Contents

A&A 403, 105-110 (2003)
DOI: 10.1051/0004-6361:20030348

Selecting stable extragalactic compact radio sources from the permanent astrogeodetic VLBI program[*]

M. Feissel-Vernier

Observatoire de Paris/CNRS UMR8630, 61 Av. de l'Observatoire, 75014 Paris, France
Institut Géographique National/LAREG

Received 24 January 2003 / Accepted 25 February 2003

Abstract
A set of stable compact radio sources is proposed, based on the analysis of VLBI-derived time series of right ascensions and declinations from mid-1989 through May 2002. Five selection schemes are tested, that are based on the usual and Allan standard deviations and on apparent drifts. The efficiency of the selection schemes is characterized by the ability of the sources to support the maintenance of the direction of the axes of the celestial reference frame that they materialize. When compared with the current set of ICRF defining sources, the best performing selection scheme keeps 199 sources and lowers the medium-term frame instability from 28 to 6 microarcsec.

Key words: quasars: general - astrometry - reference systems

1 Introduction

The permanent astrogeodetic VLBI observing program started in the 1980s as a joint effort of several institutions, sponsored mainly by the US National Aeronautical and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA). After undergoing development and international extension, it is now managed by the IVS (International VLBI Service for Geodesy and Astrometry). Astrogeodetic VLBI is currently the only available technique to monitor the irregular Earth's rotation at the required level of accuracy. It will stay so in the foreseable future, as no competing technique is proposed. This program provides the basis for the monitoring of the IAU-recommended International Celestial Reference Frame (ICRF, Ma et al. 1998; see also IERS 1999 for the ICRF-Ext.1) to which other celestial reference frames, e.g. the Hipparcos catalogue, are referred.

At the end of 2002, over three million observations of more than 700 compact extragalactic radio sources have been accumulated. This data set includes extremely uneven observation rates. However, about half of the objects are well enough monitored so that the medium and long term stability of their directions can be investigated.

The observed objects are selected by the IVS among quasars and galaxy nuclei that are compact when observed in the X-band (4 cm) and S-band (13 cm) with baseline lengths extending to several thousands kilometers. However, when observed at the current level of precision (a fraction of milliarcsecond, mas), no object is really pointlike. Apparent motions, if existing, may be related to the existence of jets originating in the sources. While the background source structure is assumed to stay fixed, quasi periodical oscillations may exist, as well as apparent drifts that are unlikely to continue indefinitely, but with time characteristics that are not well known.

This observational situation may come into contradiction with the basic assumption that, globally, the set of selected object has a no net rotation relative to the quasi inertial space. However, little is presently known about the actual behaviour of these hundreds of sources, so that the solution to solve this difficulty appears to be the selection of sources that best match the no-motion model, in order to minimize the uncontrolled global rotation. The authors of the ICRF (Ma et al. 1998) set up three classes of sources, using qualitative and quantitative criteria, such as apparent drift, formal uncertainty of the global coordinates over 1980-1995, source stucture index. They used only the sources they considered as the most reliable (the defining sources) for the definition of the ICRF orientation. A second set of apparently reliable sources that had not been well enough observed in 1995 were considered as candidates. Finally, the remaining sources, considered as unstable, were labelled other sources.


  \begin{figure}
\par\includegraphics[width=88mm,clip]{MS3523f1.eps} %
\end{figure} Figure 1: The most observed ICRF radio sources. Total flux at wavelengths 6 cm (vertical bars), and 11 cm or 15 cm (horizontal bars) are shown when available.

In this paper, we study statistical schemes to detect the most stable sources in the available data, that would be used for the maintenance of the ICRF and the monitoring of the Earth's rotation. The study is entirely based on the series of individual source coordinates derived by Fey (2002) over 1979-2002. We extract from this data set the data over 1989.5-2002.4, i.e. 3.1 million observations of 707 sources, representing 87% of the total observations.

2 The observations

The observations consist of time series derived from a set of three analyses of the existing VLBI observing sessions up to May 2002. Each analysis results in time series of coordinates per session for one third of the sources ("arc'' sources), the coordinates of the other sources being treated as "global'', i.e. they are assumed to stay fixed in time and are estimated globally. Each analysis includes a no-net-rotation (NNR) condition with respect to the ICRF based on the ICRF defining sources.

To avoid inconsistencies due to the NNR condition realization in the three analyses, and that reach the level of 50 microarcsec ($\mu $as), we consider here for each source the time series of its coordinate differences with their global weighted mean.

Figure 1 gives the sky distribution of the most observed ICRF radio sources. The mean flux at 6 cm and 11 or 15 cm is shown when available at the IERS Celestial Reference System Product Center (2002). The observation rates histogram are shown in Fig. 2 for the 707 sources.

If the source structure is extended or not circular, its apparent direction may change as a function of the length and orientation of the baselines. Most of the known activity of quasars takes the form of jets, i.e., aligned emissive structures that cause an apparent motion of the observed phase center relative to a fixed background. Therefore, the source structure often changes with time. In principle it is possible to accurately correct this effect, provided that repeated maps of the sources are available (Charlot & Sovers 1997).


  \begin{figure}
\par\includegraphics[width=88mm,clip]{MS3523f2.eps} \end{figure} Figure 2: Observation rates. Number of sessions in which a given source is observed. The leftmost abscissae limit in the right insert is equal to 600.

However, although series of source maps are routinely derived for the northern hemisphere (Fey & Charlot 1997), the source structure correction is not implemented in the existing astrogeodetic analysis software. As a result, most objects exhibit time variations of their position in some preferred direction.

3 Selection schemes

An earlier study (Gontier et al. 2001) has shown that the improvements in VLBI technology, the development of the observing network and the extension of the set of observed objects that took place in operational VLBI, brought the astrometric results to its current precision towards the end of the first decade. Starting about 1990, individual time series of source coordinates stabilize. Therefore, the selection schemes under study are applied to data after 1989.5. Note that values and plots of yearly averages for sources observed since 1984 are available (IERS 2003).

A set of stable sources is selected in a two-step process, based on series of one-year coordinates, obtained as the mean of the sessions's coordinates weighted according to the corresponding uncertainties:

1.
A first selection is made on the basis of continuity criteria for one-year weighted average coordinates.

(a)
Length of observation period longer than five years.
(b)
Not less than two observations of the source in a given session.
(c)
One-year average coordinates based on at least three observations. As this number may be considered as too small, a test was made for comparison with one-year average coordinates based on at least twelve observations.
(d)
Not more than three successive years with no observations, conditions (b) and (c) being met.
(e)
At least half of the one-year averages available over the source observation span.

This first screening keeps 362 sources for the years centered at 1990.0 through 2002.0. These include 141 defining sources, 130 candidates, 87 other and 4 new sources, i.e. 67% of the defining sources, 44% of the candidates and 85% of the others.

2.
The time series of yearly values of $\alpha \cos\delta$ and $\delta$ are then analysed in order to derive
(a)
the linear drift (least squares estimation);
(b)
the standard deviation of a single value referred to its global average, and

(c)
the Allan standard deviation for a one-year sampling time. The Allan variance of a time series xi with N items and sampling time $\tau$ is defined as:


\begin{eqnarray*}\sigma_{\rm A}^2(\tau)=\frac{1}{2N} \sum_i(x_{i+1} - x_i)^2.
\end{eqnarray*}


The Allan variance analysis (Allan 1966, see a review of these methods in Rutman 1978) allows one to characterize the power spectrum of the variability in time series, for sampling times ranging from the initial interval of the series to 1/4 to 1/3 of the data span, in our case one year through four years. This method allows one to identify white noise (spectral density S independent of frequency f), flicker noise (S proportional to f-1), and random walk (S proportional to f-2). Note that one can simulate flicker noise in a time series by introducing steps of random amplitudes at random dates. In the case of a white noise spectrum (an implicit hypothesis in the current ICRF computation strategy), accumulating observations with time eventually leads to the stabilisation of the mean position. In the case of flicker noise, extending the time span of observation does not improve the quality of the mean coordinates. A convenient and rigorous way to relate the Allan variance of a signal to its error spectrum is the interpretation of the Allan graph, which gives the changes of the Allan variance for increasing values of the sampling time $\tau$. In logarithmic scales, slopes -1, 0 and +1 correspond respectively to white noise, flicker noise and random walk noise.

The distributions of the above statistics applied to the 362 preselected sources are shown in Fig. 3. The normalized linear drift is the absolute value of the least-square derived linear drift divided by its formal uncertainty. This unitless number measures the degree of statistical significance of the estimated velocity. Note that the histograms are quite similar for right ascensions and declinations, except for the standard deviations of the one-year average coordinates, where the declinations tend to be noisier than right ascensions. This may be related to analysis difficulties remaining after the sizeable improvement that was brought to the declination determinations by the adoption of the gradient function correction (McMillan & Ma 1997).

