4. Optical and radio identification program

The majority of sources required further work beyond the catalog searches, either because the objects were too faint or because more information on their optical spectra was required to resolve ambiguities.

4.1. Radio maps

I observed all X-ray source positions in a program of short exposures at the Very Large Array Radio Telescope (VLA) in New Mexico. Between 9 September 1995 and 25 October 1995 a total of 20.5 hours were spent in two bands, at 1.425 GHz (L-band) and 8.439 GHz (X-band). I included all source positions in the L-band program and about half of the sources in the X-band observations. Some observations were lost due to technical problems at the telescope and some due to radio interference. In a few cases the detection limit at the source position was strongly limited by side lobes from strong sources outside the primary beam. All observations prior to October 1995 were done in the hybrid AnB configuration resulting in an elliptical beam that varies with the elevation of the object. The remaining observations were conducted in the more extended B configuration, with a more circular beam.

Table 1 (click here) summarizes all fields with detected radio sources detected close enough to the X-ray position to serve as plausible radio counterparts. Table 2 (click here) shows in Col. B if a source position has a successfully reduced radio map associated with it. A successful radio map is one in which the observation is free from major radio interference, was successfully calibrated and cleaned to an acceptable level. The typical root mean square noise level is between 250 and 350Jy at L-band and 150 to 200Jy at X-band. These values are a factor 2-3 higher than the expected theoretical thermal noise. The reasons for the high noise levels are mostly large zenith angles, the increased background in areas close to the galactic plane and confusing sources. Cleaning the images beyond the current noise level proved to be prohibitively expensive in terms of time and was not justified by the objective to find strong isolated sources. All VLA data were reduced and calibrated within the AIPS software packet distributed by the National Radio Astronomy Observatory.

  Table 1:   All detected VLA radio sources. Internal identification number, X-ray position from ROSAT Sky Survey, radio position (3.6cm emission peak if source was detected, else peak of 20cm emission), peak flux per beam and RMS noise in mJy at 20cm and 3.6cm, distance from X-ray position in arcseconds, in this column ``I'' indicates that this source is associated with the X-ray source. Asterisk in peak level: no source. Asterisks in peak and noise columns: no observation

 

X-ray Source Parameters Identification POSS

ID Rate Error HR1 HR2 Name Type m O-E dist B log

30 00 : 10 : 29.3 +20 : 47 : 38 0.035 0.013 1.00 0.28 87GB 17.86 0.56 12.8 LX 0.1

52 01 : 15 : 20.3 +16 : 48 : 19 0.017 0.007 1.00 1.00 new ID K0III 12.91 0.96 38.8 LX -2.2

40 02 : 25 : 05.4 +18 : 46 : 55 0.177 0.029 1.00 0.50 87GB 18.67 1.41 12.2 1.1

74 03 : 17 : 46.2 +10 : 17 : 35 0.011 0.006 1.00 0.34 17.71 1.68 23.6 L -0.5

69 03 : 20 : 38.0 +11 : 24 : 55 0.055 0.011 1.00 0.72 RadioS(*) 19.41 >1.15 3.5 L 0.5

63 03 : 22 : 02.5 +12 : 28 : 45 0.015 0.007 -1.00 * O20.37 <0.37 27.9 L 0.7

73 03 : 22 : 44.3 +10 : 37 : 27 0.015 0.006 0.02 -1.00 SIMBAD(+) M4V V14.6 10.2 L -1.6

64 03 : 23 : 04.0 +12 : 24 : 40 0.019 0.008 -1.00 * O20.17 <0.17 22.2 L 0.7

66 03 : 23 : 22.2 +11 : 41 : 16 0.123 0.018 -0.22 0.26 SIMBAD(+) M4V V12.2 16.6 L -2.5

71 03 : 23 : 30.6 +10 : 48 : 00 0.014 0.006 1.00 -0.32 (*) K3 13.9 2.13 6.2 L -1.9

62 03 : 24 : 10.0 +12 : 37 : 41 0.054 0.012 0.91 -0.08 SAO 93416 K0III-IV V 6.0 1.2 L -4.5

61 03 : 24 : 38.4 +12 : 53 : 39 0.017 0.007 1.00 0.48 18.17 1.15 1.7 L -0.1

68 03 : 25 : 25.2 +11 : 27 : 53 0.013 0.006 1.00 0.64 17.52 1.88 15.0 L -0.5

72 03 : 25 : 48.2 +10 : 47 : 02 0.024 0.008 1.00 0.52 RadioS (*) RadioS 17.85 2.08 26.0 L -0.1

