2021A&A...648A.125G

Query : 2021A&A...648A.125G

2021A&A...648A.125G - Astronomy and Astrophysics, volume 648A125-125 (2021/4-1)

Characterizing the astrometric instability of extragalactic radio source positions measured with geodetic VLBI.

GATTANO C. and CHARLOT P.

Abstract (from CDS):


Context. Geodetic very long baseline interferometry (VLBI) has been used to observe extragalactic radio sources for more than 40 yr. The absolute source positions derived from the VLBI measurements serve as a basis to define the International Celestial Reference Frame (ICRF). Despite being located at cosmological distances, an increasing number of these sources are found to show position instabilities, as revealed by the accumulation of VLBI data over the years.
Aims. We investigate how to characterize the astrometric source position variations, as measured with geodetic VLBI data, in order to determine whether these variations occur along random or preferential directions. The sample of sources used for this purpose is made up of the 215 most observed ICRF sources.
Methods. Based on the geodetic VLBI data set, we derived source coordinate time series to map the apparent trajectory drawn by the successively measured positions of each source in the plane of the sky. We then converted the coordinate time series into a set of vectors and used the direction of these vectors to calculate a probability density function (PDF) for the direction of variation of the source position. For each source, a model that matches the PDF and that comprises the smallest number of Gaussian components possible was further adjusted. The resulting components then identify the preferred directions of variation for the source position.
Results. We found that more than one-half of the sources (56%) in our sample may be characterized by at least one preferred direction. Among these, about three-quarters are characterized by a unique direction, while the remaining sources show multiple preferred directions. The analysis of the distribution of these directions reveals an excess along the declination axis that is attributed to a VLBI network effect. Whether single or multiple, the identified preferred directions are likely due to source-intrinsic physical phenomena.

Abstract Copyright: © C. Gattano and P. Charlot 2021

Journal keyword(s): astrometry - reference systems - galaxies: nuclei - quasars: general - techniques: interferometric

Simbad objects: 217

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Number of rows : 217
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 QSO B0003-066 BLL 00 06 13.89288482 -06 23 35.3353584   19.1 18.50 17.14   ~ 346 1