Based on these statistics, rules are set up to derive source stability indices. For each local coordinate ( $\alpha \cos\delta$ and $\delta$), three partial indices are defined, as shown in Table 1. The thresholds are set after the distributions of Fig. 3. The partial stability indices range from 1 (most stable) through 3 (least stable). A rejection value (10) is associated to very large drifts or standard deviations. Given the length of the available time series (up to 13 years), one could consider the Allan standard deviation for sampling times longer than one year (e.g. two or four years). The one-year interval is preferred because its estimation is expected to be more robust than for longer time spans.

  \begin{figure}
\par\includegraphics[width=88mm,clip]{MS3523f3.eps} %
\end{figure} Figure 3: Distributions of the partial stability criteria for the well observed sources over 1989.5-2002.4. The thresholds and corresponding partial indices listed in Table 1 are shown.

The partial stability criteria derived by applying the thresholds of Table 1 are then combined in five different ways, each one representing a different balance in the roles of the standard deviations and the drifts. Fifty sources were found to have apparent drifts larger than 50 $\mu $as/year. With at least one partial criterium equal to the rejection value (10), they are excluded a priori in the five options.

The partial indices combinations are as follows.

(a) Usual standard deviation only.
(b) Allan standard deviation only.
(c) Normalized velocity only.
(d) Usual standard deviation and normalized velocity.
(e) Allan standard deviation and normalized velocity.

The global stability index is then defined as the average of the partial indices for $\alpha \cos\delta$ and $\delta$, i.e. two values per source in cases (a), (b) and (c) and four values per source in cases (d) and (e). The stable sources are those which get a stablity index $\leq$2.5.

Combination (a) takes into account the statistical scatter of yearly coordinates, paying no attention to the fact that they belong to a time series. Combination (b) takes this aspect into account in a statistical way, while combination (c) takes it into account in a deterministic way, by modelling an assumed physical phenomenon. Combinations (d) and (e) mix the statistical and deterministic approaches.


 

 
Table 1: Partial stability criteria. The values range from 1 (best) through 3 (worse), with a rejection value of 10.
Statistics Threshold Partial index
Standard deviation (Stdv)
  Stdv $\leq$ 150 $\mu $as 1
  150 $\mu $as $\leq$ Stdv $\leq$ 300 $\mu $as 2
  300 $\mu $as $\leq$ Stdv $\leq$ 450 $\mu $as 3
  Stdv $\geq$ 450 $\mu $as 10
Allan Standard deviation (AlSd)
  AlSd $\leq$ 100 $\mu $as 1
  100 $\mu $as $\leq$ AlSd $\leq$ 200 $\mu $as 2
  200 $\mu $as $\leq$ AlSd $\leq$ 300 $\mu $as 3
  AlSd $\geq$ 300 $\mu $as 10
|Drift| (Vel)
  Vel $\leq$ 10 $\mu $as/year 1
  Vel $\geq$ 50 $\mu $as/year 10
|Normalized drift| (Nvl)
  Nvl $\leq$ 1 1
  1 $\leq$ Nvl $\leq$ 3 2
  Nvl $\geq$ 3 3


4 Testing the source selections

Out of the 362 preselected sources the investigated stability schemes produce between 186 and 208 stable sources, numbers to be compared to the 212 defining sources in the ICRF. To test their efficiency with respect to the maintenance of the axes of the celestial reference frame that they materialize, we consider the 13 yearly differential reference frames (1990.0-2002.0) that are formed by the set of stable sources observed in each year. The yearly differential rotation angles A1(y), A2(y), A3(y) around the axes of the equatorial coordinate system for year y are then computed for the 13 years. As the time series of yearly coordinates for each source are referred to the source global average ones, the rotation angles are not affected by the discrepancies between the particular realizations of the no-net-rotation condition attached to the three data treatments that produced the original data used in this work.

Table 2 lists efficiency estimates for the five stability schemes and for the ICRF defining sources. These estimates are the usual standard deviation that characterizes the scattering of the sets of rotation angles, and their Allan standard deviations for one-year and four-year sampling times, that characterize their stability in time. Note that if the time series of the rotation angles have white noise, the four-year Allan standard deviation will be equal to half (square root of one fourth in sampling time) the one-year one. In the case of flicker noise, both values will be equal.

The mixed schemes (d) and (e) keep more stable sources than the single-criterion ones, and yet they insure smaller scattering and better stability. Scheme (e), that takes into account the time series aspect of the data, has slightly better performances that scheme (d), with 5% less sources. As an example, source 2145+067, which shows an abrupt change of coordinates (-0.5 mas from 1998.0 to 1999.0) in a context of moderate drift (22 $\mu $as/year), is detected as unstable only by the Allan standard deviation.

The estimated efficiency of the ICRF defining sources is worse than that of selection (e) by nearly a factor of three for the one-year estimates and a factor of five in the longer term. The time series of the yearly rotation angles estimated on the basis of the defining sources have flicker noise at the level of 28 $\mu $as. The type of noise of those based on the stable sources (e) is closer to white noise.

5 Discussion

Table 6 (only available in the electronic version of the paper) gives details of the implementation of the selection scheme: number of sessions in which the source was observed, number of yearly points, one-year Allan standard deviation and drift, and four different stability indices. Note that in this table any stability index value larger than 4 is set to this value. For reference, the tables reproduces the values of the source redshifts and fluxes available at the IERS Celestial Reference System Product Center (IERS 2002). The stability indices are the following ones.

1.
The ICRF source status: d = defining, c = candidate, o = other, n = not available in ICRF Ext-1.
2.
The source structure index, when available in ICRF-Ext.1. This index (Fey & Charlot 2000) qualifies the level of position disturbance expected as a result of the the source structure (1 for the least disturbed, 4 for the most disturbed)
3.
The stability criterion derived in this paper; values 1 and 2 correspond to stable sources, 3 to unstable, and 4 to highly unstable or drifting. The stability indices are rounded off.
4.
The same stability criterion as above, but keeping only yearly averages based on at least twelve observations (instead of three).
When imposing a minimum number of twelve observations in the yearly averages instead of three, the difference in stability estimates are as follows. The source names listed are the 8-character IERS names. The alternate given are those used in the IVS operation. However, most sources have a number of other usual alternate names, the list of which can be found on an ftp site (IERS 2002) or obtained interactively at URL http://hpiers.obspm/fr/icrs-pc/icrf/srcform.html.


 

 
Table 2: Efficiency estimates for the tested stability schemes.
Source Nb. of Std Allan Std dev.
selection sources dev. 1 year 4 years
scheme kept $\mu $as $\mu $as $\mu $as

(a)
Stdv 195 11.5 10.1 8.7
(b) AlSd 186 14.1 8.8 8.9
(c) Nvl 192 11.3 9.6 5.2

(d)
Stdv+Nvl 208 11.3 9.8 6.7
(e) AlSd+Nvl 199 10.8 9.4 5.9

ICRF Defining
212 25.6 26.0 27.6


Table 3 shows the distribution of the type of noise for the stable and unstable sources as qualified by scheme (e). Sources with white noise are the most frequent globally. They are roughly equally distributed in the stable and unstable sources, as are the less frequent flicker noise sources. The sources with random walk noise are quite few, in particular among the stable sources. Note that these estimations are based on too short time series (13 values at most) to guarantee their robustness. Taking into account the type of noise may be considered for further improvement of the qualifying scheme, when longer time series become available. Table 4 lists the eight stable sources with random walk noise in either right ascension or in declination, i.e. for which the slopes of the Allan graph are close to +1. With the exception of 0119+041 and 2128-123, their Allan standard deviation for a four-year sampling time is small enough to deserve a partial stability index of 2.


 

 
Table 3: Type of noise for the stable and unstable sources as qualified by scheme (e), expressed as the percentage of the types of noise in both categories.
Type Stable sources Unst. sources
of noise RA Dec RA Dec

White
56% 69% 55% 60%
Flicker 40% 30% 38% 32%
Random walk 4% 1% 7% 8%



 

 
Table 4: Stable sources with random walk noise.The table gives the source stability index, the slope of the Allan variance graph and the Allan standard deviation for a four-year sampling time.
    RA cos($\delta$) Declination
Source Stb Slope 4-yr AlSd Slope 4-yr AlSd
  ind   $\mu $as   $\mu $as

0119+041
2 0.8 $\pm$ 0.2 350    
0133+476 2     0.7 $\pm$ 0.2 103
0229+131 2 1.1 $\pm$ 0.1 236    
0234+285 2 1.1 $\pm$ 0.4 95    
0552+398 2 0.7 $\pm$ 0.1 199    
0919-260 1 1.1 $\pm$ 0.1 131    
1611+343 2     0.6 $\pm$ 0.1 273
2128-123 2 1.4 $\pm$ 0.2 615    



 

 
Table 5: Stability index and ICRF source qualifiers: number of sources.
Stab. Source status Structure index
index Def. Can. Oth. 1 2 3-4
1 33 26 15 46 11 7
2 48 42 34 76 26 6
3 2 1 4 6 2 0
4 58 61 34 70 26 13



  \begin{figure}
\par\includegraphics[width=88mm,clip]{MS3523f4.eps} %
\end{figure} Figure 4: Partial stability criteria and ICRF source classes: defining (stars), candidate (diamonds) and other (circles). The lower left rectangle includes the sources selected as stable.