67 03 : 26 : 20.8 +11 : 31 : 00 0.101 0.018 -0.06 -0.01 (*) M4V 14.66 1.56 9.7 L -0.8

65 03 : 26 : 46.1 +12 : 10 : 11 0.015 0.007 0.91 0.62 z=0.21 (*) AGN 18.88 1.63 11.4 L 0.1

70 03 : 28 : 02.2 +11 : 14 : 34 0.065 0.016 -0.35 0.15 binary (*) M4V:e 15.07 2.34 11.0 L -0.8

22 03 : 28 : 58.7 +31 : 14 : 18 0.043 0.011 1.00 0.02 BD+30 547 K0 V10.3 19.9 L -2.9

21 03 : 29 : 14.3 +31 : 22 : 47 0.018 0.008 1.00 0.60 18.40 >2.99 16.1 L 0.0

77 04 : 01 : 10.9 +00 : 04 : 11 0.022 0.010 1.00 0.39 z=0.47 (*) AGN 17.71 0.65 13.0 L -0.2

76 04 : 02 : 42.0 +01 : 59 : 54 0.032 0.011 1.00 0.48 z=0.14 (*) AGN 16.83 1.70 12.7 L -0.4

75 04 : 03 : 14.2 +02 : 15 : 21 0.013 0.007 1.00 1.00 18.09 >3.32 24.2 L -0.3

33 04 : 21 : 45.7 +19 : 34 : 01 0.017 0.007 1.00 0.04 (*) M1.5V:e 14.63 3.98 37.1 L -1.5

34 04 : 22 : 02.6 +19 : 32 : 20 0.037 0.010 1.00 0.47 T-Tauri 48.0 >1.3

37 04 : 22 : 08.4 +19 : 15 : 17 0.116 0.019 -0.25 0.20 EinsteinS M4.5V:e V12.9 6.3 L -1.4

31 04 : 22 : 18.3 +19 : 50 : 47 0.134 0.019 1.00 0.51 QSO 18.8 L

32 04 : 23 : 23.1 +19 : 39 : 40 0.019 0.008 0.01 -1.00 BD+19 708 K2V V 9.4 11.3 L -3.6

42 04 : 27 : 58.5 +18 : 45 : 30 0.020 0.008 -1.00 * HG 7-224 lm V14.3 6.8 L -1.6

44 04 : 27 : 59.4 +18 : 29 : 50 0.027 0.009 -0.15 -1.00 BD+18 639 K2 V10.1 15.8 L -3.2

43 04 : 29 : 00.8 +18 : 40 : 01 0.032 0.010 0.58 0.14 HG 7-237 lm V13.2 25.3 L -1.8

48 04 : 30 : 04.3 +18 : 13 : 42 0.113 0.018 0.96 0.13 G5V:e V10.6 9.4 L -2.3

82 04 : 33 : 24.1 -14 : 22 : 54 0.027 0.013 1.00 -0.18 J15.79 6.5 L -0.9

81 04 : 34 : 26.5 -13 : 34 : 18 0.043 0.016 1.00 0.45 1E0432.1-1341    GV V 9 5.5 L -3.4

83 04 : 35 : 19.7 -14 : 54 : 47 0.089 0.022 0.05 0.35 (*) K6-7 J14.75 13.2 L -0.8

80 05 : 20 : 30.0 -05 : 48 : 18 0.037 0.012 1.00 -0.01 EM* StHA 39 V13.5 15.0 L -1.7

8 09 : 29 : 49.2 +65 : 22 : 53 0.014 0.006 0.48 -1.00 RadioS (*) 16.19 1.55 0.0 LX -1.0

