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Date and Time of the Query: 2019-08-24 T19:15:41 PDT
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Notes for object PKS 0454-234

8 note(s) found in NED.


1. 2005A&A...435..839T
Re:0454-234
4.2 Previously identified inverted-spectrum sources
B0454-234: this source is an HPQ at z = 1.003. It was classified as a
GPS source by Tornikoski et al. (2001) but the new dataset shows a
declining spectrum inverted only during the outbursts. This source is
also labelled as flat because the variability (Var_{DELTA}S,max_ =
3.05) is not high enough for the idb classification.

2. 2004ApJS..155...33S
Re:VSOP J0457-2324
VLBApls image has a faint component extending off the core to the
west.

3. 2004A&A...424...91E
Re:PKS J0457-2324
J0457-2324: noted as a new source with a GPS-type spectrum by Tornikoski
et al. (2001), with turnover at 3 GHz. Possible core-jet morphology in
the VLBA observations of Fomalont et al. (2000).

4. 2001ApJS..134..181J
Re:PKS 0454-234
0454-234. - The 2.3 and 8.5 GHz images of Fey et al. (1996) show that
this quasar has a core-dominated structure with a weak jet out to 5 mas
along P.A. ~ -130. Our images at 43 GHz (Fig. 8) show an unresolved core,
plus a weak component (B) detected only in 1996 May at a similar P.A. as
at the lower frequencies. The faint structure to the east in 1995.47 is
probably an artifact of the noisy data and limited uv coverage.

5. 2001AJ....121.1306T
Re:PKS 0454-234
B0454-234 (z = 1.003). - This is an HPQ, with an optical polarization
up to p = 27% (Wills et al. 1992). The source exhibits strong variability
from 2 to 230 GHz. Based on only one epoch but simultaneous observations
at 1 and 3.9 GHz (Kovalev et al. 1999), the radio spectrum of this source
seems to be inverted to ~3-4 GHz. During outbursts the spectrum is inverted
all the way up to 20 GHz, but in the quiescent state the spectrum steepens
after 8 GHz.

6. 2000ApJS..131...95F
Re:VSOP J0457-2324
J0457-2324. - The source exhibits a mas-scale structure which, according
to the USNO multiepoch monitoring at 2.3 and 8.4 GHz over the period from
1994 July through 1998 April, undergoes considerable changes in the
brightness distribution and positions of the major structural features.
Our image is qualitatively consistent with the structural pattern of the
source. Notably, the ~4 mas southwest extension visible in our image is
aligned with the 2.3 GHz extension detected at several epochs by the USNO
monitoring. The single-epoch 15 GHz observation by the USNO group indicates
a secondary structure at a distance of ~1 mas towards the southeast which
is consistent with the model fitting of our data. We note a difference of
~90^deg^ in position angles of secondary components in our image and the
5 GHz VLBI image by Shen et al. (1998). Albeit relatively large, this
difference could be attributed to the structural variability in the source
(the images obtained are separated by 3 yr).

7. 1998AJ....115.1357S
Re:PKS 0454-234
PKS 0454-234 (OF-292; Fig. 1g).--This is listed as a BL Lac object (Ledden &
O'Dell 1985) because of its featureless optical spectrum (Wilkes et
al. 1983). An initial redshift determination of 1.009 (Wright, Ables, & Allen
1983) was later refined to z=1.003 (Stickel, Fried, & Kuhr 1989). It is a highly
polarized quasar, with optical polarization up to 27% (Wills et al. 1992).
PKS 0454-234 was detected at marginal significance by EGRET at greater than
100 MeV {gamma}-ray energies (Thompson et al. 1993a).

8. 1998AJ....115.1357S
Re:PKS 0454-234
PKS 0454-234 was detected in the 2.3 GHz Tracking and Data Relay Satellite
System (TDRSS) experiment on a baseline of 1.8 Earth diameters (Linfield et
al. 1989), and in a 22 GHz ground survey on a baseline of 10,000 km
(Moellenbrock et al. 1996). Our 5 GHz VLBI image shows an asymmetric morphology
with a strong core and a compact jetlike component to the northwest at a
position angle of -62^deg^. The brightness temperature of the core as derived
from our model is about 6x10^11^ K. A Doppler beaming factor of 5.3 is estimated
using the X-ray flux density at 1 keV and core structural parameters. For
comparison, a value of 3.6 was derived from the variability timescale (Dondi &
Ghisellini 1995).


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