by Boehringer et al. 
RX J1803.4+6738  (2000ApJS..129..435B) as a tentative AGN. Optical spectra taken
RX J1803.4+6738  at Lick and Multiple Mirror Telescope observatories are shown 
RX J1803.4+6738  in Figure 4 of Treves et al. (1995ApJ...442..589T). 
RX J1803.9+6548 The redshift for this BL Lac (z=0.0850) is tentative since it 
RX J1803.9+6548  has been derived from very weak absorption lines. The source is
RX J1803.9+6548  also identified with the VLA radio source NEP J1803.9+6548 by 
RX J1803.9+6548  Kollgaard et al. (1994ApJS...93..145K), and it is in the 
RX J1803.9+6548  radio-loud ROSAT NEP sources detected with the VLA at 1.5GHz 
RX J1803.9+6548  by Brinkmann et al. (1999A&AS..134..221B) with a 
RX J1803.9+6548  flux =43.1+/-1.7mJy (see more references therein). 
RX J1804.3+6629 This source is identified with a very hot, subdwarf star. Its 
RX J1804.3+6629  optical position, RA_2000_ = 18 04 24.7, DE_2000_ = +66 29 28, 
RX J1804.3+6629  is 26" away from the X-ray position. There is a second object 
RX J1804.3+6629  in the field that is closer (RA_2000_ = 18 04 20.6, 
RX J1804.3+6629  DE_2000_ = +66 29 54) to the center of the X-ray emission and 
RX J1804.3+6629  for which no spectrum is available. However, this second object
RX J1804.3+6629  is quite faint, is not blue on the DSS, does not have any 
RX J1804.3+6629  radio emission, and thus is unlikely to be an AGN. 
RX J1806.1+6813 This source is identified as cluster of galaxies at z=0.303. 
RX J1806.1+6813  Four out of six galaxies for which we have taken spectra are 
RX J1806.1+6813  emission-line galaxies, all with concordant redshifts. One of 
RX J1806.1+6813  the four galaxies (RA_2000_ = 18 06 04.8, DE_2000_ = +68 13 08,
RX J1806.1+6813  z=0.2953) has broad Balmer (FWHM=2500km/s). Thus, this source 
RX J1806.1+6813  is a case of cluster plus AGN. 
RX J1806.4+7028 This source is identified as a galaxy and has an X-ray 
RX J1806.4+7028  luminosity L_X_=1.8x10^43^erg/s (assuming kT=2keV), which is 
RX J1806.4+7028  high for a galaxy with no emission lines. As first noted by 
RX J1806.4+7028  Mullis (2001, Ph.D. thesis, Inst. for Astronomy, Univ. Hawaii) 
RX J1806.4+7028  it could be an example of overluminous galaxies found in X-ray 
RX J1806.4+7028  surveys (e.g., Vikhlinin et al. 1999ApJ...520L...1V and 
RX J1806.4+7028  references therein). 
RX J1806.8+6949 This is a BL Lac in a cluster of galaxies. Redshift comes from 
RX J1806.8+6949  Falco et al. (1999PASP..111..438F). 
RX J1808.8+6634 The redshift for this source, identified as AGN1 at z=0.697, 
RX J1808.8+6634  comes from Laurent-Muehleisen et al. (1998ApJS..118..127L). 
RX J1808.8+6634  See their Table 2 for source properties. 
RX J1810.3+6328 This source, identified as AGN1 at z=0.838, has a double 
RX J1810.3+6328  morphology in X-rays. The identification of the X-ray source 
RX J1810.3+6328  given in Table 3 refers to the western lobe 
RX J1810.3+6328  (RA_2000_ = 18 10 31.1, DE_2000_ = +63 28 08, z=0.838). The 
RX J1810.3+6328  eastern lobe is an AGN1 at z=1.0907 (RA_2000_ = 18 10 16.9, 
RX J1810.3+6328  DE_2000_ = +63 29 14). 
RX J1815.4+6806 The redshift for this QSO (z=0.239) comes from Lacy et al. 
RX J1815.4+6806  (1993MNRAS.263..707L). 