2 QSO B0008-264 BLL 00 11 01.24673726 -26 12 33.3771340   19.53   19.64   ~ 86 1
3 6C 001403+811827 BLL 00 17 08.47489694 +81 35 08.1365094   17.60 16.52 15.95   ~ 405 1
4 QSO J0019+2021 BLL 00 19 37.85449305 +20 21 45.6446105     20.6 19.70   ~ 90 1
5 QSO B0016+73 Bla 00 19 45.78637230 +73 27 30.0176020     19.00 18.26   ~ 313 1
6 QSO B0019+058 BLL 00 22 32.44121084 +06 08 04.2689202   19.2   19.07   ~ 152 1
7 QSO B0048-09 BLL 00 50 41.3172421464 -09 29 05.210474100 16.74 16.39 16.22 16.14   ~ 480 2
8 7C 0059+5808 Bla 01 02 45.76237340 +58 24 11.1366164   20.09 19.22 18.57 17.90 ~ 262 1
9 QSO B0104-408 Bla 01 06 45.10796439 -40 34 19.9603733   18.60 19.0 19.25   ~ 136 1
10 4C 01.02 Bla 01 08 38.77110544 +01 35 00.3171844   18.54 18.39 19.05   ~ 589 1
11 UGC 773 BLL 01 13 43.14494773 +02 22 17.3162687   16.4 16.0 11.22   ~ 145 1
12 ICRF J011748.7-211106 Bla 01 17 48.78013249 -21 11 06.6332076   21.85   20.03   ~ 60 1
13 QSO B0119+115 Bla 01 21 41.59504128 +11 49 50.4132344   19.5 19.70 18.61   ~ 200 1
14 QSO B0119+041 Bla 01 21 56.86169274 +04 22 24.7342932   19.2 19.5 19.40   ~ 200 1
15 QSO B0131-522 Bla 01 33 05.76250002 -52 00 03.9454078   18.68 20.3 18.63   ~ 129 1
16 6C 013354+473615 Bla 01 36 58.59480326 +47 51 29.1000720     19.50 19.25 15.21 ~ 537 1
17 ICRF J013708.7+312235 Bla 01 37 08.73363213 +31 22 35.8555330       20.70   ~ 42 0
18 QSO B0201+113 Bla 02 03 46.65705710 +11 34 45.4094619   19.5 19.5 19.41   ~ 216 1
19 4C 15.05 Bla 02 04 50.41389294 +15 14 11.0436097   21.9 21.00 21.00   ~ 426 1
20 7C 020209.69+315812.00 Bla 02 05 04.92536206 +32 12 30.0954703     17.40 17.40   ~ 246 1
21 QSO B0208-512 BLL 02 10 46.2004407600 -51 01 01.893013392   17.10 16.93 14.82   ~ 485 1
22 6C 021252+733537 BLL 02 17 30.81335327 +73 49 32.6217355     19.00 18.97   ~ 485 1
23 QSO J0217+0144 Bla 02 17 48.95475095 +01 44 49.6990271   16.74 16.09 18.51 13.29 ~ 455 1
24 4C 13.14 Bla 02 31 45.89405619 +13 22 54.7162847   17.96 17.71 17.93   ~ 291 1
25 4C 28.07 Bla 02 37 52.40567519 +28 48 08.9899986     19.30 16.99   ~ 654 1
26 QSO B0235+1624 BLL 02 38 38.93010450 +16 36 59.2745528   16.46 15.50 15.92   ~ 1614 2
27 QSO B0237-027 Bla 02 39 45.47227239 -02 34 40.9145702   19.5 21 19.04   ~ 145 1
28 NGC 1052 Bla 02 41 04.79849989 -08 15 20.7519527 11.84 11.41 10.47 10.71   ~ 1397 2
29 4C 47.08 BLL 03 03 35.24221958 +47 16 16.2754726   17.54 16.95 16.2   ~ 292 1
30 QSO B0308-611 Bla 03 09 56.09914475 -60 58 39.0564095   19.00 18.5 18.18   ~ 154 1
31 [VV96] J031049.8+381453 BLL 03 10 49.87992240 +38 14 53.8378761     19.70 19.21   ~ 127 1
32 NGC 1275 Bla 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 4243 3