5 09 : 32 : 15.9 +70 : 06 : 35 0.010 0.006 1.00 1.00 20.10 <0.10 27.9 LX 0.4

6 09 : 34 : 17.4 +66 : 21 : 50 0.020 0.009 -0.38 * K0III 13.07 1.79 30.7 LX -2.1

7 09 : 37 : 27.2 +65 : 38 : 28 0.047 0.011 1.00 -0.08 z=0.29,RS(*) AGN 16.52 0.98 5.4 LX -0.3

90 13 : 58 : 17.2 -39 : 45 : 38 0.019 0.012 * * J16.75 7.6 -0.7

87 15 : 19 : 18.4 -29 : 43 : 18 0.045 0.013 0.90 0.60 (*) M0V J13.83 6.0 LX -1.4

84 15 : 37 : 06.5 -24 : 47 : 35 0.041 0.011 1.00 0.77 J16.78 5.8 LX -0.3

86 15 : 41 : 07.1 -26 : 56 : 32 0.035 0.013 0.45 -0.09 (*) K3 J12.18 6.7 LX -2.2

85 15 : 42 : 08.5 -26 : 29 : 17 0.028 0.010 0.99 -0.13 J17.26 17.3 LX -0.3

78 15 : 51 : 00.6 -01 : 41 : 31 0.019 0.008 1.00 -0.28 J21.68 LX 1.3

79 15 : 53 : 22.3 -03 : 01 : 51 0.127 0.019 -0.08 0.07 SAO 140822 F5 V 7.4 16.0 LX -3.6

16 16 : 44 : 19.3 +59 : 57 : 43 0.022 0.005 0.18 0.59 SAO 17203 G5 V 8.1 12.9 LX -4.0

15 16 : 44 : 35.2 +59 : 58 : 43 0.011 0.003 1.00 0.24 17.89 4.25 8.0 LX -0.4

17 16 : 45 : 47.8 +59 : 57 : 36 0.019 0.004 1.00 0.09 z=0.23 (*) AGN 17.31 0.70 13.1 LX -1.1

13 16 : 55 : 33.5 +61 : 39 : 47 0.006 0.002 1.00 0.10 15.68 1.77 24.2 LX -1.6

: : : :

Table 2:   Summary of the identification program of all 89 sources found within the lowest contours of the MBM cloud maps. Columns are: ID: Internal reference number; X-ray source position in equinox 2000.0; Rate: source count rate in ; Error: error in count rate in ; HR1, HR2: hardness ratios (*: source was not detected when data was split into two spectral channels); Name: catalog name of object; Type: Spectral Type; m: visual magnitude of counterpart; O-E: color index from APM scans; dist.: separation between X-ray source and proposed counterpart; B: bands in which the source has been observed at the VLA; log: logarithm of X-ray to optical flux ratio.
not detected in snapshot; in visual binary with M4V. (*): new Identification; (+) new classification

 

X-ray Source Parameters Identification POSS

ID Rate Error HR1 HR2 Name Type m O-E dist B log

14 16 : 58 : 14.4 +60 : 56 : 15 0.011 0.004 -0.25 0.28 16.44 3.01 14.6 LX -1.0

12 16 : 58 : 32.4 +61 : 59 : 46 0.007 0.003 0.76 0.07 RadioS (*) 14.64 2.44 22.4 LX -1.9

9 16 : 59 : 59.2 +62 : 14 : 45 0.009 0.003 0.37 0.51 16.95 1.15 8.4 LX -0.9

11 17 : 00 : 00.1 +62 : 02 : 18 0.014 0.003 0.92 0.18 15.67 0.57 9.3 LX -1.2

10 17 : 01 : 12.1 +62 : 06 : 31 0.043 0.006 0.12 0.28 z=0.32 (*) AGN 15.98 1.51 23.1 LX -0.6

89 19 : 15 : 11.1 -36 : 47 : 17 0.020 0.010 * * J14.00 16.0 LX -1.7

88 19 : 19 : 31.3 -36 : 39 : 25 0.025 0.012 -1.00 * SAO 211169 F7V V 7.2 5.3 LX -4.4

4 19 : 23 : 26.0 +70 : 07 : 48 0.022 0.005 -0.22 0.22 (*) K6-7 7.75 3.04 21.0 LX -4.2

3 19 : 24 : 05.7 +70 : 19 : 56 0.008 0.003 0.91 -0.18 (*) AGN 17.68 3.98 20.5 LX -0.7

2 20 : 45 : 22.1 +81 : 04 : 37 0.039 0.008 -0.38 0.42 SAO 3462 G5 V 9.4 4.3 LX -3.3

1 21 : 59 : 11.8 +82 : 26 : 22 0.011 0.004 1.00 1.00 19.19 2.23 25.4 LX 0.1

26 22 : 59 : 26.9 +24 : 40 : 54 0.023 0.009 0.38 -0.29 (*) K3 12.79 1.88 13.7 LX -2.2

25 23 : 00 : 03.4 +24 : 44 : 51 0.013 0.006 1.00 1.00 87GB RadioS J16.89 1.51 20.0 LX

27 23 : 02 : 10.9 +24 : 17 : 35 0.012 0.006 1.00 -0.08 RadioS (*) RadioS 17.36 0.11 18.2 LX -0.6