Figure 4 shows the relationship of the ICRF categories with the two components of the source stability index derived in this study for the 312 well observed sources with apparent drifts smaller than 50 $\mu $as/year over 1989.5-2002.4. The graphs give the positions of the defining, candidate and other sources as a function of both the one-year Allan standard deviation and the normalized drift. Although a number of defining sources fall in the lower-left zone which correspond to small partial stability indices, some of them are clearly detected as unstable. The candidate sources are globally in the same situation. Conversely, a number of "other'' sources, i.e. considered as having questionable stability in the ICRF work, are detected as stable. Compared to the ICRF selection, the proposed scheme rescues a number of sources that are in fact efficient for maintaining the ICRF axes directions.

Table 5 gives the relationship of the global stability index with two ICRF qualifiers: the source status (defining/candidate/other) and structure index. Again, there is no particular correlation of the instantaneous structure indices with the time stability ones. This finding is of interest in the context of studying the dynamics of the quasars activity. Similarly, there is no clear relationship of the source total fluxes in the X and S bands with their direction time variability. A possible relationship with the flux variability remains to be investigated.

When compared to the current ICRF defining sources, the selection scheme developed in this study achieves improved time stability of yearly reference frames, which implies improved internal consistency. This has consequences not only in astrometric applications, but it may also have bearings in the geophysical interpretation of the Earth's orientation in inertial space. As an example, Dehant et al. (2003) have shown that source instabilities perturb nutation determinations at the level of tens of $\mu $as, comparable to that of the excitation of the Earth's rotation axis orientation by diurnal oscillations in the atmosphere.

Finally, we recommend that the set of selected stable sources be considered on the one hand in any future improvement of the International Celestial Reference Frame, and on the other hand in the scheduling of repeated VLBI sessions for Earth rotation, geodesy and astrometry.

Acknowledgements
The data analysis in this study is entirely based on the time series of coordinates of 707 radio source derived by Alan Fey (USNO) using 3.6 millions of observations accumulated in various US and international programs since 1979.

References

  
6 Online Material


 