33 QSO J0325+2224 Bla 03 25 36.81435345 +22 24 00.3656161     18.90 19.14   ~ 135 1
34 QSO B0332-403 BLL 03 34 13.65448823 -40 08 25.3979928 18.54 18.35 17.87 17.5   ~ 349 1
35 QSO B0336-0156 Bla 03 39 30.93778633 -01 46 35.8041892   18.96 18.41 17.33   ~ 598 1
36 6C 034547+460053 QSO 03 49 18.74157513 +46 09 59.6578198           ~ 34 1
37 6C 035545+504923 Bla 03 59 29.74727351 +50 57 50.1618607           ~ 480 1
38 QSO J0403-3605 Bla 04 03 53.74990003 -36 05 01.9131880   17.04 17.17 16.67   ~ 313 1
39 ICRF J040549.2+380332 SyG 04 05 49.26287155 +38 03 32.2348497   18.5 18.5     ~ 187 3
40 QSO B0405-385 Bla 04 06 59.03533781 -38 26 28.0423651   19.55 18.0     ~ 250 2
41 QSO B0420-0127 Bla 04 23 15.80072217 -01 20 33.0656073   17.50 17.00 16.28   ~ 1263 3
42 QSO B0434-188 Bla 04 37 01.48273617 -18 44 48.6135530   19.11 19.0 19.62   ~ 111 1
43 QSO B0446+113 BLL 04 49 07.67110194 +11 21 28.5963618     20.00 18.58   ~ 305 1
44 QSO J0457-2324 Bla 04 57 03.1791422424 -23 24 52.021129572   18.85 18.5 16.56   ~ 435 1
45 4C -02.19 Bla 05 01 12.80988538 -01 59 14.2564557   19.1 18.06 19.04   ~ 624 1
46 QSO B0454+844 BLL 05 08 42.36351222 +84 32 04.5441733     16.5 18.95   ~ 250 1
47 ICRF J052930.0-724528 QSO 05 29 30.04217573 -72 45 28.5075004   19.61       ~ 102 1
48 QSO J0530+13 Bla 05 30 56.41674741 +13 31 55.1494688     20.00 19.35   ~ 1004 1
49 6C 052927+482100 Bla 05 33 15.86579115 +48 22 52.8077787     19.90     ~ 150 1
50 QSO B0537-441 BLL 05 38 50.36155950 -44 05 08.9390233   15.77 16.48 16   ~ 924 2
51 QSO B0537-286 Bla 05 39 54.28147904 -28 39 55.9481236   19.70 20.0 18.789   ~ 314 1
52 NVSS J054734+272157 Rad 05 47 34.14892156 +27 21 56.8425747           ~ 44 1
53 7C 055201.39+394824.00 Bla 05 55 30.80561419 +39 48 49.1649683     18.30 17.5   ~ 527 2
54 NVSS J055932+235354 Rad 05 59 32.03313313 +23 53 53.9267334           ~ 52 1
55 6C 060237+672110 Bla 06 07 52.67161421 +67 20 55.4100806   20.6 20.6 20.21   ~ 103 1
56 QSO B0606-223 Bla 06 08 59.68684160 -22 20 20.9567640   21.14 20.0 20.5   ~ 75 1
57 QSO B0607-157 Bla 06 09 40.94954062 -15 42 40.6727537   18.47 18.00 19.90   ~ 330 1
58 QSO J0635-7516 Bla 06 35 46.5079301472 -75 16 16.816418256   15.96 15.75 15.82   ~ 625 1
59 6C 064126+391750 Bla 06 44 53.70959953 +39 14 47.5339198     20.30 19.47   ~ 57 1
60 7C 064253.00+445430.00 Bla 06 46 32.02599653 +44 51 16.5901185   19.57 18.49 18.64   ~ 370 1
61 QSO J0650-1637 QSO 06 50 24.58185949 -16 37 39.7255562   22.09       ~ 125 1
62 ICRF J065917.9+081330 QSO 06 59 17.99603181 +08 13 30.9534246           ~ 38 1
63 ICRF J070001.5+170921 QSO 07 00 01.52554306 +17 09 21.7013068   21.0       ~ 89 1
