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PG - PG Catalog of UV-excess objects |
HEASARC Archive |
Of the 1874 objects in the catalog as published in 1986 (1878 in this version), 1715 comprise a statistically complete sample covering 10714 square degrees from 266 fields taken on the Palomar 18-inch Schmidt telescope. Limiting magnitudes vary from field to field, ranging from 15.49 to 16.67. The overall completeness is estimated to be 84%, but that figure and the relative contributions of magnitude, color, and accidental errors vary depending on the magnitude and color distribution of the spectroscopic subsample.
The dominant population in this catalog is that of the hot, hydrogen-atmosphere subdwarfs, the sdB stars, which comprise nearly 40 per cent of the sample. The hot white dwarfs of spectral types DA, DB, and DO account for 21, 2.8, and 1.0 per cent of the sample, respectively, while cooler DC or DZ white dwarfs add another 1.2 per cent. Cataclysmic variables and composite-spectrum binaries account for 5 per cent, although many other spectra dominated by a hot star showed evidence for a cool companion at red wavelengths. Planetary nebulae central stars account for another 0.5 per cent. Extragalactic objects comprise about 9 per cent of the complete sample, with QSOs representing 5.4 per cent. Only 0.3 per cent (6 objects) remain with totally unsatisfactory or unknown spectral classes. (Notice that all of these percentage estimates are based on the published version of this catalog, and that the values in the current online version may be slightly different, as the latter includes a small number of updates and additions).
Name
This parameter was not given in the original published tabular version
(Table 5 of Green et al. 1986), but did appear in the finding charts.
It was constructed in the standard way, based on the IAU nomenclature
convention, using the prefix PG and the 1950 RA and Dec sexagesimal
coordinates for each entry. For example, the PG object at RA(1950) = 00 00
02.3 and Dec(1950) = +17 10 47 has the name of PG 0000+171.
RA
The right ascension of the object in the selected equinox. The
estimated accuracy of this coordinate is about 8 arc seconds.
Dec
The declination of the object in the selected equinox. The
estimated accuracy of this coordinate is about 8 arc seconds.
LII
The galactic longitude of the object.
BII
The galactic latitude of the object.
Pmag
The photographic B-magnitude of the object, with an estimated
accuracy of 0.29 magnitudes. If the object was found in overlapping fields,
the object magnitude (and limiting magnitude) from the the deeper exposure
was selected.
Blim
The limiting B-magnitude for the field in which this object was
discovered. If the object was found in overlapping fields, the limiting
magnitude (and object magnitude) from the the deeper exposure was selected.
A value of 0. for this parameter means that the object is not part of
the complete statistical sample, which can be due to faintness, or
nondetection in the automated scanning process, or its being in a field with
an abnormally bright limiting magnitude.
Comments
This parameter contains redshifts for extragalactic sources,
spectral types for companions to the blue stars, and/or brief notes
about any spectral peculiarities or uncertainties. It contains also
cross-identifications of the objects. Notice that the cross-identification
of PG 1535+547 with a Zwicky Catalog object has been changed from
I Zw 120 to I Zw 121. For complete cross-referencing on white dwarfs, see
the McCook & Sion White Dwarf Catalog (1984), ADC/CDS Catalog <III/129>.
Lists of previously identified ultraviolet-excess objects include:
PHL (Palomar-Haro-Luyten, 1962BITon...3...37H), ADC/CDS catalog <III/74> EG = Eggen and Greenstein (1965ApJ...141...83E, 1967ApJ...150..927E) T = Tonantzintla lists (1957BOTT....2G...3I, 1959BOTT....2I...3C) U = Usher and collaborators (1981ApJS...46..117U, 1982ApJS...48...51U, 1982ApJS...49...27U, 1984ApJS...56..393H) K = Kiso UV survey PB = Palomar-Berger (1977A&AS...28..123B) L,LB = Luyten lists (Univ. Minnesota) G,GD = Giclas Proper Motion Survey (see cats. <I/79>, <I/112>) F = Feige (1958ApJ...128..267F) HZ = Humason-Zwicky (1947ApJ...105...85H) C,CB = Pesch & Sandyuleak (1983ApJS...51..171P, 1984ApJS...55..517S)
Pg_Class
A spectral classification full details of which are given in
Section IV of the published version of this catalog. A colon in this field
denotes uncertainty. The various categories are as follows:
HBB = Horizontal-branch B star SDB = Subdwarf B (sdB) star SDB-O = Subdwarf B star with a suggestion of He I 4471 A in absorption SD = Presumed subdwarf but spectrum had low signal-to-noise SDOA = Subdwarf star with dominant H and pronounced He 4471 absorption SDOB = Subdwarf star with dominant He and (generally) H absorption SDOC = Hottest type of sdO star with dominant He II absorption SDOD = Cooler subdwarf with "pure" He I absorption spectrum SDO = Subdwarf O (sdO) star DA+ = White dwarf of the DA type, where + is the temperature subtype DB+ = White dwarf of the DB type, where + is the temperature subtype DAO = White dwarf with an atmosphere of mixed H and He composition DAB = White dwarf with an atmosphere of mixed H and He composition DBA = White dwarf with an atmosphere of mixed H and He composition DO = White dwarf with spectrum dominated by He II absorption 1159 = Member of the PG 1159-035 spectroscopic class DC = White dwarf of the DC type DZ = White dwarf of the DZ type PNN = Planetary Nebula Nucleus CV = Presumed galactic cataclysmic variable BIN = Composite spectrum object thought to be non-interacting binary DME = M dwarf emission line star probably observed during flare QSO = Broad emision line object with absolute B mag brighter than -23 SEY = Broad emision line object with absolute B mag fainter than -23 GAL = Galaxy with UV excess and (in most cases) sharp emission lines BLL = BL Lacertae-type oject ?? = Object of unknown type
Spect_Note
A flag that is set to "Y" if there was at least one follow-up
spectrum obtained at higher dispersion than the original Palomar spectrum.