 
Table 6: Stability criteria for 362 well observed extragalactic sources, 1989.5-2002.4. The redshift and the total flux at 6 cm, 11/15 cm are given when available. "AlSd'' is the Allan standard deviation for a one-year sampling time. Stability criterion 1 is the ICRF one (d = defining, c = candidate, o = other). Stability criterion 3 is the one derived in this paper; values 1 and 2 correspond to stable sources, 3 to unstable, and 4 to highly unstable or drifting. Stability criteria 2 and 4: see explanation in the text
        Flux (Jansky)     RA $\cos(\delta)$ Declination Stability
No. Source Alter. Redsh. 6 11 15 Number AlSd Drift AlSd Drift criteria
        cm cm cm sess pts $\mu $as $\mu $as/year $\mu $as $\mu $as/year 1 2 3 4
1 0003+380   .23 .5   .6 12 8 32 -2 $\pm$ 20 15 -2 $\pm$ 11 d 1 1 1
2 0003-066   .35 1.6   1.7 492 12 110 -9 $\pm$ 8 177 30 $\pm$ 24 c 1 2 2
3 0007+171   1.60 1.2 .9   14 7 44 -66 $\pm$ 15 41 7 $\pm$ 31 d 1 4  
4 0008-264   1.09 .8   .6 12 9 19 -50 $\pm$ 13 64 101 $\pm$ 39 c   4  
5 0013-005   1.57 .8 .8   54 11 597 15 $\pm$ 4 70 4 $\pm$ 10 c 1 4 4
6 0014+813   3.39 .6   1.0 449 11 96 -7 $\pm$ 4 207 54 $\pm$ 11 d 1 4 4
7 0016+731   1.78 1.6   1.5 425 12 169 -26 $\pm$ 6 134 -15 $\pm$ 6 o 1 2 2
8 0019+058     .5 .5   27 9 26 -35 $\pm$ 6 112 -154 $\pm$ 32 o 1 4  
9 0026+346   .52     1.8 12 5 98 -393 $\pm$ 52 10 38 $\pm$ 26 o 4 4  
10 0048-097     1.9   1.3 1058 13 83 -5 $\pm$ 3 104 -7 $\pm$ 7 o 1 1 1
11 0056-001   .72 1.4   2.2 12 8 136 -262 $\pm$ 51 94 194 $\pm$ 90 c 3 4  
12 0059+581           932 11 158 2 $\pm$ 5 197 -26 $\pm$ 4 o 1 2 2
13 0104-408   .58 .9 .6   499 13 81 -4 $\pm$ 12 71 23 $\pm$ 13 o   1 1
14 0106+013   2.11 3.7   3.9 1280 13 69 6 $\pm$ 5 93 1 $\pm$ 9 o 1 1 1
15 0109+224     .8 .4   14 9 72 24 $\pm$ 25 30 13 $\pm$ 13 d 1 1 1
16 0111+021   .05       167 12 39 -16 $\pm$ 9 39 -3 $\pm$ 13 c 1 1 1
17 0112-017   1.37 1.2 1.4   49 10 192 68 $\pm$117 79 58 $\pm$ 40 c 1 4 4
18 0113-118   .67 1.9 1.8   27 9 179 -31 $\pm$ 93 117 -313 $\pm$ 49 o 2 4 4
19 0119+041   .64 1.2   .9 1427 13 192 2 $\pm$ 11 161 -1 $\pm$ 7 c 1 2 2
20 0119+115   .57 1.0   1.8 387 11 45 4 $\pm$ 4 179 -34 $\pm$ 14 c 1 2 2
21 0133+476   .86 3.3   2.1 500 13 136 -14 $\pm$ 5 68 -12 $\pm$ 4 d 1 2 2
22 0134+329 3C48 .37 5.4 9.0   11 5 88 56 $\pm$159 85 -299 $\pm$189 o 4 4  
23 0146+056   2.35 1.2 .7   54 10 28 32 $\pm$ 15 89 63 $\pm$ 28 c 1 4 4
24 0149+218   1.32 1.1   1.4 43 9 107 -10 $\pm$ 13 104 30 $\pm$ 22 d 2 2 2
25 0159+723     .3 .3   19 7 37 -7 $\pm$ 26 84 -16 $\pm$ 41 d 1 1 1
26 0201+113   3.61 1.2   1.3 360 13 91 21 $\pm$ 7 131 -22 $\pm$ 16 c 1 2 2
27 0202+149   .41 3.1   3.2 516 13 174 -9 $\pm$ 7 228 49 $\pm$ 9 c 2 2 2
28 0202+319   1.47 1.0   1.6 40 11 55 -19 $\pm$ 10 41 -4 $\pm$ 11 d 2 1 1
29 0208-512   1.00 3.2 3.6   274 13 140 3 $\pm$ 17 127 -58 $\pm$ 21 o   4 4
30 0212+735   2.37 2.2   2.3 1264 12 196 36 $\pm$ 8 127 -27 $\pm$ 6 o 2 3 3
31 0215+015   1.72 .4 .4   23 9 173 34 $\pm$ 36 87 11 $\pm$ 18 d 1 1 1
32 0221+067   .51 1.0   1.4 45 9 85 20 $\pm$ 14 29 -44 $\pm$ 16 c 2 2 2
33 0224+671 4C67.05       1.2 40 7 74 20 $\pm$ 32 90 28 $\pm$ 37 d 1 1 1
34 0229+131   2.07 1.0   2.0 1946 13 105 -23 $\pm$ 3 125 -11 $\pm$ 4 c 1 2 2
35 0230-790   1.07 .8 .6   11 7 70 10 $\pm$170 43 -129 $\pm$ 91 d   4  
36 0234+285   1.21 2.8 1.2   1085 12 49 11 $\pm$ 1 123 -5 $\pm$ 3 c 2 2 2
37 0235+164   .94 2.8   2.0 442 13 103 1 $\pm$ 4 121 -14 $\pm$ 5 d 1 2 2
38 0237+040   .98 .8   .8 22 8 56 8 $\pm$ 18 118 140 $\pm$ 45 c 1 4 4
39 0237-027   1.12 .6 .4   14 8 174 137 $\pm$102 104 -209 $\pm$ 65 c 1 4 4
40 0237-233   2.22 3.2 5.3   13 7 52 -20 $\pm$ 62 78 22 $\pm$140 o 3 1  
41 0238-084 NGC1052 .00 .9 .6   275 10 123 -87 $\pm$ 22 138 -38 $\pm$ 26 o 2 4 4
42 0239+108         1.8 83 12 78 28 $\pm$ 11 44 -62 $\pm$ 13 d 2 4 4
43 0248+430   1.31 1.2 1.0   13 7 84 -47 $\pm$ 25 115 122 $\pm$ 40 d 2 4 4
44 0256+075   .89 1.0   .7 38 8 95 26 $\pm$ 32 72 21 $\pm$ 55 d 1 1  
45 0300+470     2.2 1.8   716 12 166 -15 $\pm$ 9 296 36 $\pm$ 18 o 1 2 4
46 0302-623           18 6 81 59 $\pm$ 58 51 -17 $\pm$ 60 d   4 4
47 0306+102   .86 .7   1.3 30 9 96 40 $\pm$ 23 79 -37 $\pm$ 22 d 1 2 2
48 0308-611           80 8 133 17 $\pm$ 45 73 30 $\pm$ 26 d   2 2
49 0309+411   .14 .5   .6 12 6 13 -12 $\pm$ 8 69 22 $\pm$ 5 d 2 2  
50 0317+188           30 6 32 16 $\pm$ 15 56 -27 $\pm$ 41 c 1 1  
51 0319+121   2.67 1.5   1.4 20 10 35 -5 $\pm$ 20 51 40 $\pm$ 42 o 3 1 1
52 0332-403   1.45 2.6 1.9   11 7 129 -147 $\pm$ 30 212 -426 $\pm$ 55 o   4  
53 0333+321 NRAO140 1.26 2.0   2.3 80 10 72 -11 $\pm$ 13 67 -11 $\pm$ 10 o 3 1 1
54 0336-019 CTA26 .85 2.6   2.7 726 13 160 16 $\pm$ 8 279 -25 $\pm$ 12 c 1 2 2
55 0338-214   .05 .9 .8   29 7 101 -124 $\pm$ 77 126 -87 $\pm$ 71 o   4 4
56 0341+158           22 7 50 -39 $\pm$ 6 104 110 $\pm$ 82 c 1 4  
57 0342+147           32 10 59 -50 $\pm$ 11 176 -69 $\pm$ 37 d 1 4 4
58 0355+508 NRAO150       6.8 470 9 43 6 $\pm$ 16 88 -20 $\pm$ 28 o 3 1 1
59 0400+258   2.11 1.8   1.4 36 9 120 26 $\pm$ 15 85 46 $\pm$ 16 d 2 2 2
60 0402-362   1.42 1.9 1.0   344 13 38 -14 $\pm$ 9 57 -18 $\pm$ 16 o   2 2
61 0403-132   .57 2.9   4.0 11 6 23 -49 $\pm$ 6 49 88 $\pm$ 29 o 1 4  
62 0405-385   1.28 1.1   1.0 73 9 19 13 $\pm$ 26 44 97 $\pm$ 23 c   4  
63 0406+121   1.02 1.6 1.2   32 9 75 -29 $\pm$ 40 260 20 $\pm$156 d 1 2 2
64 0406-127   1.56 .5 .6   16 7 79 -8 $\pm$ 3 159 69 $\pm$ 33 c 1 4  
65 0414-189   1.54 .8   1.0 11 6 125 113 $\pm$ 18 19 -43 $\pm$ 5 d 1 4  