64 8C 0716+714 BLL 07 21 53.4482942664 +71 20 36.363846516   15.5 15.50 14.27   ~ 1388 1
65 ICRF J072611.7+791131 Bz? 07 26 11.73523889 +79 11 31.0162113       23.08   ~ 53 0
66 QSO J0730-116 Bla 07 30 19.11247452 -11 41 12.6006642     20.30 20.3   ~ 323 1
67 QSO J0738+1742 BLL 07 38 07.39375312 +17 42 18.9981506   16.76 16.22 15.78   ~ 1045 1
68 QSO B0736+01 Bla 07 39 18.03389906 +01 37 04.6177501   16.90 16.47 16.19   ~ 738 1
69 QSO B0742+103 Bla 07 45 33.05952486 +10 11 12.6922178     24.00 23.72   ~ 200 1
70 [VV2006] J074625.9+254901 Bla 07 46 25.87418071 +25 49 02.1347101   19.94 19.69 19.2   ~ 186 2
71 QSO B0748+126 Bla 07 50 52.04573865 +12 31 04.8282079   17.67 17.28 17.16   ~ 363 1
72 4C 54.15 BLL 07 53 01.38457270 +53 52 59.6370830   18.5   16.77   ~ 173 1
73 6C 080047+615309 Bla 08 05 18.17956222 +61 44 23.7005580       19.64   ~ 154 1
74 7C 080458.39+495918.00 Bla 08 08 39.66628970 +49 50 36.5304041   19.55 19.18 18.34   ~ 389 2
75 7C 080533.60+410130.00 Bla 08 08 56.65204477 +40 52 44.8888932   19.87 19.41 16.61   ~ 149 1
76 QSO B0808+019 BLL 08 11 26.70731711 +01 46 52.2201568   17.58 17.2 17.96   ~ 281 1
77 7C 081451.89+423206.00 BLL 08 18 15.99961476 +42 22 45.4148987   18.88 18.18 17.81   ~ 429 1
78 4C 39.23A Bla 08 24 55.48385834 +39 16 41.9040476   18.55 18.21 17.20   ~ 238 1
79 QSO B0823+033 BLL 08 25 50.33835759 +03 09 24.5199749   17.81 17.23 16.91   ~ 352 1
80 7C 082754.29+242103.00 Bla 08 30 52.08619250 +24 10 59.8202919   17.62 17.26 16.30   ~ 563 1
81 QSO B0834-201 Bla 08 36 39.21525204 -20 16 59.5042773   19.45 19.4 18.76   ~ 224 1
82 PG 0851+202 BLL 08 54 48.8749846272 +20 06 30.639583620   15.649 15.146 15.446   ~ 2513 1
83 QSO B0912+029 Bla 09 14 37.91343881 +02 45 59.2464510   19.94 19.74 19.2   ~ 115 1
84 QSO B0919-260 Bla 09 21 29.35386197 -26 18 43.3863288   18.46 18.41 18.01   ~ 144 1
85 QSO B0920-397 Bla 09 22 46.41826886 -39 59 35.0682386   18.12 18.8     ~ 143 1
86 6C 092005+390241 Bz? 09 23 14.45293735 +38 49 39.9100905           ~ 51 1
87 4C 39.25 Bla 09 27 03.01394144 +39 02 20.8518067   17.17 17.00 16.486   ~ 1036 1
88 QSO B0925-2021 Bla 09 27 51.82432394 -20 34 51.2325545   16.59 16.40 16.00   ~ 181 2
89 7C 095359.3+252945 Bla 09 56 49.87537985 +25 15 16.0498155   17.46 17.21 17.96   ~ 367 2
90 US 1139 Bla 09 58 19.67164698 +47 25 07.8424065   18.78 18.62 18.39   ~ 264 1
91 6C 095456+654857 BLL 09 58 47.2451872176 +65 33 54.819354600     17.0 15.75   ~ 771 1
92 QSO J1007+1356 Bla 10 07 41.49808928 +13 56 29.6007670     19.0 18.59   ~ 131 1
93 QSO B1034-293 Bla 10 37 16.07974265 -29 34 02.8134977   16.46 16.46 17.54   ~ 358 1
94 6C 103844+524909 Bla 10 41 46.78165398 +52 33 28.2317956   16.96 18.5 16.39   ~ 144 1
