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Notes for object 3C 273

45 note(s) found in NED.


1. 2009ApJ...705..962C
Re:3C 273
High-velocity gas toward 3C 273 has been well studied using both HST-STIS and
FUSE data (S03, CSG05). There is a weak high-velocity O VI absorber in this
sight line, but no corresponding feature is detectable in any other absorption
line, including Si III. To establish an upper limit on the high-velocity Si III
column density, we use the velocity extent of the high-velocity O VI feature,
V_LSR_ = 105 to 240 km s^-1^.

2. 2008ApJS..179...37T
Re:3C 273
3.2. 3C 273 The STIS data for 3C 273 (z_qso_ = 0.1583) are of excellent quality
but offer only a short path length over which to detect O VI doublet systems
(0.1144 < z_abs_ < 0.1417). The lowest redshift absorber in our sample, at
z_abs_ = 0.12003 is detected along this line of sight. z_abs_ = 0.12003(Fig. 2;
Table 4).-This narrow, weak, single-component absorber is the lowest redshift
absorber in our sample and is detectable at such a low wavelength ({lambda}_obs_
= 1156A) only due to the high-quality data for the 3C 273 sight line. For both O
VI lines, while noisy, the data show corresponding profiles, and the model fits
are satisfactory for both lines. The line strengths from direct integration of
the data are mismatched (the equivalent width ratio is ~1.0+/-0.4), but neither
line can be weak Ly{alpha} (the system is blueward of the Galactic Ly{alpha}
line). Of the H I lines, only Ly{alpha} is present in our data at such low
redshifts, and the line is unsaturated and well fit by a single component. Due
to the simple structure, we are able to derive b_nt_ = 6.6 km s^-1^ and the gas
temperature, log T = 4.5; see {section} 5.2 for details.

3. 2008ApJS..175..423P
Re:3C 273
3C 273 (Fig. 35) did not have a continuum image; however, the narrowband image
is presented here.

4. 2008ApJ...687..767K
Re:PG 1226+023
(Fig. 36).-Because of the strong bleeding regions from the saturated core, we
did not perform nonparametric aperture photometry. The host is reasonably well
fit with a single bulge component (n = 4). The residual image shows the
well-known jet of this source (3C 273), as well as some diffuse, extended
emission. The boxlike imprint in the residual image results from the PSF image
being smaller than the science image.

5. 2008A&A...484..341R
Re:3C 273
The image of this well known quasar shows an unresolved core at 11.9 micron. The
measured 11.9 micron flux is in agreement with the N-band flux of Sitko et al.
(1982) but 100 mJy higher than the flux quoted in Gorjian et al. (2004).

6. 2007AJ....134..294S
Re:PG 1226+023
PG 1226+023 (3C 273): Some optical data (3200-8183 A) are from 1981 and 1988
observations using the UVITS spectrograph and image dissector scanner (IDS) on
the 2.7 m telescope at McDonald Observatory (Wills et al. 1985).

7. 2007A&A...464..175B
Re:3C 273
1226+023 (3C 273) - This object shows all the characteristics that are typical
of high-luminosity quasars: a flat radio spectrum of the core, strong and rapid
variability in all the observed energy ranges (e.g. McHardy et al. 1999; von
Montigny et al. 1997), variable polarization, and a radio jet with superluminal
motion (e.g. Pearson et al. 1981). Additionally, it shows an optical and X-ray
jet, and a very prominent UV excess, the so-called big blue bump (e.g. Roser et
al. 1996; Jester et al. 2005). In the SEDs the contribution of this component
begins to dominate over the synchrotron one in the optical band (Fig. 3). Since
it is likely due to thermal radiation from the accretion disc, it is not
expected to be strongly variable on short time scales, and indeed the optical
light curves do not show important flux changes over the whole time range (Fig.
2). On the contrary, a noticeable flux increase has recently been observed at 22
GHz, which might propagate also to the lower radio frequencies in the next
future (Fig. 1).

8. 2006AJ....131.1262H
Re:3C 273
1226+023 (3C 273): Figure 7 shows the first 10 mas of the jet of 3C 273 at
15 GHz in 2002 October. The top panel shows Stokes I, the middle panel
shows linear polarization, and the bottom panel shows circular
polarization. Positions where circular polarization measurements or limits
were taken are marked and numbered on the Stokes I map. Figure 8 shows the
fractional circular polarization at these locations as a function of
distance from the jet core. The absolute fractional level of the circular
polarization appears to decrease as distance from the core increases. This
decrease could be tied to decreasing opacity along the jet or a decrease
in poloidal magnetic field strength.
The core of 3C 273 was found by HW99 to have m_c_ ~= 0.5% at three
epochs during 1996. The circular polarization appeared with the emergence
of a new jet component. The core was very opaque at this time, and HW99
showed that the appearance of the circular polarization was tied to the
flattening of the core's spectral index due to the emergence of the new
component. As cataloged in WdP83 and K84, 3C 273 was repeatedly detected
in integrated measurements during the 1970s and early 1980s at 8 GHz and
below, where it had a consistently negative sign of circular polarization.