66 0420+417         1.7 19 8 63 -36 $\pm$ 22 39 23 $\pm$ 24 c 2 1  
67 0420-014   .92 1.6   1.0 1247 11 228 -10 $\pm$ 12 222 -45 $\pm$ 12 o 1 3 3
68 0422+004     1.6   .8 18 8 48 -15 $\pm$ 26 98 61 $\pm$ 58 d 1 4 4
69 0422-380   .78 .8 .5   15 8 28 -29 $\pm$ 20 32 89 $\pm$ 28 d   4  
70 0425+048           16 7 34 52 $\pm$ 59 24 174 $\pm$ 38 c 3 4  
71 0430+052 3C120 .03 5.1   6.4 97 9 183 -50 $\pm$ 39 50 -18 $\pm$ 10 o 3 4 4
72 0430+289     .5 .4   33 5 27 30 $\pm$ 28 71 -4 $\pm$ 29 n   1 1
73 0434-188   2.70 1.1   1.3 92 12 82 56 $\pm$ 14 99 17 $\pm$ 37 o 1 4 4
74 0440+345           30 10 41 15 $\pm$ 5 148 72 $\pm$ 19 c 1 4 4
75 0440-003 NRAO190 .84 2.4 3.5   18 7 40 -61 $\pm$ 15 40 -95 $\pm$ 37 d 1 4  
76 0451-282   2.56 2.2   2.3 11 7 78 -48 $\pm$ 63 124 104 $\pm$106 c   4  
77 0454+844   $\ge$1.34 1.4   1.3 58 11 139 -14 $\pm$ 13 116 -25 $\pm$ 17 d 1 2 2
78 0454-234   1.00 1.9 1.8   1600 13 136 7 $\pm$ 7 124 3 $\pm$ 6 o 1 2 2
79 0454-810   .44 1.4 1.2   20 7 65 -218 $\pm$ 85 29 113 $\pm$ 26 d   4  
80 0457+024   2.38 1.2   1.3 59 11 57 29 $\pm$ 19 66 -1 $\pm$ 30 d 1 1 1
81 0458-020   2.29 1.6   2.0 1256 13 211 -16 $\pm$ 7 200 -21 $\pm$ 7 c 1 3 3
82 0500+019   .58 2.0   2.0 16 9 223 -54 $\pm$ 16 317 246 $\pm$ 62 o 3 4 4
83 0502+049   .95 1.0   .6 11 6 4 9 $\pm$ 6 8 -9 $\pm$ 15 d 2 1  
84 0507+179   .42 .8   .7 42 12 120 -35 $\pm$ 22 95 -6 $\pm$ 23 d 2 2 2
85 0521-365   .05 8.9   11.5 90 11 488 261 $\pm$ 82 342 -446 $\pm$ 87 d   4  
86 0528+134   2.07 4.4 2.7   2546 13 469 -7 $\pm$ 8 198 4 $\pm$ 4 c 1 4 4
87 0528-250   2.77 .8 1.3   16 8 56 -18 $\pm$ 31 120 88 $\pm$102 o   4  
88 0530-727           55 7 43 -13 $\pm$ 29 76 32 $\pm$ 47 d   1 1
89 0536+145           33 7 96 -18 $\pm$ 12 58 -74 $\pm$ 20 o 1 4 4
90 0537-286   3.10 1.2   1.0 19 9 90 74 $\pm$ 35 52 -59 $\pm$ 19 d   4  
91 0537-441   .90 4.0 3.8   360 13 109 39 $\pm$ 8 82 24 $\pm$ 11 o 1 2 2
92 0539-057   .84 1.5 1.3   12 8 50 63 $\pm$ 41 39 32 $\pm$ 88 d 1 4  
93 0544+273           34 7 70 -17 $\pm$ 21 163 -101 $\pm$ 39 d 1 4 4
94 0552+398   2.36 5.4   3.4 3039 13 129 -8 $\pm$ 1 148 -5 $\pm$ 2 c 1 2 2
95 0554+242           22 5 42 -112 $\pm$ 36 173 -99 $\pm$ 83 n   4 4
96 0556+238           245 12 95 -35 $\pm$ 12 131 -75 $\pm$ 17 d 1 4  
97 0600+177           11 6 100 -22 $\pm$ 39 98 -34 $\pm$ 42 c 1 1  
98 0602+673   1.97 1.1 .8   13 7 85 38 $\pm$ 12 66 -48 $\pm$ 6 c   2 2
99 0605-085   .87 2.7 3.0   27 9 42 -16 $\pm$ 17 57 -25 $\pm$ 35 c 1 1 1
100 0607-157   .32 3.1   1.0 22 9 109 -36 $\pm$ 26 63 19 $\pm$ 14 c 2 2 4
101 0615+820   .71 1.0   1.3 30 8 51 -9 $\pm$ 25 60 35 $\pm$ 18 d 1 1 1
102 0636+680   3.18 .5 .3   34 9 30 15 $\pm$ 7 64 -17 $\pm$ 8 d 1 2 2
103 0637-752   .65 6.2 4.5   277 13 247 -23 $\pm$ 21 109 16 $\pm$ 10 d   2 2
104 0642+449   3.41 .8   1.2 464 12 113 2 $\pm$ 6 69 -1 $\pm$ 3 d 1 1 1
105 0646-306   .46 1.1   .9 11 6 39 170 $\pm$ 42 41 172 $\pm$ 86 c 2 4  
106 0648-165           17 7 109 -30 $\pm$ 35 115 192 $\pm$ 53 d 1 4 4
107 0650+371   1.98 1.0   1.0 30 7 192 -249 $\pm$ 45 109 -202 $\pm$ 58 c 1 4 4
108 0657+172           114 12 88 -14 $\pm$ 7 85 -6 $\pm$ 7 c 1 1 1
109 0707+476   1.29 1.0   .8 13 7 150 -26 $\pm$ 8 165 45 $\pm$ 26 d 1 2 2
110 0716+714     1.1   .7 94 10 38 -12 $\pm$ 7 108 -33 $\pm$ 15 d 1 2 2
111 0718+792 0718+793       1.0 476 10 78 23 $\pm$ 5 57 1 $\pm$ 4 d 1 2 2
112 0723-008   .13 2.3   2.1 27 8 163 45 $\pm$ 77 173 -94 $\pm$ 77 d 2 4 4
113 0727-115           2101 13 159 12 $\pm$ 4 165 16 $\pm$ 7 o 1 2 2
114 0735+178   $\ge$.42 2.0   2.0 486 12 377 -40 $\pm$ 25 180 -10 $\pm$ 12 o 1 4 4
115 0736+017   .19 1.9   2.9 43 11 234 4 $\pm$ 13 35 18 $\pm$ 13 c 3 2 2
116 0738+313   .63 2.5   1.9 22 9 144 -6 $\pm$ 2 80 -15 $\pm$ 2 d 1 2 2
117 0742+103         3.9 301 12 126 39 $\pm$ 13 129 -52 $\pm$ 13 o 1 4 4
118 0743+259         .6 18 9 176 -14 $\pm$ 71 122 122 $\pm$ 41 d 1 4  
119 0743-006   .99 1.3 1.0   24 9 116 -95 $\pm$ 31 289 -412 $\pm$ 45 o 1 4  
120 0745+241   .41 1.3 .7   111 10 57 -20 $\pm$ 9 47 -32 $\pm$ 6 d 2 2 2
121 0748+126   .89 2.2   2.0 20 7 24 8 $\pm$ 11 74 22 $\pm$ 38 c 2 1 1
122 0749+540   $\ge$.20 .6 .7   376 12 141 -27 $\pm$ 4 96 -4 $\pm$ 3 d 1 2 2
123 0754+100   .28 1.5 1.0   20 8 27 -28 $\pm$ 14 47 -11 $\pm$ 21 d 1 1 1
124 0804+499   1.43 2.1   1.3 768 13 101 6 $\pm$ 3 101 -5 $\pm$ 3 d 1 2 2
125 0805+410   1.42 .8   .7 240 11 67 -5 $\pm$ 7 53 4 $\pm$ 5 d 1 1 1
126 0808+019     .7   .4 28 8 199 86 $\pm$ 25 247 -228 $\pm$ 37 c 1 4 4
127 0814+425   .26 1.7   1.6 116 11 165 -82 $\pm$ 11 75 -11 $\pm$ 6 c 1 4 4
128 0818-128     .9   .9 18 7 86 29 $\pm$ 24 35 -11 $\pm$ 20 d 1 1  
129 0820+560   1.42 1.2   1.7 53 11 29 52 $\pm$ 4 27 4 $\pm$ 3 d 1 4 4
130 0821+394   1.22 1.0   1.9 14 8 19 -8 $\pm$ 6 41 -39 $\pm$ 14 d 2 1 1
131 0821+621   .54 .6 .3   12 6 218 -261 $\pm$ 35 90 38 $\pm$ 20 c   4 4
132 0823+033   .51 1.4   1.4 785 13 161 -21 $\pm$ 6 190 -17 $\pm$ 13 c 1 2 2
133 0826-373           16 9 53 -77 $\pm$ 13 24 -2 $\pm$ 22 d   4  
134 0827+243   .94 .9   1.3 62 10 108 -8 $\pm$ 13 162 47 $\pm$ 17 c 2 2 2
135 0828+493   .55 1.0   .5 14 8 16 0 $\pm$ 11 62 33 $\pm$ 44 d 1 1 1
136 0829+046   .18 .7   .7 14 7 123 -93 $\pm$ 34 133 111 $\pm$ 61 d 2 4 4
137 0839+187   1.27 1.2   2.2 21 10 140 52 $\pm$ 21 363 218 $\pm$ 85 d 3 4 4
138 0851+202 OJ287 .31 2.6 3.4   2756 13 224 9 $\pm$ 4 121 5 $\pm$ 3 c 1 2 2
139 0859-140   1.34 2.3   2.9 18 7 57 46 $\pm$ 31 62 36 $\pm$ 26 c 3 2 4
140 0906+015   1.02 .9   .8 25 9 55 -18 $\pm$ 39 58 -53 $\pm$ 79 c 2 4 4
141 0917+624   1.45 1.2   1.6 123 10 132 -34 $\pm$ 13 129 31 $\pm$ 11 d 1 2 2