95 ICRF J104309.0+240835 BLL 10 43 09.03578135 +24 08 35.4094642   17.98 17.32 16.40   ~ 171 1
96 6C 104451+715930 Bla 10 48 27.61992778 +71 43 35.9384142     19.0 17.49   ~ 270 1
97 6C 105327+702759 Bla 10 56 53.61750640 +70 11 45.9155652   18.5 18.5 19.32   ~ 124 1
98 QSO J1058+8114 Bla 10 58 11.53538897 +81 14 32.6751532   18.5 20.0 18.14   ~ 120 1
99 4C 01.28 BLL 10 58 29.60520810 +01 33 58.8237454   18.74 18.28 16.68   ~ 828 2
100 QSO B1057-797 BLL 10 58 43.30979475 -80 03 54.1598058   19.08   17.31   ~ 211 1
101 Z 184-50 BLL 11 04 27.3140835504 +38 12 31.798495872   13.50 12.90 8.31   ~ 2841 1
102 QSO B1104-445 Bla 11 07 08.69412105 -44 49 07.6183013   17.84 18.2 17.37   ~ 260 1
103 CTD 74 Bla 11 25 53.71191677 +26 10 19.9787016   18.62 18.51 18.39   ~ 158 1
104 QSO B1124-186 Bla 11 27 04.39245388 -18 57 17.4418445   19.17 18.65 19.23   ~ 254 1
105 7C 112812.59+383153.00 Bla 11 30 53.28261620 +38 15 18.5469361   19.11 18.80 19.42   ~ 233 1
106 [VV2006] J113624.5-033029 Bla 11 36 24.57693472 -03 30 29.4966741   19.81 19.47 18.7   ~ 56 1
107 6C 114419+401458 Bla 11 46 58.29791724 +39 58 34.3043988   18.80 18.45 18.58   ~ 261 1
108 QSO B1144-3755 BLL 11 47 01.37071212 -38 12 11.0235229   19.03 16.2 16.72   ~ 320 1
109 QSO B1149-084 Bla 11 52 17.20951637 -08 41 03.3139769     18.50 18   ~ 123 1
110 Ton 599 Bla 11 59 31.83391383 +29 14 43.8268224   14.80 14.41 17.652 13.39 ~ 989 1
111 QSO B1213-172 QSO 12 15 46.75176509 -17 31 45.4031219     21.40 17.50   ~ 151 1
112 4C 04.42 Bla 12 22 22.54962606 +04 13 15.7760715   17.88 17.98 17.06   ~ 354 1
113 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 6022 1
114 M 87 AGN 12 30 49.42338414 +12 23 28.0436859 10.16 9.59 8.63   7.49 ~ 7815 3
115 QSO J1246-0730 Bla 12 46 04.23211565 -07 30 46.5746985   17.6 18.0 18.2   ~ 198 1
116 QSO J1246-2547 Bla 12 46 46.80203943 -25 47 49.2889822   17.65 17.41 16.96 15.5 ~ 314 1
117 3C 279 Bla 12 56 11.16657958 -05 47 21.5251510   18.01 17.75 15.87   ~ 3205 2
118 QSO B1255-316 Bla 12 57 59.06083282 -31 55 16.8516590   19.06   17.86   ~ 108 1
119 7C 130046.50+580438.00 Bla 13 02 52.46528286 +57 48 37.6093029   20.47 19.76 20.63   ~ 124 1
120 US 371 BLL 13 10 28.66385420 +32 20 43.7828340   15.61 15.24 17.91   ~ 917 1
121 QSO B1313-333 Bla 13 16 07.98594757 -33 38 59.1726741   18.04 20.0 17.23   ~ 267 1
122 QSO B1324+224 Bla 13 27 00.86131319 +22 10 50.1628385     18.90 18.80   ~ 194 1
123 QSO B1334-127 Bla 13 37 39.78278132 -12 57 24.6933925   18.5 19.00 16.22   ~ 540 1
124 7C 134218.60+661725.00 Bla 13 43 45.95958219 +66 02 25.7451139   19.93 19.67 18.87   ~ 78 1
125 QSO B1351-018 Bla 13 54 06.89532721 -02 06 03.1904962   20.62 19.91 19.277   ~ 177 1