9. 2005AJ....130.1418J
Re:3C 273
The most prominent features in the images (see Fig. 7) are an
unpolarized core and strongly polarized moving knots B1 and B2, which
both brighten at ~0.8 mas (Fig. 39). Each component becomes strongly
polarized just as it leaves the core region (~0.3 mas from the core;
Fig. 17), while the core has a low polarization (comparable with the
noise level). The similarity of the EVPA and fractional polarization
at 7 (brightest polarized feature), 3, and 1.3/0.85 mm suggests a low
fractional polarization in the core at the high frequencies, where
Faraday effects are not important. This implies that the core has
intrinsically low polarization, which might be caused by a strongly
turbulent magnetic field on scales smaller than the 7 mm synthesized
beam. After they flare, B1 and B2 fade dramatically and expand both
along and transverse to the jet direction. This results in the
formation of new features b1 and bs related to B1, and b2 related to
B2 (Fig. 16). The b components might form in the interaction of
relativistic shocks connected with features B1 and B2 and the
underlying jet flow. These components should have lower apparent
speed than the main disturbances (Agudo et al. 2001), but this is not
the case for bs. Alternatively, the B components are fairly extended
features in a broad jet, and the b knots might represent sections of
the jet where the velocity vectors lie at different angles to the
line of sight. The latter interpretation is supported by the
difference in the projected trajectories of the B and b components
(Fig. 18) and the strong dependence between the projected position
angle and apparent speed of the components, with the more northern
knots being slower (Fig. 40). A substantial velocity gradient across
the jet is also expected according to a model in which the underlying
jet flow has a double-helix structure and a lower Lorentz factor than
that of the disturbances (Lobanov & Zensus 2001). The brightening of
B1 and B2 at ~0.8 mas from the core might be connected with either
(1) a change of the jet direction (a slight curvature of the
projected trajectories of both components is seen in Fig. 18 at this
distance), (2) an intensity peak of the threadlike pattern of the
underlying flow where the local velocity vector bends toward the line
of sight (Lobanov & Zensus 2001), or (3) interaction with the
external medium. However, a stable polarization direction in B2
before, during, and after the flare (see epochs 1999.76, 1999.93, and
2000.07 in Fig. 7) does not support the third possibility.
.
At many epochs the images contain a diffuse, highly polarized (up to
50%) feature, C1, farther down the jet (see Fig. 41) and moving at an
apparent speed of ~7c. According to the time of ejection, C1
corresponds to knot G1 found by Jorstad et al. (2001b). If C1 and G1
are the same feature, it has maintained a nearly constant proper
motion over ~5 yr.

10. 2005A&A...432...15P
Re:3C 273
1226+023 (3C 273) The main feature in the pn spectrum of this
well-known radio-loud QSO is the broad soft excess. A simple
two-component model indeed fails to adequately describe its 0.3-12 keV
emission (see Sect 3.2 and Fig. 2). Our best fit includes two
blackbody components (with kT_BB,1_ ~ 0.1 and kT_BB,2_ ~ 0.24 keV,
respectively) and a power law with a quite flat photon index ({GAMMA}
= 1.60 +/- 0.01). This result confirms the finding by Page et al.
(2004a), based on the same XMM-Newton observation. We also detected
the significant (at >99.9% confidence level) presence of an absorption
edge at 7.4 +0.1-0.2 keV and with an optical depth of {tau} =
0.09^+0.02^_-0.03_. Such an energy centroid suggests that the
absorbing material is weakly ionized (Fe V-XV). The most likely origin
for this edge feature is via reflection in optically thick matter, as
an origin in a line-of-sight plasma is not supported by the RGS data
analysis results published in Page et al. (2004a), which did not
report any absorption features apart from a O VII He{alpha} due to warm
gas in the local intergalactic medium. Consequently, we also tried to
fit the data with a model including a Compton reflection component
(PEXRAV in XSPEC); however this model yielded no statistical
improvement with respect to the best fit model listed in Table 10. The
upper limit for the covering factor of the material irradiated by the
X-ray source is R ={OMEGA}/2{pi} = 0.4. On the other hand, no Fe
K{alpha} emission line (i.e. another hallmark of reprocessing in an
accretion disk) was detected, and the upper limit on the equivalent
width for a narrow line at 6.4 keV was found to be 6 eV. Finally, Page
et al. (2004a) reported evidence for a weak broad Fe line using ten
co-added EPIC observations. However, this line has not been detected
in our data even when the absorption edge has been removed from the
fitting model.

11. 2004ApJS..155...33S
Re:VSOP J1229+0203
(3C 273) A VSOP image made from GOT data can be found in Lobanov &
Zensus (2001). The four-component model-fit does not include the
large-scale structure.

12. 2004ApJ...613..682P
Re:PG 1226+023
PG 1226+023. This is the well-known quasar, 3C 273, which is another I
Zw 1-like object (see PG 0804+761 above) in which the [O III] lines are
strongly blended with Fe II lines (Peterson et al. 1984). The
narrow-line components of H{gamma}and H{beta} are weak in both the mean
and rms spectra. However, there are strong narrow-line residuals in the
H{alpha} region, so the H{alpha} line-width measurements cannot be trusted.