Bmag
Photoelectric Johnson B magnitude.
Bmag_Flag
A colon in this field denotes uncertainty.
UB_Color
Photoelectric Johnson (U-B) color index.
UB_Color_Flag
A colon in this field denotes uncertainty.
BV_Color
Photoelectric Johnson (B-V) color index.
Pal_Vmag
The Palomar 5m multichannel spectrophotometric v magnitude.
This is one of four "monochromatic" bands defined by Greenstein (1976, ApJ,
207, L119) centered at 2.80 inverse microns (um-1) for u, 2.12 um-1 for g,
1.85 um-1 for v, and 1.44 um-1 for r, and calibrated in the
"AB79" system by Oke & Gunn (1983, ApJ, 266, 713).
Pal_Vmag_Flag
A colon in this field denotes uncertainty.
Pal_Uv_Color
The Palomar 5m multichannel spectrophotometric (u-v) index.
This system is based on 4 "monochromatic" bands defined by Greenstein (1976,
ApJ, 207, L119) centered at 2.80 inverse microns (um-1) for u, 2.12 um-1
for g, 1.85 um-1 for v, and 1.44 um-1 for r, and calibrated in the
"AB79" system by Oke & Gunn (1983, ApJ, 266, 713).
Pal_Uv_Color_Flag
A colon in this field denotes uncertainty.
Pal_BV_Color
The Palomar 5m multichannel spectrophotometric (b-v) index.
This system is based on 4 "monochromatic" bands defined by Greenstein (1976,
ApJ, 207, L119) centered at 2.80 inverse microns (um-1) for u, 2.12 um-1
for g, 1.85 um-1 for v, and 1.44 um-1 for r, and calibrated in the
"AB79" system by Oke & Gunn (1983, ApJ, 266, 713).
Pal_GR_Color
The Palomar 5m multichannel spectrophotometric (g-r) index.
This system is based on 4 "monochromatic" bands defined by Greenstein (1976,
ApJ, 207, L119) centered at 2.80 inverse microns (um-1) for u, 2.12 um-1
for g, 1.85 um-1 for v, and 1.44 um-1 for r, and calibrated in the
"AB79" system by Oke & Gunn (1983, ApJ, 266, 713).
Strom_Vmag
The V magnitude in the Stromgren (Stroemgren) system.
Strom_BY_Color
The (b-y) color index in the Stromgren (Stroemgren) system.
Strom_BY_Color_Flag
A colon in this field denotes uncertainty.
Strom_UB_Color
The (u-b) color index in the Stromgren (Stroemgren) system.
Strom_UB_Color_Flag
A colon in this field denotes uncertainty.
Strom_M1_Index
The m1 index in the Stromgren (Stroemgren) system.
Reference
References for the photoelectric photometry and studies of
individual objects. Additional broad-band photometry was quoted from Eggen
(1968, ApJS< 16, 97). Most of the values without citations are based on
the authors' measurements. Those with numbers refer to the following papers:
1 = Green =1980ApJ...238..685G 2 = Graham =1972AJ.....77..144G 3 = Greenstein =1984ApJ...276..602G 4 = Wegner =1983AJ.....88..109W 5 = Liebert & Stockman =1980PASP...92..657L 6 = Wesemael et al. =1985ApJS...58..379W 7 = Bond et al. =1984ApJ...279..751B 8 = Ferguson et al. =1981ApJ...251..205F 9 = Margon et al. =1981Natur.293..200M 10 = Ferguson et al. =1984ApJ...287..320F 11 = Green et al. =1982PASP...94..560G 12 = Becker et al. =1982MNRAS.201..265B 13 = Penning et al. =1984ApJ...276..233P 14 = Liebert et al. =1982ApJ...256..594L 15 = Liebert et al. =1984ApJ...277..692L 16 = Liebert et al. =1983ApJ...264..262L 17 = Barker & Cudworth =1984ApJ...278..610B 18 = Schmidt & Green =1983ApJ...269..352S 19 = Weymann et al. =1980Natur.285...64W 20 = Ellis et al. =1984PASP...96..283E 21 = Sion et al. =1985ApJ...292..477S 22 = Sion et al. =1985ApJ...292..471S 23 = Szkody et al. =1985ApJ...293..321S 24 = McGraw et al. =1979IAUCo..53..377M 25 = Winget et al. =1984IAUC.3932.....W 26 = Winget et al. =1984ApJ...279L..15W 27 = Nather et al. =1984IAUC.4021.....N 28 = Green =1976PASP...88..665G
Class
The HEASARC browse classification for the object, constructed
from its PG classification (pg_class).