126 6C 135734+765743 Bla 13 57 55.37154275 +76 43 21.0509950     19.0 20.27   ~ 134 1
127 Mrk 668 BLL 14 07 00.39441712 +28 27 14.6901341   16.13 15.35 10.29   ~ 826 3
128 QSO B1406-076 Bla 14 08 56.48120623 -07 52 26.6665312   20.3 18.4     ~ 336 1
129 6C 141804+543700 BLL 14 19 46.5974051952 +54 23 14.787857796   16.17 15.65 14.16   ~ 630 1
130 6C 141743+383524 Bla 14 19 46.61376262 +38 21 48.4750288   19.88 19.66 19.25   ~ 195 1
131 QSO B1424-41 Bla 14 27 56.29756617 -42 06 19.4376238   18.48 17.7 16.30   ~ 547 1
132 QSO B1451-375 Bla 14 54 27.40976313 -37 47 33.1448219   16.36 16.69 16.14   ~ 201 1
133 QSO B1502+1041 Bla 15 04 24.97978391 +10 29 39.1985309   18.97 18.56 18.94   ~ 634 1
134 QSO J1505+0326 Bla 15 05 06.47716039 +03 26 30.8125704   19.02 18.62 17.72   ~ 278 1
135 QSO J1512-0906 Bla 15 12 50.53293048 -09 05 59.8297908   16.74 16.54     ~ 1409 1
136 ESO 514-1 BLL 15 17 41.8134049824 -24 22 19.482207024   15.13 14.00 13.95   ~ 815 3
137 9C J1521+4336 Bla 15 21 49.61387806 +43 36 39.2681695   19.30 18.95 18.09   ~ 129 1
138 7C 1520+3154 Bla 15 22 09.99173254 +31 44 14.3819383   20.45 19.89 19.87   ~ 230 1
139 QSO B1519-273 BLL 15 22 37.67599511 -27 30 10.7855131   18.72 18.5 17.42   ~ 313 1
140 QSO B1546+0246 Bla 15 49 29.43684740 +02 37 01.1632556   17.57 17.42 15.53   ~ 395 1
141 4C 05.64 Bla 15 50 35.26924234 +05 27 10.4483641   19.10 18.73 19.02   ~ 371 1
142 QSO B1555+001 Bla 15 57 51.43397121 -00 01 50.4137827   20.10 19.72 18.75   ~ 188 1
143 4C 10.45 Bla 16 08 46.20318700 +10 29 07.7757424   18.5 18.70 18.03   ~ 409 1
144 6C 161147+342017 Bla 16 13 41.06424322 +34 12 47.9088535   17.98 17.46 17.07   ~ 673 1
145 QSO B1610-771 Bla 16 17 49.27644414 -77 17 18.4675417   19.19 19.0 17.32   ~ 172 1
146 QSO J1619+2247 Bla 16 19 14.82460190 +22 47 47.8509104       20.00   ~ 77 1
147 QSO B1622-253 Bla 16 25 46.89164287 -25 27 38.3268734   21.3 20.6 19.60   ~ 381 1
148 NGC 6251 Bla 16 32 31.96989253 +82 32 16.3999044 15.24 14.66 12.89 7.62   ~ 772 1
149 4C 38.41 Bla 16 35 15.49297809 +38 08 04.5005995   18.14 17.97 17.25   ~ 906 1
150 6C 163718+572618 Bla 16 38 13.45629995 +57 20 23.9789828     16.90 16.94   ~ 381 1
151 6C 163852+395305 Bla 16 40 29.63277140 +39 46 46.0284071   18.4 19.37 18.75   ~ 336 2
152 [VV2006] J164125.2+225704 Bla 16 41 25.22756511 +22 57 04.0327855   19.54 19.30 19.56   ~ 73 1
153 [VV2006] J164202.2-062124 BLL 16 42 02.17771463 -06 21 23.6950367     20.9 19.20   ~ 81 1
154 3C 345 Bla 16 42 58.80997043 +39 48 36.9939552   16.81 16.59 16.84   ~ 1808 3
155 Z 225-7 BLL 16 53 52.21668403 +39 45 36.6088754 14.09 14.15 13.29 8.26   ~ 2304 2
