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J/A+AS/123/529 UV-excess quasar candidates around NGC 450 (Gosset+ 1997)
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Surveys of ultraviolet-excess quasar candidates in large fields.
The area around NGC 450
Gosset E., Moreau O., Surdej J.
<Astron. Astrophys. Suppl. Ser. 123, 529 (1997)>
=1997A&AS..123..529G (SIMBAD/NED BibCode)
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ADC_Keywords: QSOs ; Photometry, UBV ; Redshifts
Keywords: quasars: general - surveys
Abstract:
We describe the results of a survey for moderately bright quasars
performed in a 20.6-square-degree field around the galaxy NGC 450. The
quasar candidates we re-selected on the basis of their ultraviolet
excess: by comparative visual inspection of the double image of each
single object on a U/B dual-exposure Schmidt photographic plate, 95
primary and 45 secondary quasar candidates were selected on the basis
of their U image being too bright. The spectroscopic identification of
the primary candidates led to the discovery of 59 bona fide quasars
(out of which 6 were previously known). The Palomar Schmidt plate was
digitised using the MAMA measuring machine and the outcoming data
reduced using ad hoc procedures. A photometric calibration allowed us
to derive values for the limiting magnitudes and for the U-B index
selection threshold of the survey. A catalogue containing 60 quasars
is presented with accurate positions, magnitudes and additional
information such as redshifts. We studied the spatial distribution of
the objects and detected, for the quasars of our sample, a significant
deviation from randomness in the form of a propensity to cluster in
pairs on the celestial sphere with a typical scale of about 10arcmin.
We also formally detected a tendency towards a 3-D clustering, but
this result is induced by a single pair of quasars. A forthcoming
paper will deal with a similar work performed in a field around NGC
520; the latter field is located directly to the North of the present
one and slightly overlaps it.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 92 140 Catalogue of quasars and quasar candidates
notes.dat 106 38 Individual notes
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1 I1 h RAh Right ascension (J2000)
3- 4 I2 min RAm Right ascension (J2000)
6- 10 F5.2 s RAs Right ascension (J2000)
11 A1 --- u_RAs [:] ":" slightly less precise value
13 A1 --- DE- Declination sign
14 I1 deg DEd Declination (J2000)
16- 17 I2 arcmin DEm Declination (J2000)
19- 22 F4.1 arcsec DEs Declination (J2000)
23 A1 --- u_DEs [:] ":" slightly less precise value
24- 30 F7.5 --- z ? Redshift
31 A1 --- u_z [?:] ":" uncertain value
"?" very uncertain value
33- 42 A10 --- Name Object name (1)
44 A1 --- P/S [PS] Primary (P) or secondary (S) candidate
45 A1 --- n_P/S [*] * when the spectrum of the object is
available in fig.2 of the paper.
47 A1 --- --- [#]
48- 50 I3 --- NGC450 Internal identification number in the
present survey (NGC450 # "NGC450")
51 A1 --- n_NGC450 [*] Flag indicating a note in notes.dat file
53 A1 --- --- [#]
54- 56 I3 --- NGC520 ? Identification number in the NGC 520
survey (NGC520 # 'NGC520')
57 A1 --- m_NGC520 [B] Multiplicity index on NGC520
58 A1 --- l_Bmag Limit flag on Bmag
59- 63 F5.2 mag Bmag B magnitude
64 A1 --- u_Bmag Uncertainty flag on Bmag
66 A1 --- l_Umag Limit flag on Umag
67- 71 F5.2 mag Umag U magnitude
72 A1 --- u_Umag Uncertainty flag on Umag
74 A1 --- l_U-B Limit flag on U-B
75- 79 F5.2 mag U-B U-B colour index
80 A1 --- u_U-B Uncertainty flag on U-B
82- 92 A11 --- Spect Spectroscopy (2)
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Note (1): B1950 name of the quasar, or an indication of the nature of the
object (if it is not a quasar, e.G. STAR), or simply states that
the object is still an unidentified candidate (C).
Note (2): Identification of the spectroscopic runs with the exposure time in
seconds.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- NGC450 NGC450 internal designation
5-106 A102 --- Note Text of the note
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Acknowledgements: Eric Gosset <gosset@astro.ulg.ac.be>
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(End) Patricia Bauer [CDS] 02-Dec-1997