RX J1821.9+6420 The identification of this source as a QSO at z=0.2970 comes 
RX J1821.9+6420  from Pravdo & Marshall (1984ApJ...281..570P; see an optical 
RX J1821.9+6420  spectrum in their Fig. 2). However, as already noted by 
RX J1821.9+6420  Hutchings & Neff (1991AJ....101.2001H, see their Fig. 1), a 
RX J1821.9+6420  cluster of galaxies for which six galaxy spectra were taken by 
RX J1821.9+6420  Schneider et al. (1992AJ....103.1047S) is present at the same 
RX J1821.9+6420  redshift as the QSO (see detailed description of this 
RX J1821.9+6420  QSO/cluster source in Wold et al., 2002MNRAS.335.1017W and 
RX J1821.9+6420  references therein). The X-ray source has the highest S/N of 
RX J1821.9+6420  the whole NEP survey, it is extremely X-ray luminous 
RX J1821.9+6420  (L_X_=5.61x10^45^erg/s), and it is also an IRAS source, as 
RX J1821.9+6420  reported by de Grijp et al. (1992A&AS...96..389D). 
RX J1826.6+6706 This source is identified with an AGN1 at z=0.287. The redshift 
RX J1826.6+6706  comes from Lacy et al. (1993MNRAS.263..707L). 
RX J1832.5+6848 This source is identified as a cluster of galaxies at z=0.205. 
RX J1832.5+6848  We took optical spectra for three galaxies and they have 
RX J1832.5+6848  concordant redshifts. The source is listed in the literature as
RX J1832.5+6848  the radio source 7C 1832+6845, and it is identified as QSO by 
RX J1832.5+6848  Veron-Cetty & Veron (2001A&A...374...92V), and as BL Lac in the
RX J1832.5+6848  NORAS catalog by Boehringer et al. (2000ApJS..129..435B). The 
RX J1832.5+6848  ambiguity may be due to the fact that there are two distinct 
RX J1832.5+6848  objects very closely separated (~6") at the position of the 
RX J1832.5+6848  X-ray source. The northwest object, object A, is the object we 
RX J1832.5+6848  have observed spectroscopically (RA_2000_ = 18 32 35.6, 
RX J1832.5+6848  DE_2000_ = +68 48 09, z=0.2049). It is red on the DSS, and its 
RX J1832.5+6848  spectrum shows narrow Balmer and oxygen emission lines, 
RX J1832.5+6848  consistent with an AGN2 object (unless we caught the QSO in a 
RX J1832.5+6848  quiescent state). The southeast object A1 
RX J1832.5+6848  (RA_2000_ = 18 32 36.2, DE_2000_ = +68 48 04) appears blue on 
RX J1832.5+6848  the DSS and could be the object indicated as QSO or BL Lac in 
RX J1832.5+6848  the literature. No spectrum is available for A1. A second 
RX J1832.5+6848  galaxy in the cluster (object B at RA_2000_ = 18 32 35.9, 
RX J1832.5+6848  DE_2000_ = +68 47 43, z=0.2048) also shows narrow emission 
RX J1832.5+6848  lines and it is classified as AGN2 in the cluster. The third 
RX J1832.5+6848  galaxy for which we obtained a spectrum, object C 
RX J1832.5+6848  (RA_2000_ = 18 32 35.6, DE_2000_ = +68 47 58, z=0.2054), shows 
RX J1832.5+6848  no emission lines in its spectrum. 
RX J1834.1+7057 This source is very extended in X-rays, and it is identified 
RX J1834.1+7057  with a cluster of galaxies at z=0.0803. An extraction radius of
RX J1834.1+7057  6.5' has been used, different from the normal 5' radius used 
RX J1834.1+7057  for the rest of the X-ray sources. The X-ray position is 
RX J1834.1+7057  centered on a bright galaxy (RA_2000_ = 18 34 08.5, 
RX J1834.1+7057  DE_2000_ = +70 57 19, m_E_=~12.5), possibly the cD, whose 
RX J1834.1+7057  redshift appears in the NORAS catalog of Boehringer et al. 
RX J1834.1+7057  (2000ApJS..129..435B) as z=0.0824. The source is in the same 
RX J1834.1+7057  region of sky as A2308, even if the Abell cluster position in 
RX J1834.1+7057  the NED database is at RA_2000_ = 18 33 33.8 and 
RX J1834.1+7057  DE_2000_ = +71 01 28. The redshift given in Table 3 has been 
RX J1834.1+7057  computed using spectra for three galaxies taken by us at the 
RX J1834.1+7057  UH 2.2m. The redshift agrees with other redshift determinations
RX J1834.1+7057  listed in NED for A2308. 
RX J1842.5+6809 Redshift for this AGN1, z=0.4750, comes from the literature. The
RX J1842.5+6809  QSO is listed in the catalog by Hewitt & Burbidge (Cat. VII/158
RX J1842.5+6809  1993ApJS...87..451H ) and in Xu et al. (1994AJ....108..395X).