142 0919-260   2.30 2.4   1.2 336 13 62 3 $\pm$ 22 137 21 $\pm$ 31 o 2 1 1
143 0920+390           44 7 95 -91 $\pm$ 16 63 -13 $\pm$ 21 c   4 4
144 0920-397   .59 1.5   2.1 88 12 62 -17 $\pm$ 15 140 -227 $\pm$ 59 c   4 4
145 0923+392 4C39.25 .70 7.6   4.2 2756 13 296 52 $\pm$ 3 153 -11 $\pm$ 2 o 1 4 4
146 0925-203   .35 .7 .8   17 6 47 20 $\pm$ 31 44 29 $\pm$ 40 c   1  
147 0945+408   1.25 1.8   1.7 14 9 64 -17 $\pm$ 16 66 -14 $\pm$ 11 d 2 2 1
148 0951+693 M81   .1   .5 65 9 127 3 $\pm$ 25 164 -10 $\pm$ 25 o   2 2
149 0952+179   1.48 .7   1.0 33 10 64 -38 $\pm$ 12 74 39 $\pm$ 23 d 3 2 2
150 0953+254 OK290 .71 1.8   1.3 530 13 284 38 $\pm$ 18 219 49 $\pm$ 15 o 1 3 3
151 0954+658   .37 1.5   .9 247 12 90 1 $\pm$ 8 113 -31 $\pm$ 17 d 1 2 2
152 0955+326   .53 .7   .7 13 8 70 0 $\pm$ 4 126 9 $\pm$ 6 d 2 1 1
153 0955+476   1.87 1.0   1.1 1049 11 329 -33 $\pm$ 4 119 2 $\pm$ 2 d 1 4 4
154 1004+141   2.71 .7   .8 262 13 145 16 $\pm$ 23 98 18 $\pm$ 13 o 2 2 2
155 1012+232   .56 1.1 .7   13 7 27 27 $\pm$ 19 53 13 $\pm$ 30 d 1 1 1
156 1014+615   2.80       19 7 225 -128 $\pm$ 47 50 -43 $\pm$ 8 c   4 4
157 1020+400   1.25 .9   1.2 15 10 219 -10 $\pm$ 2 35 -27 $\pm$ 6 d 1 3 2
158 1022+194   .83 .6   1.0 22 6 43 -12 $\pm$ 13 172 94 $\pm$ 61 c 2 4  
159 1030+415   1.12 1.1   .8 15 6 58 -122 $\pm$ 28 29 -53 $\pm$ 20 d 2 4  
160 1032-199   2.20 1.0 1.1   11 8 146 305 $\pm$ 42 196 -222 $\pm$ 76 d   4  
161 1034-293   .31 1.5   1.3 1081 13 113 -9 $\pm$ 7 138 8 $\pm$ 11 o 1 2 2
162 1038+064   1.26 1.3   1.6 48 11 74 -58 $\pm$ 17 119 125 $\pm$ 51 d 1 4 4
163 1038+528 1038+52A .68 .7 .4   162 10 59 -13 $\pm$ 10 168 39 $\pm$ 24 d   2 2
164 1039+811   1.26 1.1 .9   37 11 41 4 $\pm$ 10 53 -3 $\pm$ 14 d 1 1 1
165 1044+719   1.15 .7   1.0 508 12 240 -19 $\pm$ 12 204 5 $\pm$ 12 c 1 2 2
166 1045-188   .60 1.1 .9   12 7 5 -13 $\pm$ 2 18 -34 $\pm$ 4 o 1 2  
167 1053+704   2.49 .7   .6 27 9 111 -1 $\pm$ 21 34 -20 $\pm$ 3 c 1 2 2
168 1053+815   .71 .8   .6 179 12 75 -6 $\pm$ 5 114 8 $\pm$ 6 d 1 1 1
169 1055+018   .89 3.4   2.9 258 12 125 -3 $\pm$ 11 95 13 $\pm$ 13 o 2 2 2
170 1057-797           249 13 120 -11 $\pm$ 11 162 -24 $\pm$ 12 d   2 2
171 1101+384   .03 .7   1.0 209 9 138 -36 $\pm$ 11 78 5 $\pm$ 11 c 1 2 2
172 1101-536           33 8 63 77 $\pm$ 8 136 139 $\pm$ 47 c   4 4
173 1104-445   1.60 2.0 1.8   203 12 122 -119 $\pm$ 19 87 70 $\pm$ 27 o   4  
174 1111+149   .87 .5 .6   20 9 35 -20 $\pm$ 21 50 46 $\pm$ 30 d 1 1 1
175 1123+264   2.34 .8   .7 129 9 71 -9 $\pm$ 24 52 6 $\pm$ 13 o 1 1 1
176 1124-186   1.05 1.6   .6 405 12 64 5 $\pm$ 7 52 -8 $\pm$ 7 c 1 1 1
177 1127-145   1.19 7.3 6.4   28 9 200 -84 $\pm$ 85 43 45 $\pm$ 27 c 2 4 4
178 1128+385   1.73 .8   .9 707 12 85 -13 $\pm$ 3 138 6 $\pm$ 6 d 1 2 2
179 1130+009         .3 28 12 120 43 $\pm$ 67 88 -11 $\pm$ 73 d 1 1  
180 1144+402   1.09 1.0   .9 120 12 88 5 $\pm$ 7 129 -40 $\pm$ 13 o 1 2 2
181 1144-379   1.05 2.2 1.1   393 13 65 1 $\pm$ 8 85 50 $\pm$ 12 c   4 2
182 1145-071   1.34 1.2   1.0 114 10 64 -27 $\pm$ 11 121 -2 $\pm$ 19 c 1 2 2
183 1148-001   1.98 1.9   2.5 21 9 86 -103 $\pm$ 50 74 -119 $\pm$ 52 c 3 4  
184 1150+812   1.25 1.2   1.2 60 10 75 13 $\pm$ 8 110 20 $\pm$ 9 d 2 2  
185 1156+295   .73 1.5   1.3 589 13 125 -16 $\pm$ 4 205 -2 $\pm$ 7 c 2 2 2
186 1213+350   .86 1.0   1.2 16 8 44 -58 $\pm$ 22 21 6 $\pm$ 13 d 1 4 4
187 1213-172         1.2 18 8 160 36 $\pm$ 10 347 -93 $\pm$ 44 c 1 4  
188 1216+487   1.08 1.1   .7 15 9 28 -1 $\pm$ 21 42 -2 $\pm$ 23 d 1 1 1
189 1219+044   .96 1.4   .6 836 11 32 2 $\pm$ 2 157 -10 $\pm$ 9 d 1 1 1
190 1219+285   .10 .7   1.5 18 9 84 15 $\pm$ 37 54 -24 $\pm$ 24 c 2 1  
191 1221+809     .5 .4   19 10 62 -36 $\pm$ 9 35 -18 $\pm$ 4 d 1 2 2
192 1222+037   .96 1.2   1.0 53 10 71 56 $\pm$ 21 56 -82 $\pm$ 27 c 2 4 4
193 1226+023 3C273B .16 43.4 41.4   1012 9 101 -227 $\pm$ 58 48 -137 $\pm$ 21 o   4  
194 1226+373   1.51 .9 .2   13 7 162 17 $\pm$ 46 180 -69 $\pm$ 62 d 1 4  
195 1228+126 3C274 .00 71.9     407 12 90 -10 $\pm$ 7 118 2 $\pm$ 9 c 3 1 1
196 1236+077   .40 .7   .6 16 8 58 -1 $\pm$ 40 108 157 $\pm$ 56 d 1 4 4
197 1237-101   .75 1.5   1.6 21 6 31 6 $\pm$ 22 104 129 $\pm$ 21 c   4  
198 1243-072   1.29 .9   .7 31 7 77 -83 $\pm$ 12 90 -39 $\pm$ 71 c 1 4  
199 1244-255   .64 2.3   1.4 76 10 125 2 $\pm$ 30 48 -44 $\pm$ 14 c   2 4
200 1251-713           18 7 53 -51 $\pm$ 43 73 -123 $\pm$ 51 d   4  
201 1252+119   .87 .7   1.8 35 7 37 70 $\pm$ 25 32 -5 $\pm$ 29 d 1 4 4
202 1253-055 3C279 .54 15.3   11.8 223 11 202 195 $\pm$ 32 152 -72 $\pm$ 33 o 2 4 4
203 1255-316   1.92 1.4   1.6 144 11 77 65 $\pm$ 24 69 122 $\pm$ 23 c   4 4
204 1257+145         2.9 14 8 123 -181 $\pm$ 80 100 148 $\pm$ 74 d 1 4  
205 1300+580           197 9 89 -12 $\pm$ 6 45 -1 $\pm$ 5 o 1 1 1
206 1302-102   .29 .8   1.0 48 11 95 83 $\pm$ 16 109 120 $\pm$ 44 c 1 4 4
207 1308+326   1.00 1.5 1.6   1314 13 233 -3 $\pm$ 10 232 17 $\pm$ 10 d 1 2 2
208 1308+328   1.65 1.1     34 7 66 22 $\pm$ 17 127 72 $\pm$ 25 n   4 4
209 1313-333   1.21 1.1   1.2 177 11 35 -4 $\pm$ 10 132 -19 $\pm$ 50 c 1 1 1
210 1315+346 OP326 1.05 .3 .5   21 10 75 7 $\pm$ 10 53 -39 $\pm$ 17 c 1 1  
211 1334-127   .54 2.8   1.9 1670 13 183 -18 $\pm$ 6 108 -10 $\pm$ 6 o 1 2 2
212 1342+663   1.35 .8 .6   39 10 60 5 $\pm$ 13 84 -19 $\pm$ 17 d 1 1 1
213 1347+539   .98 1.0   .9 14 9 117 -117 $\pm$ 35 118 -32 $\pm$ 19 d 2 4  
214 1349-439   .05 .8 .5   21 9 27 -17 $\pm$ 42 30 33 $\pm$ 42 c   1  
215 1351-018   3.71 .8   .8 434 11 121 6 $\pm$ 8 111 34 $\pm$ 10 c 1 2 2