13. 2004ApJ...607..309I
Re:3C 273
3C 273.-The sight line toward the bright quasar 3C 273 was described in
some detail by Savage et al. (1993a). It passes through radio continuum
Loops I and IV (Berkhuijsen, Haslam, & Salter 1971) and the North Polar
Spur (Heiles et al. 1980; Snowden et al. 1995). Galactic radio loops in
general, and Loops I and IV in particular (Iwan 1980), are believed to
be supernova remnants or superbubbles filled with hot gas, so this sight
line is expected to be strongly influenced by the interface between that
hot gas and the denser shell around it. Savage et al. (1993a) note that
the high-ionization lines have average velocities ~10 km s^-1^ more
negative than weaker ionization lines, which they attribute to infalling
hot gas. From analysis of low-ionization lines, Sembach et al. (2001b)
find elemental depletions typical of warm diffuse halo clouds,
consistent with a partial destruction of grains (stripped mantles with
cores remaining). They also note that C IV, N V, and O VI have similar
absorption profiles except for a high positive-velocity wing of O VI,
which they attribute to hot gas being expelled from the Galaxy.
Despite the presence of the radio loops, there was no compelling
reason to exclude the 3C 273 sight line from the general analysis of this
study. (In particular, the proposals of other authors that this sight
line is involved with hot gas flowing in or out argues for its inclusion
in this study of halo gas dynamics.) The resolved N V/O VI and C IV/O VI
ratios found here agree well with the integrated ratios of Sembach et
al. (2001b), as does the integrated O VI column density. The integrated
N V column density agrees well with that of Penton et al. (2000b).

14. 2003ApJS..146....1W
Re:3C 273
3C273.0.-This is among the 10 sight lines with the highest S/N ratio
(28 per resolution element). A detailed investigation of this QSO was
presented by Sembach et al. (2001b). The velocity scale preferred here
differs by 9 km s^-1^ from that adopted by Sembach et al. (2001 b); see
section 3.4 for a discussion of this. Sembach et al. (2001 b) report the
same equivalent widths (within the errors), except that they include the
125 km s^-1^ component into the Milky Way component, and they did not
split the error into a statistical and systematic component. The
relatively large systematic error in the equivalent width of this
component is due to uncertain integration limits.
Both the O VI {lambda}1031.926 and the O VI {lambda}1037.617 lines
can be measured. In the velocity range -70 to 105 km s^-1^ the ratio
N(1037)/N(1031) is 1.13 +- 0.04, suggesting that there might be some
slight saturation.
Two H_2_ components are clearly visible in the J = 0, 1, 2, and 3 lines,
but for J = 4 only one component is seen. The strongest H_2_ component
is associated with the weak H I at 25 km s^-1^ (see Richter et
al. 2003). This H_2_ line has only a minor influence on the systematic
error of the thick disk and HyC O VI components. The features at
1029.161 and 1031.186 {angstrom} are Ly{beta} at z = 0.00335
(v = 1005 km s^-1^) and z = 0.00532 (v = 1595 km s^-1^), which are
associated with the Virgo Cluster (Sembach et al. 2001 b). There are
three small (diameter < 10 kpc),galaxies in this cluster with impact
parameter <300 kpc (NGC 4420, UGC 7612, and UGC 7512). The feature
at 1035.445 {angstrom} is O VI in the Virgo cluster, at v = 1020 km s^-1^.
The corresponding O VI {lambda}1037.617 feature is blended with
low-velocity H_2_J = 3.

15. 2003AJ....126.2237D
Re:3C 273
.
4.8. Blazars
.
Blazars are common in the radio-excess sample; PKS 0235+164
(F02358+1623), PKS 0338-214 (F03384-2129), PKS 0420-014 (F04207-0127),
PKS 0537-441 (F05373-4406), PKS 0735+17 (F07352+1749), PKS 0754+100
(F07543+1004), PKS 0829+046 (F08291+0439), OJ 287 (F08519+2017),
PKS 1144-379 (F11445-3755), 3C 273 (F12265+0219), 3C 279
(F12535-0530), B2 1308+32 (F13080+3237), OQ 208 (F14047+2841), OQ 530
(F14180+5437), B2 1732+389 (F17326+3859), Q2005-489 (F20057-4858),
BL Lac (F22006+4202), and 3C 446 (F22231-0512). These BL Lac objects
are optically variable, flat radio spectrum quasars, or "transition
objects" between traditional BL Lac objects and (strong emission-line)
quasars. Many of the blazars have extremely high radio powers
[L_{nu}_(4.8 GHz) > 10^27^ W Hz-1] and FIR luminosities
[{nu}L_{nu}_(60 micron) > 10^13^L_solar_] and are at relatively large
redshifts (z > 0.9). Blazars also occur in the sample at lower
redshifts and powers, as low as z ~ 0.05 and L_{nu}_(4.8 GHz) ~ 10^25^
W Hz-1. All the known blazars in the radio-excess sample have large
radio excesses (u < -0.2), several with extreme values of u ~ -1.0.
CAB comment that the blazars in their full sample all have u < -0.15
and spectral indices between 1.4 and 4.8 GHz of less than 0.5. This
makes them flat spectrum objects with large radio excesses.