156 QSO J1700-2610 QSO 17 00 53.15406418 -26 10 51.7253944   16.50       ~ 119 2
157 QSO B1705+0152 Bla 17 07 34.41527083 +01 48 45.6993042   18.5 18.9 18.52   ~ 108 1
158 7C 172601.30+453309.00 BLL 17 27 27.65080202 +45 30 39.7312530   19.0 18.10 16.64   ~ 233 2
159 QSO B1730-130 Bla 17 33 02.70578907 -13 04 49.5482119   18 19.50 18.78 17.39 ~ 1198 1
160 4C 51.37 Bla 17 40 36.97784792 +52 11 43.4073694   18.16 18.70 16.73   ~ 441 1
161 QSO B1741-038 Bla 17 43 58.85613537 -03 50 04.6167326     20.40 17.98   ~ 583 1
162 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
163 4C 62.29 QSO 17 46 14.03413499 +62 26 54.7383195   20.91 19.51     ~ 124 1
164 4C 09.57 BLL 17 51 32.81857326 +09 39 00.7284066   17.46 16.78 15.57   ~ 1007 1
165 QSO J1753+2848 Bla 17 53 42.47364223 +28 48 04.9388788   19.6 19.60 20.28   ~ 118 1
166 1RXS J180043.6+782806 BLL 18 00 45.6838528560 +78 28 04.018028016   16.4 15.90 16.134   ~ 793 1
167 ICRF J180242.6-394007 Bla 18 02 42.68005300 -39 40 07.9081646       17.3   ~ 126 1
168 QSO B1758-651 QSO 18 03 23.49665086 -65 07 36.7613089   18.18       ~ 67 1
169 Z 340-35 BLL 18 06 50.6802916920 +69 49 28.109609256   14.77 14.22 11.39   ~ 909 1
170 LB 1086 Bla 18 08 21.88588528 +45 42 20.8664210   19.0 19.3 19.20   ~ 61 1
171 ICRF J181945.3-552120 QSO 18 19 45.39951531 -55 21 20.7453837   19.19 16.0 21.50   ~ 70 1
172 4C 56.27 BLL 18 24 07.06837171 +56 51 01.4908155   18.9 19.30 16.48   ~ 510 1
173 QSO J1848+3219 Bla 18 48 22.08857099 +32 19 02.6037977       18.79   ~ 163 2
174 6C 184914+670207 Bla 18 49 16.07228484 +67 05 41.6802599     16.90 17.45   ~ 305 2
175 QSO B1908-202 Bla 19 11 09.65289294 -20 06 55.1090664   18.21   18.14   ~ 306 1
176 ICRF J191158.2+161146 Bz? 19 11 58.25740170 +16 11 46.8652526           ~ 48 1
177 [VV2006] J192332.2-210433 Bla 19 23 32.18981392 -21 04 33.3331234   15.32 17.50 16.70   ~ 180 3
178 QSO B1921-293 BLL 19 24 51.05595254 -29 14 30.1210248   18.71 18.21 15.07   ~ 918 1
179 ICRF J192559.6+210626 BLL 19 25 59.60535459 +21 06 26.1620257           ~ 212 1
180 4C 73.18 BLL 19 27 48.4947009120 +73 58 01.572558816     16.06 15.11   ~ 562 2
181 QSO B1936-155 Bla 19 39 26.65775171 -15 25 43.0584711   19.44 20.30 18.80   ~ 180 1
182 QSO B1954-388 Bla 19 57 59.81927491 -38 45 06.3558881   18.47 17.07 16.73   ~ 239 1
183 QSO B1958-179 Bla 20 00 57.09043927 -17 48 57.6726139   18.02 18.60 15.33   ~ 288 1
184 QSO J2002+4725 QSO 20 02 10.41824494 +47 25 28.7737471           ~ 46 1
185 8C 2007+777 BLL 20 05 30.9987913056 +77 52 43.248139536     16.5 17.36   ~ 474 1
186 QSO B2008-159 Bla 20 11 15.71092555 -15 46 40.2537406   17.27 18.30 16.35   ~ 186 1
187 QSO J2016+1632 BLL 20 16 13.86003062 +16 32 34.1130371       17.29   ~ 46 1
