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Notes for object FBQS J0050-0929

13 note(s) found in NED.


1. 2005A&A...435..839T
Re:0048-097
4.2 Previously identified inverted-spectrum sources
B0048-097: is a typical BL Lac object: it is highly polarized
(p_opt_=10.6% Wills et al. 1992), bright, variable and its line
spectrum is featureless preventing the redshift determination
(Gabuzda et al. 1999). However, a lower limit of z~0.2 was derived by
Stickel et al. (1993) from the absence of the extended nebulosity of
the host galaxy. In VLBI imaging Gabuzda et al. (1999) found the source
to be very compact but there was evidence for a single jet. Also a
secondary jet is possible, but greater resolution is required to ensure
it.
.
This source was regocnized as an inverted-spectrum source with a
turnover at 10 GHz by Tornikoski et al. (2001). Simultaneous data from
the end of 1992 from Hartebeesthoek Radio Astronomy Observatory
(HartRAO) and Metsahovi Radio Observatory show that the spectrum is
inverted up to 22 GHz when activity is medium. There is a significant
amount of activity especially at frequencies above 5 GHz, the lower
envelope of the spectrum is flat and the upper is clearly convex.

2. 2001AJ....122..565R
Re:PKS 0048-09
PKS 0048-097. - A very weak emission line may be detected at 6092 A in
both our MMTO 4.5 m and KPNO 2.1 m spectra. It is plausibly
[O III] {lambda}5007 at z = 0.216 because Ly{alpha} may be present in the
IUE spectra at this redshift (Lanzetta, Turnshek, & Sandoval 1993).
Alternatively, there is evidence that the redshift for this source is
higher. Falomo (1996) reports that it is optically unresolved and,
assuming a host elliptical of M_R_ = -23.5, sets a lower limit to the
redshift of z > 0.5.
The presence of a hotspot near the leading edge makes this source a
plausible "dogleg" FR 2 similar to 3C 270.1 and 3C 275.1 (Stocke,
Burns, & Christiansen 1985). The radio structure sets no firm limits on
the distance to this object; however, its FR 2-like radio structure does
suggest that [O II] {lambda}3727 at z = 0.634 is a more likely
identification for the weak emission line at 6092 A. At this redshift,
PKS 0048-097 would have an extended radio luminosity more commensurate
with an FR 2 (log P_ext_ = 26.23). This redshift is also in agreement with
Falomo (1996). However, because both lines are so weak, we choose not to
adopt either redshift.
Because it is unresolved by ground-based, optical observations (SFK93),
we assume z > 0.2 for luminosity and linear size calculations rather than
either tentative redshift.

3. 2001AJ....121.1306T
Re:[HB89] 0048-097
B0048-097. - This is a relatively well-studied BL Lac object, with
strong variability across the whole frequency range. The old catalog data
from PKS and K1 seem to represent a relatively high state of the activity
cycle. Even the shape of the quiescent spectrum, however, remains slightly
inverted up to 10 GHz. During the outbursts the spectrum is highly
inverted up to ~10 GHz, from where it remains relatively flat up to
90 GHz.

4. 1999MNRAS.307..725G
Re:[HB89] 0048-097
3.1 0048-097
This is a bright, strongly variable, point-like optical source, with
no indication of spectral features either in emission or absorption
(Pica & Smith 1983; Stickel, Fried & Kuhr 1993; Falomo, Scarpa &
Bersanelli 1994), so that its redshift remains unknown. The object is
unresolved in the Hubble Space Telescope image of Falomo (1996), who
sets a lower limit on the redshift z > 0.5 based on the assumption that
the host galaxy is an elliptical with M = -23.5. The VLBI image of
Shen et al. (1997) for 1992 November shows a faint extension in
structural position angle ~ -160^deg^, however it is difficult to
estimate the reliability of this feature, because their images were
obtained with extremely sparse u - v coverage.
Although our VLBI images are very compact (Fig. 1), we find evidence
for a jet to the southeast, at position angle {theta} ~ 165^deg^. The
evidence for the secondary (jet) component from the I data is not
conclusive, but we nonetheless feel that the jet is likely to be real,
because we detect a P double structure that corresponds well to the
compact I double structure. The results of our model fitting indicate
that the core is relatively weakly polarized, m ~ 2 per cent, but the
jet component is quite highly polarized, m ~ 45 per cent. The direction
of polarization in the core does not bear any obvious relation to
{theta}, but {chi} in the jet component is nearly perpendicular to
{theta}.

5. 1999ApJS..121..131F
Re:[HB89] 0048-097
There is no redshift available for this polarized (P_3.7_ =9.3%:
Wardle 1978; P_opt_ =1%-27%: CH84, Brindle et al. 1986) object. Very
faint infrared fluxes have been observed by Gear (1993), so this object
has the largest infrared variation of the objects discussed in the
present paper. The infrared variations are {DELTA}J=6.55, {DELTA}H=6.23,
and {DELTA}K=6.07, while that in the optical band is 2.7 mag (Angel &
Stockman 1980). We can expect that the optical monitoring should reveal
a similar amplitude. For color-color indices, there are correlations for
(J-K) and (J-H) and for (J-K) and (H-K): (J-K)=1.20(J-H)+0.61 with
r=0.69 and p=5.x10^-4^, and (J-K)=4.7(H-K)-2.13 with r=0.64 and
p=2.x10^-3^. However, no correlation was found for (J-H) and (H-K). For
the color indices and the magnitudes, there are correlation indications
of (H-K) increasing with J (p ~1%) and (J-K) with H (p~0.3%) (see
Figs. 2d and 2e).