216 1354+195   .72 2.6   1.8 124 12 104 12 $\pm$ 12 107 16 $\pm$ 18 o 2 2 2
217 1354-152   1.89 .8   1.2 91 10 378 -8 $\pm$ 68 430 82 $\pm$116 c 1 4 4
218 1357+769           861 11 98 -1 $\pm$ 3 116 5 $\pm$ 2 c 1 1 1
219 1402+044   3.21 .7   .6 41 8 253 17 $\pm$ 46 201 -34 $\pm$ 71 c 1 2 2
220 1404+286 OQ208 .08 2.9   1.7 1156 12 39 2 $\pm$ 2 139 47 $\pm$ 5 o 1 2 2
221 1406-076   1.49 .8   1.3 31 10 32 -9 $\pm$ 12 33 31 $\pm$ 17 c 1 1  
222 1413+135   .25 1.2   .9 36 12 81 19 $\pm$ 12 59 36 $\pm$ 16 o 3 2 2
223 1418+546   .15 1.1   1.0 356 12 129 -7 $\pm$ 5 109 9 $\pm$ 4 d 2 2 2
224 1424-418   1.52 2.2   2.2 296 13 82 -23 $\pm$ 12 125 -8 $\pm$ 23 o   2 2
225 1435+638   2.07 .8   1.6 15 8 51 54 $\pm$ 23 40 -4 $\pm$ 34 d 3 4 4
226 1442+101 OQ172 3.54 1.1   2.0 30 9 156 31 $\pm$103 103 9 $\pm$ 62 d 3 2 2
227 1448+762   .90 .7   1.0 21 8 45 -72 $\pm$ 31 89 -41 $\pm$ 28 d 1 4 4
228 1451-375   .31 1.8   1.4 114 11 103 -34 $\pm$ 17 107 -22 $\pm$ 49 c   2 2
229 1451-400   1.81 .6 .7   27 7 133 -3 $\pm$ 57 78 24 $\pm$ 49 c   1 1
230 1458+718 3C309.1 .90 3.8   6.9 18 9 69 36 $\pm$ 18 132 -188 $\pm$ 33 o 3 4 4
231 1459+480         .5 12 7 20 25 $\pm$ 12 20 20 $\pm$ 17 d 1 2 2
232 1502+106   1.83 2.5   2.0 567 10 132 -25 $\pm$ 14 45 17 $\pm$ 3 o 1 2 2
233 1504-166   .88 2.8   2.2 29 6 90 16 $\pm$ 76 80 11 $\pm$ 55 c 1 1 1
234 1508+572   4.30 .3     51 7 80 -52 $\pm$ 15 109 -37 $\pm$ 22 c   4 4
235 1510-089   .36 4.4   3.1 315 11 166 -4 $\pm$ 13 127 -17 $\pm$ 12 o 1 2 2
236 1511-100   1.51 1.2   .9 19 8 210 -97 $\pm$ 31 90 -4 $\pm$ 57 c 1 4  
237 1514+197   1.07 .5   .5 12 8 37 -8 $\pm$ 5 62 28 $\pm$ 10 d 1 1  
238 1514-241   .05 1.9   1.9 215 10 96 -31 $\pm$ 14 69 6 $\pm$ 22 c   1 2
239 1519-273     1.8   1.0 183 11 112 -11 $\pm$ 10 110 -8 $\pm$ 11 c   2 2
240 1538+149   .61 2.0   1.5 35 8 133 -24 $\pm$ 38 165 23 $\pm$ 49 d 1 2 2
241 1546+027   .41 1.1   .8 41 11 96 22 $\pm$ 16 154 12 $\pm$ 57 c 1 2 2
242 1547+507   2.17 .7 .7   14 6 28 45 $\pm$ 18 28 31 $\pm$ 20 d 3 2 1
243 1548+056   1.42 2.2   2.3 216 11 83 -33 $\pm$ 12 104 125 $\pm$ 21 o 2 4 4
244 1557+032   3.89 .5 .5   27 6 174 -12 $\pm$ 43 355 35 $\pm$152 c   4 4
245 1600+335         2.7 16 6 213 21 $\pm$ 12 61 38 $\pm$ 12 d 1 2 2
246 1604-333         .6 20 8 48 56 $\pm$ 50 110 22 $\pm$ 71 d   4  
247 1606+106   1.23 1.4   1.0 1211 13 190 21 $\pm$ 4 195 1 $\pm$ 5 d 1 2 2
248 1610-771   1.71 5.6 3.8   260 13 155 36 $\pm$ 29 229 10 $\pm$ 28 o   2 2
249 1611+343   1.40 2.3 2.4   1055 13 119 -11 $\pm$ 2 182 14 $\pm$ 5 c 1 2 2
250 1614+051   3.22 .9   .6 117 10 72 15 $\pm$ 13 104 -25 $\pm$ 28 c 1 2 2
251 1622-253   .79 2.2 2.3   1246 13 89 -3 $\pm$ 5 82 -18 $\pm$ 7 o 1 1 1
252 1622-297   .81 1.9   2.2 41 9 72 18 $\pm$ 43 58 -22 $\pm$ 44 c   1 1
253 1624+416   2.55 1.6   1.5 31 10 78 7 $\pm$ 19 118 -7 $\pm$ 30 d 2 1 1
254 1633+382 1633+38 1.81 4.1   2.1 433 11 146 15 $\pm$ 12 128 5 $\pm$ 12 o 1 2 2
255 1637+574   .75 1.8   1.4 258 12 102 6 $\pm$ 10 123 17 $\pm$ 19 d 1 2 2
256 1638+398 NRAO512 1.67 1.2   1.1 814 12 169 -11 $\pm$ 8 115 23 $\pm$ 4 o 1 2 2
257 1641+399 3C345 .59 5.7   7.6 1087 10 335 85 $\pm$ 44 210 75 $\pm$ 9 o 1 4 4
258 1642+690   .75 1.4   1.7 146 11 86 4 $\pm$ 5 64 23 $\pm$ 5 d 2 2 2
259 1652+398 DA426 .03 1.3 1.5   207 11 57 -2 $\pm$ 6 89 34 $\pm$ 10 c 2 2 2
260 1655+077   .62 1.6   1.6 18 9 62 -23 $\pm$ 18 63 28 $\pm$ 38 c 3 1 1
261 1656+053   .88 1.4   1.6 45 9 1304 205 $\pm$ 45 294 22 $\pm$ 6 c 2 4 4
262 1657-261         1.1 30 10 39 43 $\pm$ 16 97 45 $\pm$106 c   1  
263 1705+018   2.58 .5 .5   42 9 48 15 $\pm$ 10 48 85 $\pm$ 16 d 1 4 4
264 1706-174           37 11 66 -49 $\pm$ 36 73 -52 $\pm$ 53 d 1 4  
265 1717+178     .9   1.0 15 8 83 25 $\pm$ 21 31 -6 $\pm$ 16 o 1 1 1
266 1725+044   .29 .9   .8 15 11 81 43 $\pm$ 23 147 -41 $\pm$ 75 d 1 2 4
267 1726+455   .71 .6 .7   755 11 176 -17 $\pm$ 7 89 14 $\pm$ 3 d 1 2 2
268 1730-130 NRAO530 .90 4.2 4.9   599 11 90 20 $\pm$ 12 144 71 $\pm$ 26 o 2 4 4
269 1732+389   .98 1.1 .7   41 7 95 9 $\pm$ 4 129 -1 $\pm$ 16 c 1 1 4
270 1738+476   .32 .9   .9 18 9 46 -41 $\pm$ 8 28 5 $\pm$ 10 c 1 2 2
271 1739+522   1.38 2.0 1.9   1366 13 303 -3 $\pm$ 6 344 -1 $\pm$ 7 c 1 4 4
272 1741-038   1.06 2.3   5.6 2158 13 212 -18 $\pm$ 4 146 16 $\pm$ 4 o 1 3 3
273 1743+173   1.70 .9   .9 29 8 116 -36 $\pm$ 17 264 25 $\pm$ 12 d 1 2 4
274 1745+624   3.89 .6 .6   411 10 138 3 $\pm$ 9 103 -10 $\pm$ 7 d 2 2 2
275 1749+096   .32 2.5   1.1 1545 13 189 5 $\pm$ 4 203 -3 $\pm$ 6 c 1 2 2
276 1749+701   .77 1.1   1.1 20 6 36 63 $\pm$ 16 76 -42 $\pm$ 18 d 2 4 4
277 1751+288         1.1 16 6 17 25 $\pm$ 9 24 -45 $\pm$ 29 o 1 2  
278 1758+388   2.09 .9   .6 24 8 97 10 $\pm$ 17 124 -61 $\pm$ 15 c   4 4
279 1800+440   .66 1.0   .8 12 6 56 -79 $\pm$ 23 24 -60 $\pm$ 9 d 1 4  
280 1803+784   .68 2.6   2.6 1942 13 199 -3 $\pm$ 3 152 0 $\pm$ 3 c 1 2 2
281 1806+456   .83 .7   .5 12 7 92 -77 $\pm$ 52 32 -32 $\pm$ 15 c   4  
282 1807+698 3C371 .05 1.7   3.1 249 13 71 12 $\pm$ 3 84 7 $\pm$ 4 c 2 2 2
283 1815-553           145 13 103 33 $\pm$ 39 102 23 $\pm$ 24 o   2 2
284 1821+107   1.36 1.2 .9   19 8 39 47 $\pm$ 26 34 36 $\pm$ 29 c 1 2  
285 1823+568   .66 1.7   1.6 164 11 98 -1 $\pm$ 8 93 23 $\pm$ 8 d 1 1 1
286 1830+285   .59 1.0   1.3 11 7 62 5 $\pm$ 23 27 3 $\pm$ 20 d 2 1 1
287 1831-711   1.36 1.1 1.3   19 8 102 151 $\pm$ 39 9 3 $\pm$ 8 c   4 4
288 1842+681   .47 .9   1.2 12 8 58 37 $\pm$ 22 60 44 $\pm$ 17 d 1 2 2
289 1845+797 3C390.3 .06 4.5   7.3 29 11 170 65 $\pm$ 57 187 26 $\pm$ 55 d 2 4 4