16. 2002ApJS..143..315V
Re:IRAS F12265+0219
F12265+0219 = 3C 273 (IVb). This object is highly nucleated but
shows a thick tidal feature toward the northeast and a very faint feature
to the northwest (e.g., Tyson, Baum, & Kreidl 1982). The faint linear
feature emerging to the southwest is the well-known optical jet in this
system (e.g., Bahcall et al. 1995).

17. 2002ApJS..143..257K
Re:3C 273
1229+0203ra.---The strong absorption feature at 1209--1223 {Angstrom}
does not appear in all spectra that were merged; this may be due to
oversubtraction of geocoronal Ly{alpha} in some of these spectra; we
exclude this region from further analysis. Also, there is no overlap
in the constituent spectra around 1600--1650 {Angstrom}, leaving a
break at the Si IV + O IV.

18. 2002ApJS..140..143B
Re:3C 273
q1226p0219, z = 0.158.-3C 273. The FOS data are discussed in Bahcall
et al. (1991). 3C 273 was observed in SPECTROPOLARIMETRY mode also, but
we did not analyze those data. G270, G130.

19. 2001ApJS..134..181J
Re:3C 273
1226+023 (3C 273). - This relatively nearby object is one of the
brightest flat-spectrum radio sources and the brightest X-ray quasar.
As such, it has been extensively studied at a number of wavelengths
(e.g., McHardy et al. 1999; von Montigny et al. 1997). It is well known
to have superluminal motion (see Porcas 1987), which extends out to at
least 120 pc at 1.7 GHz (Davis et al. 1991). According to Homan & Wardle
(1999), the core of 3C 273 contains significant circular polarization.
In our program the source was observed at three frequencies, which
allows us to trace the jet out to 16 mas at 8.4 GHz and 8 mas at 22 GHz.
The structure of the jet is similar to the description by Mantovani et al.
(1999), who observed 3C 273 at 22 and 43 GHz during 42 days in 1992
December and 1993 January to search for short-term variability. In our
images we identify seven moving components from ~0.5 to 8 mas from the
core. To determine the proper motions of these components, we combine the
results of our model fitting at different frequencies with those of
Mantovani et al. (1999), whose model fits appear to be compatible with
ours. The results are shown in Figures 23d and 23e, where Figure 23d
presents the separation of components from the core in the innermost part
of the jet out to 4 mas, while Figure 23e presents the same for the
segment of the jet between 4 and 10 mas. The values of the proper motions
cover a wide range from 0.3 to 1.6 mas yr^-1^, with a tendency toward
faster motions farther from the core.

20. 2000ApJS..129..563S
Re:3C 273
3C 273 (z_em_ = 0.158). - This QSO was observed with the G130H,
G190H, and G270H gratings (see Table 4 and Fig. 4c). The FOS ISM
absorption lines in the spectrum of 3C 273 have been extensively
discussed in Paper I. That discussion also includes a comparison to the
much higher resolution observations with the GHRS reported by
Savage et al. (1993b). The low-ionization gas along the sight line to
3C 273 is relatively undisturbed, with the average velocity equivalent
width for Mg II of = 111 km s^-1^ compared to the 21 cm emission
extension width of 109 km s^-1^. There are no known HVCs in this
direction, even though the line of sight passes through Galactic Radio
Loops I and IV.

21. 2000ApJS..127...11G
Re:3C 273
3.9. PKS 1226+023 (3C 273)
The 3C 273 blazer is a FSRQ (Wall & Peacock 1985; Padovani & Urry
1992) with superluminal jet (Zensus 1989) and was detected in
{gamma}-ray during EGRET phase 3 observations when it was in a high
{gamma}-ray state (von Montigny et al. 1997). Recently, Courvoisier
(1998) and Turler et al. (1999) described this blazar in detail. We
observed this object on two nights during 1998 January and could not
detect any variations of this source. Results of our observations in B,
V, and R bands are presented in Table 3.

22. 2000A&AS..145....1P
Re:3C 273
1226+023 (3C 273): In this quasar (z=0.158, highly SLM), smooth flux
variations appear. Its modulation index is 6% at 6 cm;

23. 2000A&AS..143..357K
Re:3C 273
3C 273 (PKS 1226+02) was the first QSO discovered. It is classified as a
low polarization quasar (LPQ). The optical variations are usually
relatively small, even the total brightness variation amplitude has been
less than one magnitude (Pica et al. 1988; Sillanpaa et al. 1988a). In
1983 brightness reached 12.17 mag in the V-band (Sillanpaa et al.
1988a). Studies by Fiorucci & Tosti (1996b) and Villata et al. (1997)
did not show any large optical variations.
During our observations on December 1995 3C 273 was brightening rapidly
(Fig. 14) (between JD^bar^ 50065 and JD^bar^ 50070). On January 1996 the
object did not show a continuation of this trend. Part of the
observations on January and February 1996 were simultaneous with an
EGRET-pointing (marked with a box in Fig. 14). In early April 1996
(JD^bar^ 50157) 3C 273 started to fade from mag 12.8 towards mag 13. The
shape of our V-band light curve observed during winter 1996 is also in
agreement with the R-band variations observed by Raiteri et al. (1998)
during the same period. Observations during winter 1997 did not show
large flares, the brightness was near 12.9 mag. The maximum V-band
brightness during years 1995 and 1997 was 12.67 (JD^bar^ 50070) and the
minimum 12.97 (JD^bar^ 50519 and JD^bar^ 50525) mag.