6. 1999A&AS..139..601C
Re:[HB89] 0048-097
0048-097: Figure 1 shows the A+B configuration image. The core emission
is located at the center of a diffuse structure and a bright knot
(hot-spot?) is seen at the southern edge of the radio source. The
4.88 GHz image (Fig. 2) from the B array does not show all the extended
structure seen at lower frequency. The image at 1.46 GHz published by
Wardle et al. (1984) only shows the core and a hint of the southern
knot. We find a flux density of 176 mJy in the extended emission to be
compared to the 95 mJy reported by Antonucci & Ulvestad (1985) based on
the image of Wardle et al. (1984). 0048-097 appears only marginally
resolved in our D array data.

7. 1998ApJS..114..177Z
Re:PKS 0048-09
PKS 0048-09.--This is a bright (m_V_ ~15 mag), strongly variable (up to 200%)
BL Lac object (Falomo et al. 1993, 1994). Optical spectroscopy by Falomo et al.
(1994) showed that there is no indication of spectral features either in
emission or absorption was found. A lower redshift limit of z>~0.2 can be
derived from the absence of the extended nebulosity of the BL Lac host galaxy
(Stickel, Fried, & Kuhr 1993). Observations of F172W, F150W, F220W, and F275W
all show a strong nuclear UV component, and not much else. The UV magnitudes
are 9.78, 9.40, 9.95, and 9.95, respectively.

8. 1998AJ....115.1295K
Re:[HB89] 0048-097
0048-097.--This source appears to contain very compact double-sided structure.

9. 1998A&A...336..479K
Re:PKS 0048-09
Our H-band photometry agrees well with previous studies (Table 6). High
resolution optical imaging by Falomo (1996) revealed a faint (m(R)~22.5)
companion object ~2.5" to the E of the BL Lac nucleus. The host galaxy
of PKS 0048-097 remained unresolved by Falomo (1996), but assuming an
elliptical host of M(R) = -23.5, he derived a lower limit to the
redshift of z>0.5. The host galaxy remains unresolved in the NIR. Some
hint of the eastern companion object is visible in NIR.

10. 1996MNRAS.283..241F
Re:[HB89] 0048-097
0048-097 This is a well-studied BL Lac object (see e.g. Falomo et al. 1988 and
references therein) belonging to the 1-Jy radio sample. No spectral features
have been reported in the optical spectra (Stickel et al. 1993; Falomo, Scarpa
& Bersanelli 1994) and the redshift remains unknown.
We obtained several images of this object, most of them with subarcsec
resolution. The best images of 1994 January show clearly the presence of a
faint (m_R_=22.5) close companion about 2.5 arcsec east of the BL Lac nucleus.
This feature is also visible on previous images and was first suggested in our
preliminary study of a number of BL Lacs (Falomo et al. 1990). This companion
was not detected by Stickel et al. (1993) but this may be the result of their
substantially lower resolution (1.3 as opposed to 0.8 arcsec). The companion
object appears resolved (see Fig. 1) and might be associated with the BL Lac
source.
The BL Lac object is unresolved and its radial brightness profile perfectly
matches that of the PSF (see Fig. 2). Assuming the host galaxy to be an
elliptical of M_R_ =-23.5, we set a lower limit to the redshift of z2>0.5.

11. 1994ApJS...93..125F
Re:[HB89] 0048-097
0048-097.-We obtained, over seven campaigns, 14 spectra of this bright
(m_V_ ~ 15) radio-selected source confirmed as a blazar by Angel &
Stockman (1980). No indication of spectral features either in emission or
absorption was found. The flux has shown variations as large as 200%. All
the spectra are well described by a power-law model from 4000 to 8000 A
even at minimum flux level. The spectral index shows variations of up to
0.8 correlating with flux variations in the sense that when the flux
increases the spectral index is flatter. The significance level is 95%
for a Spearman's test. However, the errors on {alpha} are quite large
and, if we consider that Ballard et al.(1990) found opposite results
(spectral index increases with flux), it is obvious that more accurate
observations are necessary to clarify the issue.

12. 1993AJ....106...11F
Re:[HB89] 0048-097
0048-097
This is a bright, strongly variable BL Lac object (Pica & Smith
1983). The m_V_ ~ 15 source is pointlike and no redshift determination
is yet available. Our 1987 January observations are ~50% brighter than
the four more recent ones. The spectral flux distribution is well
described by a simple power law of {alpha} ~ 1.0 [see Fig. 1(a)]. The
lowest observed flux level (1988 January) corresponds to a slightly
steeper ({DELTA}{alpha} ~ 0.2) spectral index.

13. 1993A&AS...98..393S
Re:MC3 0048-097
0048-097
Repeated spectroscopic observations failed to detect any emission or
absorption lines in this object. On the direct image, 0048-097 appears
stellar and there is no indication of the asymmetric elongation to the
east which has been seen by Falomo et al. (1990). A lower redshift limit
of z >~ 0.2 can be derived from the absence of the extended nebulosity of
the BL Lac host galaxy. A number of galaxies with 18 <~ m <~ 21 mag are
visible in the field. Although the two nearest neighbouring galaxies to
the west (G1) and south (G2) of the BL Lac object have somewhat similar
size and apparent magnitude, their redshifts are grossly different (see
Table 6).


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