188 3C 418.0 Bla 20 38 37.03472279 +51 19 12.6624988   21.30 21.00 18.9   ~ 333 1
189 QSO B2052-474 Bla 20 56 16.35980507 -47 14 47.6277179   18.29 19.1 18.07   ~ 341 1
190 QSO B2059+034 Bla 21 01 38.83415344 +03 41 31.3207714   18.13 17.78 17.68   ~ 176 1
191 QSO J2115+295 Bla 21 15 29.41345155 +29 33 38.3669390     19.5 19.26   ~ 201 1
192 QSO J2123+0535 Bla 21 23 44.51739933 +05 35 22.0930238   18.3 20.40 19.86   ~ 320 1
193 QSO B2126-15 Bla 21 29 12.17589329 -15 38 41.0419083   17.61 17.3 17.3   ~ 521 1
194 QSO B2128-123 BLL 21 31 35.2617909696 -12 07 04.795364172   16.33 16.11 15.87   ~ 470 1
195 QSO B2134+0028 Bla 21 36 38.58632232 +00 41 54.2128562   17.30 17.08 17.02   ~ 580 2
196 QSO B2136+1410 Bla 21 39 01.30926630 +14 23 35.9921774     18.90 18.22   ~ 264 1
197 QSO B2141+1730 Bla 21 43 35.54456275 +17 43 48.7875890   15.91 15.73 15.17   ~ 418 1
198 4C 06.69 Bla 21 48 05.45866779 +06 57 38.6041877   16.85 16.47 15.06   ~ 703 1
199 QSO B2149+056 Bla 21 51 37.87549026 +05 52 12.9545152   23.700 22.050 20.850   ~ 120 1
200 NAME BL Lac BLL 22 02 43.2913536816 +42 16 39.979416792   15.66 14.72     ~ 2397 1
201 4C 31.63 BLL 22 03 14.9756830008 +31 45 38.269473228   15.85 15.58 14.33   ~ 523 1
202 QSO B2209+236 Bla 22 12 05.96631459 +23 55 40.5438259   19 20.66 19.69   ~ 257 1
203 QSO B2214+350 BLL 22 16 20.00989880 +35 18 14.1799033   18.0 18.5 17.53   ~ 78 1
204 4C -03.79 Bla 22 18 52.03772044 -03 35 36.8795441   16.93 16.38 16.15   ~ 353 1
205 3C 446 BLL 22 25 47.25929101 -04 57 01.3907626   18.83 18.39 16.3   ~ 863 1
206 QSO B2227-0848 Bla 22 29 40.08433313 -08 32 54.4355294   17.80 17.41 17.81   ~ 391 1
207 6C 222905+693121 BLL 22 30 36.46973826 +69 46 28.0769147     19.6 20.11   ~ 105 1
208 4C 11.69 Bla 22 32 36.40890093 +11 43 50.9040592   17.75 17.33     ~ 1205 2
209 QSO B2232+282 BLL 22 36 22.47084387 +28 28 57.4132050   19.1 19.0 17.60   ~ 306 2
210 QSO J2246-1206 Bla 22 46 18.23197022 -12 06 51.2775983   16.63 16.45 15.99   ~ 293 1
211 3C 454.3 Bla 22 53 57.7480438728 +16 08 53.561508864   16.57 16.10 15.22   ~ 3004 2
212 QSO B2255-2814 Bla 22 58 05.96287687 -27 58 21.2567572   17.34 16.77 17.20   ~ 397 1
213 6C 230937+452727 Bla 23 11 47.40897544 +45 43 56.0164210       19.19   ~ 70 1
214 QSO J2320+0513 QSO 23 20 44.85659166 +05 13 49.9526016   18.6 19.0     ~ 166 1
215 ICRF J232154.9+320407 Bla 23 21 54.95598750 +32 04 07.6225103     18 20   ~ 115 1
216 QSO J2358-1020 Bla 23 58 10.88239662 -10 20 08.6114174   19.16 18.91 18.00   ~ 170 1
217 QSO B2357+385 Bla 23 59 33.18079487 +38 50 42.3182764   19.0 18.0 19.1   ~ 63 1

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