24. 1999MNRAS.308.1159C
Re:3C 273
3.4 3C273
3C273 is famous for its jet, which can be seen in the outermost contours
of our corrected images. The jet is known to emit X-rays at around
16 arcsec (nearer the core than the radio and optical features of the
jet), but the emission from the jet contributes less than 0.5 per cent
of the total X-ray luminosity of the source associated with the quasar
(Harris & Stern 1987). From optical images, 3C273 may be a member of a
poor cluster of galaxies (Stockton 1980).
All the wobble-corrected profiles of 3C273 require the addition of an
extended component (preferably a King law). Each of the models for the
extended emission yields slightly (and consistently) different results:
the broken power-law fits tend to have an R of 8.7 arcsec (where
1 arcsec corresponds to 3.6 kpc at the redshift of the quasar) and
contain 5 per cent of the total X-ray luminosity, at
7 x 10^44^ erg s^-1^. The King law fits show a greater variation in the
parameters, but have an R of only ~ 4 arcsec, and ~ 11 per cent of the
total luminosity at 1.3-2.0 x 10^45^ erg s^-1^. The extended emission
we find in the environs of this quasar is sufficiently luminous that it
cannot easily be ascribed to the jet.

25. 1998ApJ...506..637T
Re:3C 273
This famous quasar was the first to have its spectral redshift
identified (Schmidt 1963; z = 0.158, 1 mas = 3.6 pc) and has been
studied extensively at all wavebands (Perry, Ward, & Jones 1987 and
references therein). VLBI studies of the parsec-scale jet at centimeter
wavelengths reveal typical motions of 0.6-1.2 mas yr^-1^ and components
with lifetimes that vary from ~1 to over 13 years (Abraham et al. 1994;
Zensus et al. 1990).
The first VLBI polarimetry was performed by Roberts et al. (1990) at
5 GHz (epoch 1984.78), who found (1) a fractional polarization that
increased steadily with distance from the core from 0.5%-50%, (2)
polarized intensity dominated by the western ends of the jet in contrast
to the total intensity that is core-dominated, and (3) an
electric-vector position angle in the western part of the jet nearly
orthogonal to the jet axis but that changes more rapidly in the inner 10
mas. They assumed that the RM was identically zero everywhere. They
justified this assumption based on the fact that the integrated RM for
the core measured with the VLA is RM = +5 rad m^-2^ (Rusk 1988), and the
polarized flux density of the western jet contained over 40% of the VLA
polarized flux density. In the inner jet, Roberts et al. recognized that
there may be significant departures in the RM from zero and in fact used
the deviations of the polarization angles from the jet axis at 5 GHz to
infer a RM of 22,000 r^-2.2^ rad m^-2^, which implies an RM of 140 rad
m^-2^ at r ~ 10 mas.
Leppanen et al. (1995) were the first to make polarimetric
observations of 3C 273 (epoch 1994.45) with VLBI at 22 GHz. They found
(1) less than 0.5% polarization in the core, (2) generally disjoint
peaks between the total and polarized intensities, (3) an increase in
fractional polarization with distance from the core, and (4) a roughly
longitudinal magnetic field orientation in the inner 2 mas that becomes
misaligned at larger core distances (in direct contrast to the finding
of Roberts et al. 1990). Again, they assumed an identically 0 RM
throughout.

26. 1998ApJ...506..637T
Re:3C 273
In Figure 1a I show an image of the polarized intensity overlaid on
the total intensity image at 15 GHz. Rough agreement can be found in
both total intensity and polarized structure with the images of Leppanen
et al. (1995). I have therefore adopted their labeling of the
components (F1 -F7), although there is a difference of nearly 2.5 yr
between our observations and my lower resolution results in the blending
of some of these components. The core (F7) is found to be weakly
polarized at the level of ~2% (see Table 3). This contrasts with the
lower fractional core polarization seen by Leppanen et al. and by
Roberts et al., but given the variable nature of radio cores this result
is not surprising. The polarized flux density increases with distance
from the core reaching 27% at a distance of 10.6 mas at component F1.
The change in polarization angle with wavelength in the western jet
(component F1) can be well fitted with a {lambda}^2^ law fit. The derived
Faraday RM between 8 and 15 GHz is 200 +/- 30 rad m^-2^ and between 5 and
8 GHz (at lower resolution) is 80 +/- 20 rad m^-2^. This is still larger
than the +5 rad m^-2^ integrated RM found by Rusk, but this value will
also be influenced by polarized flux density from more distant jet
components not sampled by the VLBA. With increasing proximity to the
core, the RM appears to increase (see Fig. 2), going up to 800 rad m^-2^
at the position of component F4/5. Note that an RM of 800 rad m^-2^
corresponds to a change in {chi} of 164^deg^ at 5 GHz!
Failure to account for the RM may lead to gross mistakes in
understanding the underlying magnetic field of the jet. At the core, the
change in polarization angle with frequency is not well fitted by a
{lambda}^2^ law between 8 and 15 GHz. This could be caused by
spectral-index effects and a blending of components within the
synthesized beam (see section 4). The RM-corrected magnetic field
orientation is shown in Figure 3. Outside the core, the magnetic field
runs parallel to the local jet direction.