24 23 : 02 : 47.5 +24 : 53 : 14 0.018 0.008 -1.00 * (*) M1.5V:e 17.99 2.68 8.7 LX -0.2

23 23 : 03 : 56.6 +25 : 00 : 43 0.017 0.007 1.00 0.41 17.84 1.11 12.3 LX -0.3

60 23 : 04 : 26.3 +12 : 58 : 40 0.015 0.007 1.00 0.00 18.18 0.71 7.6 LX -0.2

57 23 : 04 : 51.9 +14 : 12 : 41 0.014 0.007 1.00 0.14 O21.68 <1.68 28.0 LX 1.2

58 23 : 04 : 57.8 +13 : 43 : 28 0.015 0.007 1.00 -0.18 17.63 2.11 21.0 LX -0.4

59 23 : 05 : 19.3 +13 : 15 : 37 0.015 0.007 1.00 0.40 17.80 2.63 19.8 LX -0.3

55 23 : 05 : 31.1 +15 : 14 : 50 0.011 0.006 0.53 0.61 z=0.07 (*) AGN 18.89 1.29 6.4 LX 0.0

56 23 : 05 : 58.5 +14 : 13 : 25 0.017 0.007 1.00 -0.09 RadioS (*) 16.72 1.78 14.8 LX -0.7

38 23 : 07 : 47.0 +19 : 02 : 46 0.015 0.007 1.00 0.56 16.23 1.54 30.5 LX -1.0

39 23 : 07 : 47.1 +19 : 01 : 17 0.036 0.011 1.00 -0.06 [HB89] 2305+187 QSO 15.80 1.01 21.4 L -0.8

35 23 : 08 : 12.3 +19 : 30 : 09 0.021 0.008 1.00 0.23 18.34 1.11 25.7 L 0.0

53 23 : 08 : 28.1 +15 : 55 : 46 0.019 0.008 0.03 -0.08 19.86 1.75 2.5 LX 0.6

51 23 : 08 : 41.6 +17 : 49 : 02 0.012 0.006 1.00 -1.00 15.79 1.91 28.5 LX -1.2

54 23 : 08 : 42.8 +15 : 32 : 51 0.045 0.012 0.21 -0.64 HD 218539 G0 V 9.7 4.5 LX -3.1

47 23 : 09 : 01.5 +18 : 20 : 21 0.008 0.005 1.00 1.00 BD+17 4873 G5 V 9.2 LX -4.0

28 23 : 09 : 01.8 +23 : 31 : 35 0.027 0.009 1.00 0.53 18.74 1.11 6.8 LX 0.3

46 23 : 09 : 07.4 +18 : 25 : 20 0.030 0.011 -0.03 0.24 HD 218602 G5 16.35 1.51 14.9  X -0.6

29 23 : 09 : 44.7 +22 : 34 : 18 0.019 0.007 1.00 0.47 O21.89 <1.89 17.3 LX 1.4

49 23 : 10 : 59.8 +18 : 08 : 29 0.032 0.010 -1.00 * (*) DC WD 18.00 -0.55 22.0 LX 0.1

45 23 : 11 : 02.7 +18 : 28 : 20 0.012 0.006 0.98 1.00 LX >0.8

50 23 : 12 : 31.2 +18 : 06 : 22 0.010 0.005 1.00 1.00 18.42 1.96 24.3 LX -0.3

36 23 : 12 : 36.6 +19 : 23 : 03 0.025 0.009 0.51 0.20 binary (*) K3-5 LX

19 23 : 25 : 14.6 +33 : 14 : 12 0.021 0.007 0.18 0.13 (*) K3 9.36 1.94 7.8 LX -3.6

20 23 : 25 : 25.8 +33 : 12 : 44 0.016 0.006 -1.00 * (*) K3 10.78 2.43 32.5 LX -3.1

18 23 : 25 : 57.4 +33 : 17 : 19 0.013 0.005 1.00 0.48 18.34 >2.94 8.9 LX -0.2

: : : :

Table 2: continued

4.2. Optical observations

I took optical spectra and CCD images of most sources during 15 observing nights at Mt. Palomar between 28 June 1995 and 27 December 1995. For low resolution spectra of stars brighter than m_V = 16 I used the Echelle spectrograph in the long slit mode at the Palomar 60-inch telescope. For spectra of fainter objects, down to , I used primarily the Double Spectrograph at the Cassegrain focus of the 200-inch Hale telescope. For some fields I also used the COSMIC prime focus instrument at the Hale telescope. The optical data were reduced using standard routines in the IRAF software suite.