Date and Time of the Query: 2019-05-21 T18:10:53 PDT
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Notes for object [HB89] 0552+398

6 note(s) found in NED.

1. 2005A&A...435..839T
4.2 Previously identified inverted-spectrum sources
B0552+398: this GPS source (O'Dea et al. 1991) is a bright quasar at
z = 2.36 (Hutchings 1992) with low polarization (p_opt_=2.34,
Wills et al. 1992). It is also known as DA 193. Hutchings (1992) found
a close companion 2.9" to the north connected to the quasar by tidal
interactions. Both lie in a dense group of compact galaxies. Hutchings
(1992) suggested that this source is young because it is compact,
luminous, variable and gigahertz-peaked. Lister & Marscher (1996)
observed a short jet and possibly a counterjet, which can also be the
core of the source. They marked superluminal motion in the jet and
possibly some signs of an extended component which would, if real,
indicate a steep curve in the jet.
The shape in the plot (Fig. 4) is beautifully convex. The peak
frequency of the minima is ~5-8 GHz and of the observed maxima 8-22
GHz. There is variability above the turnover (Var_{DELTA}S_(37GHz) =
3.09) but the low frequency end of the spectrum seems to be quite
steady, the 4.8 GHz data contains observations from over ten years.
The spectral shape of this source is definitely convex, the inverted
part has the greatest spectral index in the sample: 1.46. The
variability is slightly too high to qualify this source to be a
classical GPS by our criteria.

2. 2004ApJS..155...33S
Re:VSOP J0555+3948
The jet to the west, seen in the VLBA2cm1 and VLBA2cm2 images, is
clearly seen in the VSOP image. The data were very well modeled by
two circular Gaussians, one each for the core and jet components.

3. 1999AJ....117.1109H
Re:[HB89] 0552+398
This is a bright, radio-loud QSO at z = 2.36. It lies in a very crowded
field, in which our K-band image clearly shows 20 objects besides the
QSO. Of these, 10 are bright or large enough that they cannot be
companions. Nine of the other 10 objects form a band some 5" wide on
either side of the QSO at least the length of the image (36"). These
objects are compact and in the range of 4 to 6 mag fainter than the QSO.
Table 9 shows their magnitudes and also the H-band absolute magnitudes,
assuming they have standard colors (H-K = 1) for a young population at
this redshift. For brevity, we have omitted from the table those
galaxies that are too bright to be companions. Figure 1 shows the
positions of most of them-a few lie outside the boundary shown because
of the dither. These galaxies appear more luminous than those in other
fields-possibly because there are significant negative K-corrections at
this higher redshift, as would be the case for young populations. As in
all other cases, we have adopted no K-correction. Also, H{alpha} is
shifted into the K band at this redshift, which might increase the flux
if these galaxies have Balmer emission.
The nearest companion lies about 2.9" to the north, and there appears
to be curved connecting luminosity to the QSO, suggesting tidal
interaction (see Fig. 10). We thus have evidence that the QSO is a
member of a dense group of compact galaxies of comparable luminosity to
the host and each other. The FWHM of the companions is 0.35", and all
are round with no structure and a bright nucleus.
The radio source is compact, luminous, variable, and gigahertz-peaked,
and it has structure seen only with VLBI: a weak halo extended more
east-west than north-south. This suggests that the source is young.

4. 1998ApJ...504..702L
Re:DA 193
DA 193 (0552+398)
The low-polarization quasar DA 193 has a classical homogeneous
synchrotron self-absorption spectrum, with a turnover at 5 GHz
(Spangler, Mutel, & Benson 1983). It has been classified as a GHz-peaked
spectrum source (GPS) by O'Dea, Baum, & Stanghellini (1991), and is the
only nonblazar in our sample.
DA 193 has been shown to be extremely compact on both arcsecond
(Dallacasa et al. 1995; Stanghellini et al. 1990) and milliarcsecond
(Fey et al. 1996) scales. The superior resolution of our 43 GHz image
(Figs. 7 and 8), however, reveals a complex source structure. When
considered together with the polarized intensity distribution, there
appear to be at least four possible components in the core region of
this source, as well as a short jet extending to the west. The slight
extension to the east may be a counterjet, but is more likely to be the
core (D), since previous VLBI images taken by Spangler et al. (1983),
Charlot (1990), and Bajkova, Pyatunina, & Finkelstein (1996) show no
structure in this direction. A weak core at this position is consistent
with the low self-absorption turnover frequency, which implies that the
core is either misdirected or relatively inactive.
Bajkova et al. (1996) found a proper motion of 0.03 +/- 0.01 mas
yr^-1^ for component C2, based on three epochs at ~8 GHz (1981.5,
1985.37, and 1994.9). The position of C2 in our 43 GHz image is
consistent with this {mu} value, taking into account a possible shift in
core position attributable to observing frequency (see Lobanov 1998). At
the source redshift of z = 2.365, the proper motion corresponds to an
apparent velocity of 2.2 +/- 0.7 h^-1^ c. The presence of superluminal
motion in this object is of interest, because the jets of GPS sources
generally show very little or no proper motion (Vermeulen & Cohen 1994).
We speculate that DA 193 may be similar to 4C 39.25 (Alberdi et al.
1997), with the jet misdirected at the core but pointed almost directly
along the line of sight farther downstream.
Our polarization image of DA 193 resolves two regions of nearly
orthogonal polarization on either side of C5. A partial cancellation of
polarized flux from these two components may be responsible for the low
polarized flux density at the location of C5. The EVPA in the eastern
polarized region (near D) is parallel to the local jet direction defined
by D, C4 and C5, while that of the western region is at an oblique
angle. Higher resolution polarization observations are needed to
clarify the structural details of the inner jet in this source.
The integrated fractional polarization of the inner 0.5 mas of DA 193
is rather low (~2%). This may partly be due to Faraday depolarization,
since very high (>4700 rad m^-2^) rest-frame rotation measures have
been measured for this source (Junor et al. 1996; O'Dea et al. 1990).
Our data also suggest a very weak extended component located 2.3 mas
to the northwest of D. This component, labeled C1 in Table 2, was not
detected by previous studies, and if real would indicate a substantial
curvature in the jet. Bajkova et al. (1996) detected a component with a
similar P.A. (-58^deg^) in their epoch 1994.9 map at r = 1.19 mas, but
it is not likely that this was C1, since this would imply an excessively
large proper motion of 0.55 mas yr-1 (~40 h^-1^ c for q_0_ = 0).

5. 1998AJ....115.1295K
Re:[HB89] 0552+398
0552+398.--Model fitting of this strong compact source indicates a single-sided
structure with 3.9 Jy in a small core and 1.1 Jy in a jet component.

6. 1976ApJS...31..143W
Re:[HB89] 0552+398
0552+398: The identification was suggested to us by P. Kronberg. The single
strong line (central wavelength 4085,4097 A on two spectrograms) is assumed to
be L{alpha} because of an apparent continuum drop shortward; there is only
marginal evidence for C IV {lambda}1549.

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