27. 1998ApJ...495..152L
Re:3C 273
3C 273.--BKS95 detect a host with a brightness that is greater than L*, but
they see no companions. McLeod & Rieke (1994) see the jet to the northwest in
their H-band frame and a second feature that is just south of west. Stockton
(1980) found four galaxies within 250 kpc with velocity differences of -80,
300, 530, and 510 km s^-1^. This quasar is probably in a poor cluster.

28. 1998ApJ...492..116S
Re:3C 273
3C 273.--HST images of the radio-loud QSO 3C 273 (Bahcall et al. 1997), as well
as previous ground-based images by us and others, clearly show an optical
"jetlike" feature extending to the southwest from the optical nucleus and
reveal the presence of a fairly luminous host galaxy. However, there is no
obvious evidence of a previous interaction/merger, and the extreme brightness
of the nucleus as well as the relatively short HST exposure times make the
identification of any circumnuclear knots that might be present extremely
difficult.

29. 1998AJ....116.2682C
Re:IRAS 12265+0219
3C 273. Quasar. Radio and optical variable. High-resolution maps of
the radio jet in Bahcall, Kirhakos, & Schneider (1995).

30. 1998AJ....115.1357S
Re:PKS 1226+02
PKS 1226+023 (3C 273; Fig. 1m).--This well-known radio source has been
identified with a 13th magnitude object at a redshift of z=0.158 (Hazard,
Mackey, & Shimmins 1963; Schmidt 1963). It shows optical variation, which was
first analyzed by Smith & Hoffleit (1963), but does not have high optical
polarization (Appenzeller 1968). It is very bright across the wave bands from
radio to {gamma}-rays. It was the only {gamma}-ray source known before the CGRO
observations (Swanenburg et al. 1978; Bignami et al. 1981), and one of the
first two extragalactic sources detected by EGRET (Mattox et al. 1997 and
references therein).
The large-scale structure from the VLA and MERLIN shows a compact, flat-spectrum
core and a single jet extending about 23" from the core at a position angle of
222^deg^ (Conway et al. 1993). This source has received considerable attention
since the VLBI technique became available, due mainly to its intensity and
variability. Multifrequency VLBI observations show a bright core and a number of
jet components extending toward the southwest (see, e.g., Davis, Unwin, & Muxlow
1991; Zensus et al. 1988).
Our VLBI observation of this equatorial quasar has a good north-south resolution
with a beam of 1.6 mas x 0.88 mas at a position angle of 33^deg^. We fitted
six components, labeled 1 through 6, to the data. The strong component 1 at the
eastern end is identified as the core. No counterjet is visible. Components 2-6
are jet components, or knots in the continuous jet, which have a similar
position angle of ~230^deg^ and increasing distance to the core (from 1.9 mas
for component 2 to 15.2 mas for component 6). Along this position angle, there
is a distinct emission gap between components 5 and 6. Such morphology is
consistent with other published results (e.g., Zensus et al. 1988). Comparison
with earlier observations enables us to identify the components in our image
with those seen previously: our components 2, 3, and 4 are respectively C_10_,
C_9_, and C_8_ (Abraham et al. 1994). Our component 5 is C_7a_ (Cohen et
al. 1987). The more extended component 6 in our image is more difficult to
identify and may be C6 (Unwin et al. 1985; Zensus 1987; Charlot, Lestrade, &
Boucher 1988) or possibly a mixture of C_6_ and other components (such as C_5_,
C_4_, or even C_3_) (see Cohen et al. 1987; Unwin et al. 1985). Such
identification is in good agreement with the observational picture of the
evolution of the different components in 3C 273 (see Abraham et al. 1996).

31. 1998AJ....115.1295K
Re:3C 273
1226+023.--The well-known jet in 3C 273 continues out to a much farther distance
(Davis, Unwin, & Muxlow 1991) than shown in our image, which is sensitive only
to the higher surface brightness structure.