290 1849+670   .66 .6 .9   121 7 31 -31 $\pm$ 8 74 63 $\pm$ 6 d 2 4 4
291 1856+737 1856+736 .46 .4 .4   13 7 36 37 $\pm$ 12 48 -69 $\pm$ 10 d 1 4  
292 1901+319 3C395 .63 1.8   3.1 28 10 184 -67 $\pm$ 28 119 68 $\pm$ 25 o 3 4 4
293 1908-201         2.3 387 12 60 0 $\pm$ 8 172 -25 $\pm$ 18 c   2 2
294 1920-211           63 10 124 10 $\pm$ 26 197 53 $\pm$ 49 c   4 2
295 1921-293   .35 14.3 4.6   1358 13 123 1 $\pm$ 7 185 -37 $\pm$ 16 o 1 2 2
296 1923+210           97 10 59 -42 $\pm$ 18 47 -30 $\pm$ 12 c 2 2 2
297 1928+738   .30 3.3   3.0 129 11 99 -20 $\pm$ 10 170 -11 $\pm$ 16 o 2 2 2
298 1933-400   .96 1.4 1.2   26 10 33 5 $\pm$ 11 34 -33 $\pm$ 26 c   1  
299 1936-155   1.66 .8   1.3 46 9 66 17 $\pm$ 18 109 36 $\pm$ 30 c 1 2 2
300 1937-101   3.79 .8   .9 16 9 170 -17 $\pm$ 20 43 -31 $\pm$ 20 c 1 2 2
301 1947+079   2.70 .7   .5 28 6 112 87 $\pm$279 175 935 $\pm$239 n   4 4
302 1954+513   1.22 1.6   1.4 43 10 40 3 $\pm$ 10 45 -18 $\pm$ 12 d 1 1 1
303 1954-388   .63 2.0   1.0 373 11 56 12 $\pm$ 10 88 -34 $\pm$ 20 d   2 2
304 1958-179   .65 2.7   1.1 839 13 98 4 $\pm$ 4 90 2 $\pm$ 6 o 1 1 1
305 2000-330   3.78 1.0   1.1 21 9 85 -125 $\pm$ 56 107 27 $\pm$155 d   4  
306 2007+777   .34 1.3   1.2 241 11 303 45 $\pm$ 13 56 3 $\pm$ 3 o 1 4 4
307 2008-159   1.18 .9   .6 84 11 88 15 $\pm$ 15 139 -72 $\pm$ 33 o 1 4  
308 2021+317           13 8 35 -35 $\pm$ 24 42 16 $\pm$ 24 d 1 1  
309 2029+121   1.22 1.3   1.1 20 8 34 -10 $\pm$ 13 38 -54 $\pm$ 30 d 1 4 4
310 2037+511 3C418 1.69 3.8   5.0 353 12 54 0 $\pm$ 3 45 1 $\pm$ 3 d 3 1 1
311 2037-253   1.57 .7   .9 11 6 66 184 $\pm$ 19 63 -149 $\pm$ 29 c   4  
312 2052-474   1.49 2.5 3.0   70 12 106 -22 $\pm$ 31 111 -22 $\pm$ 49 d   2 4
313 2059+034   1.01 1.4   .6 12 10 48 -32 $\pm$ 8 63 -13 $\pm$ 20 d 1 2 4
314 2106-413   1.05 2.3 2.1   22 9 123 79 $\pm$ 28 59 -21 $\pm$ 25 d   4  
315 2109-811           14 5 18 -50 $\pm$ 30 78 152 $\pm$148 d   4  
316 2113+293   1.51 1.5   1.1 139 11 61 -8 $\pm$ 5 371 15 $\pm$ 34 d 1 3 3
317 2121+053   1.94 3.2   2.5 851 13 397 78 $\pm$ 10 73 -1 $\pm$ 3 o 1 4 4
318 2126-158   3.28 1.2   .9 180 12 96 6 $\pm$ 13 70 -74 $\pm$ 15 c 1 4 4
319 2128-123   .50 2.0   1.7 700 12 249 37 $\pm$ 27 234 20 $\pm$ 47 o 2 2 2
320 2131-021   1.28 2.1   2.2 15 8 19 -63 $\pm$ 4 22 99 $\pm$ 16 c 1 4  
321 2134+004 2134+00 1.93 11.5   6.5 909 13 70 -38 $\pm$ 18 94 -40 $\pm$ 26 o 1 2 2
322 2136+141   2.43 1.1   1.2 278 12 122 24 $\pm$ 9 49 -19 $\pm$ 5 d 1 2 2
323 2143-156   .70 .5   1.0 18 9 84 17 $\pm$ 17 213 -55 $\pm$109 d 2 4  
324 2144+092   1.11 1.0   .8 24 9 507 35 $\pm$ 9 142 -29 $\pm$ 15 c 1 4  
325 2145+067   1.00 4.4   3.1 1696 13 439 -5 $\pm$ 14 180 22 $\pm$ 7 d 1 4 4
326 2149+056   .74 1.0   1.1 40 12 419 -72 $\pm$ 52 222 -46 $\pm$ 70 c 1 4 4
327 2149-307 2149-306 2.35 1.3   1.4 16 6 112 -21 $\pm$ 50 90 -4 $\pm$ 53 o   1  
328 2150+173     1.0   1.1 21 6 131 -57 $\pm$ 50 82 -30 $\pm$ 34 d 2 4 4
329 2155-152   .67 1.7   1.8 61 10 231 76 $\pm$ 67 166 193 $\pm$ 67 o 1 4 4
330 2200+420 VR422201 .07 2.9   4.2 955 12 134 -10 $\pm$ 6 268 0 $\pm$ 10 o 1 2 2
331 2201+315   .30 2.8   2.0 305 13 167 11 $\pm$ 8 296 32 $\pm$ 12 o 1 2 2
332 2209+236         .7 18 11 69 42 $\pm$ 22 31 15 $\pm$ 12 d 1 2 2
333 2210-257   1.83 .8   .9 11 6 80 43 $\pm$ 11 71 -61 $\pm$ 15 c   4  
334 2216-038   .90 1.6   1.6 441 12 94 4 $\pm$ 8 211 24 $\pm$ 30 o 1 2 2
335 2223-052 3C446 1.40 4.1   5.2 248 9 165 36 $\pm$ 15 206 -73 $\pm$ 23 c 3 4 4
336 2227-088   1.56 1.4   1.3 61 11 153 52 $\pm$ 20 67 -63 $\pm$ 19 c 1 4 4
337 2229+695     .8 .6   18 9 82 -98 $\pm$ 36 59 -12 $\pm$ 25 d 1 4 4
338 2230+114 CTA102 1.04 4.0 4.9   158 12 185 21 $\pm$ 10 77 -18 $\pm$ 7 o 2 2 2
339 2232-488   .51 .9 .8   13 6 41 116 $\pm$ 46 44 -104 $\pm$145 d   4  
340 2233-148   $\ge$.61 .6 .5   18 9 72 77 $\pm$ 35 31 -97 $\pm$ 36 c 1 4  
341 2234+282   .80 1.1   .9 1689 13 384 -73 $\pm$ 9 264 -45 $\pm$ 6 c 1 4 4
342 2243-123   .63 2.7 2.7   369 12 113 26 $\pm$ 11 350 -88 $\pm$ 46 o 1 4 4
343 2245-328   2.27 .6 2.0   31 10 44 70 $\pm$ 20 58 -84 $\pm$ 45 c   4  
344 2251+158 3C454.3 .86 10.0   10.5 1067 10 296 -222 $\pm$ 58 73 5 $\pm$ 28 o   4 4
345 2253+417   1.48 1.0   1.5 40 9 48 -21 $\pm$ 11 78 42 $\pm$ 23 c 1 2 2
346 2254+024   2.09 .5 .5   23 9 116 71 $\pm$ 54 87 -118 $\pm$ 62 c 1 4 4
347 2254+074   .19 .5   .9 20 9 79 -69 $\pm$ 14 27 -16 $\pm$ 7 d 1 4  
348 2255-282   .93 2.1 1.4   886 13 124 -3 $\pm$ 9 100 -15 $\pm$ 11 o 2 2 2
349 2318+049   .62 1.0 1.2   125 11 103 12 $\pm$ 19 48 12 $\pm$ 28 c 1 1 1
350 2319+272   1.25 1.1   1.1 27 10 282 32 $\pm$ 42 176 88 $\pm$ 26 d 1 4 4
351 2320-035   1.41 .4   .8 66 11 79 40 $\pm$ 22 101 -92 $\pm$ 50 c 2 4 4
352 2326-477   1.31 2.1 2.4   28 7 141 -79 $\pm$157 28 -69 $\pm$ 57 d   4  
353 2328+107   1.49 1.0   1.0 13 6 16 32 $\pm$ 20 53 115 $\pm$ 66 c 2 4  
354 2329-162   1.15 1.9   1.2 11 5 28 100 $\pm$ 27 37 -48 $\pm$ 40 d 2 4  
355 2331-240   .05 .9   .9 22 9 161 -102 $\pm$ 57 113 43 $\pm$ 54 c   4  
356 2335-027   1.07 .6   .6 28 10 74 14 $\pm$ 36 107 -14 $\pm$ 80 c 1 1  
357 2337+264         1.0 15 9 147 271 $\pm$ 44 197 308 $\pm$ 91 o 3 4 4
358 2344+092 2344+09A .67 1.4   1.9 27 11 412 169 $\pm$ 94 507 203 $\pm$162 c 2 4 4
359 2345-167   .58 3.5 4.1   130 10 147 16 $\pm$ 32 86 -94 $\pm$ 32 o 1 4  
360 2351+456   1.99 1.5 1.4   28 8 36 -15 $\pm$ 20 29 24 $\pm$ 20 o 2 1 2
361 2355-106   1.62 1.6 .5   139 11 161 6 $\pm$ 20 175 17 $\pm$ 40 c 1 2 2
362 2356+385   2.70 .7   .5 206 7 73 41 $\pm$ 4 141 -82 $\pm$ 11 c   4 4




Copyright ESO 2003