32. 1998A&AS..131..451R
Re:3C 273
This quasar is a classical superluminal source (Zensus 1987). The mas
jet can be seen extending from the core out to more than 150mas (Unwin
1990), and the PA of this jet is well aligned with the arc-second scale
jet (Davis et al. 1985). VLBI monitoring of this source at {lambda}1.3cm
(Zensus et al. 1990) shows two features moving out from the core, with
{mu} = 0.65 and {mu} = 0.92 microas/yr respectively. A prominent feature
is the twisting of the jet, seen in both total intensity maps and
polarization maps (Leppanen et al. 1995), with an increase in
polarization with distance from the core.
A 3mm observation made by Krichbaum et al. (1990), showed jet
components being ejected after a major optical outburst. Baath et al.
(1991) showed a core with a bent jet, with several components at
different PA's, suggesting that the wiggling seen at mas scales
continued at microas scales. The 1988 map showed an elongated component
emerging at the time, which could be related to an outburst, seen 60
days earlier in Optical/IR (Courvoisier et al. 1988). Krichbaum et al.
(1996b) showed 2 new epochs (1994 & 1995) which clearly show the fast
(0.5-0.6 mas/yr) superluminal motion in 3C 273.
The 1990 map (Fig. 9) shows an unresolved core and a component in the
same PA as seen in earlier 3mm maps of this source. We do not see the
other components but they may be too weak to be detected with the
limited dynamic range we have in this map. Most of the single dish flux
density (Table 2) is missing, suggesting that the major part of the
{lambda}3mm flux density is emitted by the extended jet. The result from
a Gaussian model fit to the UV data can be found in Table 12. Both
methods agree on the general location and flux densities of the fitted
components.
We are unable to determine the proper motion in this source as the
previous epoch map was made in 1998 March and the structural changes
have been too large to identify the components and determine their
motions.

33. 1997MNRAS.286..513R
Re:3C 273
7.2.2 3C 273
The radio-loud quasar 3C 273 is the most luminous object of the current sample
by more than an order of magnitude. The addition of a broad Gaussian at
energies characteristic of iron K{alpha} emission leads to a change in the
goodness of fit parameter by {DELTA}{chi}^2^=32 for three additional degrees of
freedom (with best-fitting parameters reported in Table 4). The F-test shows
this to be a significant improvement at more than the 99 per cent level. This
is contrary to the result of Yaqoob et al. (1994) who find no significant iron
line emission. This discrepancy is understandable given small high-energy
calibration issues (associated with the X-ray mirror response) that affected
the early response matrices. The analysis presented here should be more
reliable at detecting comparatively weak broad features at high energies.

34. 1997ApJ...487..536S
Re:3C 273
This source is known for its strong and variable soft excess (Leach et
al. 1995). The longest ROSAT archival exposure used here (Table 1) can
equally be fitted by a concave broken power law ({GAMMA}_soft_ = 2.10_-
0.04_^+0.06^, {GAMMA}_hard_ = 1.87_-0.06_^+0.04^, E_0_ = 0.64 +/- 0.15
keV, {chi}_r_^2^ = 1.06/181), or by a power law plus Galactic N_H_ plus a
blackbody of temperature kT = 0.065_-0.014_^+0.07^ keV, photon index
{GAMMA} = 1.82 +/- 0.06, {chi}_R_^2^ = 1.02/181. Our results do not
compare directly to Leach et al. (1995), who fixed the high-energy slope
to 1.5, the value from the GINGA data. Fitting the data with a power law
plus Galactic N_H_ plus edge yields a fit equivalent to the previous
models,{chi}_r_^2^ = 1.03/181, with the following parameters:
{GAMMA} = 1.97 +/- 0.02, E_e_ = 0.54 +/- 0.05, {tau} = 0.25 +/- 0.07. The
edge energy is consistent with the K edge of O II-VI in the quasar's
rest frame.

35. 1997ApJ...479..642B
Re:3C 273
(PG 1226+023).-The host galaxy is an elliptical. The V magnitude
estimated from the McLeod & Rieke (1994b) H-band images is in good
agreement with the magnitude determined by our two-dimensional model.
Using deep ground-based CCD images, Tyson et al. (1982) obtained M_V_
~ -22.5 for the host, which is in good agreement with our best two-
dimensional model magnitude of M_V_ = -22.1. The host is somewhat
brighter than the brightest galaxy in a rich cluster. Stockton (1980)
measured redshifts for galaxies in the 3C 273 field and found that four
of them have redshifts similar to the quasar, in agreement with the
suggestion of Bahcall & Bahcall (1970). One of those galaxies was
detected (a spiral galaxy) in WF4: it lies at 75" east of the quasar
(~33 kpc), and its redshift is z = 0.1577. Wyckoff et al. (1981) obtained
R = 16.3 for the host, which is equivalent to M_V_ ~ -21.3 mag. The inner
part of the jet is barely visible in the PSF-subtracted image in Figure
2. HST and Merlin observations of the 3C 273 jet are reported in Bahcall
et al. (1995d).

36. 1997A&AS..121..119V
Re:3C 273
3.9. 3C 273(1226+023)
This is a very bright and consequently very famous quasar. Among its main
features one can quote the optical jet and the existence of a UV excess (blue
bump) in the spectrum, whose luminosity is comparable with or even greater than
the {gamma} one. The source does not show a high optical activity: variations
less than 1 mag were reported after several years of observations. An optical
flare was detected at the beginning of 1983 (Sadun 1985; Sillanpaa et al.
1988), the visual magnitude reaching 12.17. The first detection of 3C 273 at
{gamma} energies was obtained by the COS B satellite in July 1976 and then in
June 1978. Subsequently, it was observed by the instruments OSSE (50keV-10MeV),
COMPTEL (1-30MeV), and EGRET (30 MeV-20 GeV) on board CGRO. This allowed to
reconstruct the spectrum of the quasar in the {gamma} band (Johnson et al.
1995).
The results of our monitoring campaign for 3C 273 are presented in Tables 21-23
and in Figs. 18 and 19. For the magnitude calibration we have adopted the field
comparison stars chosen by Smith et al. (1985). Our photometric calibration in
the R and B bands (see Table 4) gave results in good agreement with those
determined by the above authors. The box in Fig. 19 shows the period of EGRET
pointing. We have not observed significant variations in the source brightness
during all the considered period.

37. 1996ApJS..104...37M
Re:3C 273
3C 273.--Strong Fe II_UV_ and He II {lambda}1640 as well. C IV {lambda}1549
shows a prominent red wing. 3C 273 is a well-known core-dominated,
superluminal source with {beta}_app_ ~8.0+/-1.0 (Vermeulen & Cohen 1994).

38. 1995ApJS..100...37G
Re:3C 273
3C 273 is a superluminal source (Zensus 1989), and it has been
classified as an RBL object (Giommi et al. 1990; Hewitt & Burbidge 1993).
This blazar was observed with EXOSAT on six occasions between 1984 and
1986. Both EXOSAT and Ginga observations of this source have been
described by Turner et al. (1990 and references therein). We used the
power-law plus absorption model to fit the EXOSAT spectra of 3C 273, but
the derived values of N_H_ are smaller than the Galactic value. Next we
fitted the spectra using the power-law plus fixed absorption model, and
the results are listed in Table 3. It can be seen from this table that
the reduced x^2^ values are very large, which suggests that the fits to
the spectra are not acceptable. Then we tried to fit the spectra using
all the models mentioned in Section 4.1. From the F-test analysis (using
Tables 3, 4D, and 4E), we find that the power-law plus blackbody and
thermal bremsstrahlung plus fixed absorption models fit the spectra best,
and also these two models are highly significant (>99.99%) over the
power-law model. Simultaneous multifrequency observations of this source
were carried out at different epochs (Lindau et al. 1986; Courvoisier et
al. 1990 and references therein), and the results of such observations
were used to construct the multifrequency spectrum of this RBL (Fig. 3i),
which can be represented by two parabolic curves.

39. 1995ApJ...447..121W
Re:3C 273
3C 273.-We confirm the spectral complexity previously seen in the HEAO 1
data (Worrall et al. 1979). To model the data with reprocessing we
require the Compton hump to turn over at ~20 keV. However, the upper
limit to the Fe K line EW (20 eV) is too small for the amount of
reflection observed, assuming the line and the Compton hump have a
coincident origin. An Fe K line was detected by Ginga (Turner et al.
1989).

40. 1994AJ....108.1163K
Re:3C 273
1226+02: (3C 273) Source structure taken from Conway et al. (1993).

41. 1994AJ....107.1219E
Re:3C 273
3C 273. The absorption spectrum of this quasar (z = 0.158) and the
galaxies near the line of sight have been studied extensively by Morris
et al. (1993). Here we note only that this quasar is not located in a
particularly rich environment (B_gq_ = 28 +/- 27) and also shows no
associated metal-line absorption.

42. 1994A&A...289..673T
Re:3C 273
1226+023 (3C273)
3C 273 is a remarkably well-monitored source at our radio frequencies but
the optical data set especially from the last few years is unfortunately
undersampled. This is one of the three sources of which we have also
sufficient 230 GHz data for correlation analysis. Earlier analyses of
optical and radio connections in this source (L. Valtaoja et al. 1990;
Robson et al. 1993) have shown a clear correlation between the optical
and radio events at least during some flares, and our flux curves show
that the rise in the optical flux in ca. 1988.2 was soon followed by a
flare at all radio frequencies with a timelag which increased towards the
lower frequencies (0-50 days at 230 GHz, 50-100 at 90 GHz, ca. 200 at 37
GHz). There is a very clear correlation between all the events at all
four radio frequencies, with time delays ranging from 50 to 100 days (230
GHz to 22 GHz) to 0-50 days (230 GHz to 90 GHz, 37 to 22 GHz).

43. 1993MNRAS.263..999T
Re:PKS 1226+02
1226+02 (3C 273). Quasar spectrum, extensively studied: strong, broad
Balmer and Fe II lines, blue continuum, [O III] {lambda}5007 of small
equivalent width. [O III] {lambda}5007 may be contaminated by Fe II
emission.

44. 1991ApJ...381...85T
Re:3C 273
This quasar exhibits its usual flat X-ray spectrum. The observations presented
here show a significant improvement to the spectral fit by the addition of a
Gaussian line to the model. IPC data suggest a soft excess best fitted by a
cool blackbody (kT=0.0061 keV), which would not be visible in the SSS data.
Turner et al. (1989) report soft excess variability between the EXOSAT
observations of this source.

45. 1964ApJ...140...35M
Re:3C 273
No. 28.-Redshift by Schmidt (1963) .


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