J/AJ/123/2402 The microJansky sky at 8.4GHz (Fomalont+, 2002)
The microJansky sky at 8.4 GHz.
Fomalont E.B., Kellermann K.I., Partridge R.B., Windhorst R.A.,
Richards E.A.
<Astron. J. 123, 2402 (2002)>
=2002AJ....123.2402F 2002AJ....123.2402F
ADC_Keywords: Galaxies, radio
Keywords: galaxies: active - galaxies: starburst - radio continuum
Abstract:
We present the results from two deep radio integrations at 8.4 GHz
using the Very Large Array. One of the fields, at 13h, +43° (SA 13
field), has an rms noise level of 1.49µJy and is the deepest radio
image yet made. Thirty-four sources in a complete sample were detected
above 7.5µJy, and 25 are optically identified to a limit of I=25.8,
using our deep Hubble Space Telescope and ground-based images. The
radio sources are usually located within 0.5" (typically 5kpc) of a
galaxy nucleus and generally have a diameter less than 2.5". We have
also analyzed a complete flux density-limited sample at 8.4GHz of 89
sources from five deep radio surveys, including the Hubble deep and
flanking fields, as well as the two new fields. Half of all the
optical counterparts are with galaxies brighter than I=23mag, but 20%
are fainter than I=25.5mag. There may be a small tendency for the
microJansky radio sources to prefer multigalaxy systems. The
distribution of the radio spectral index between 1.4 and 8.4GHz peaks
at α~-0.75 (S~ν+α) with a median value of -0.6. The
average spectral index becomes steeper (lower values) for sources
below 35µJy and for sources identified with optical counterparts
fainter than I=25.5mag. This correlation suggests that there is an
increasing contribution from starburst galaxies compared to AGNs at
lower radio flux densities and fainter optical counterparts. The
differential radio count between 7.5 and 1000µJy has a slope of
-2.11±0.13 and a surface density of 0.64 sources (arcmin)-2 with a
flux density greater than 7.5µJy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 106 50 SA13 source list and identifications
table2.dat 93 10 Hercules source list and identifications
table4.dat 45 89 Catalog of micro-Jansky sources at 8.4GHz
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Source New source identification (G1) (1)
4- 5 I2 --- [WFK95] ? Old identification number from Paper I,
Windhorst et al., 1995Natur.375..471W 1995Natur.375..471W
7 A1 --- f_[FKP2002] [*] Indicates not in the complete sample
8- 21 A14 --- [FKP2002] Source name (G1)
23- 27 F5.1 uJy S8.4GHz Total sky flux density at 8.4GHz (2)
29- 32 F4.1 uJy e_S8.4GHz Error in S8.4GHz (2)
34- 38 F5.1 --- SNR Signal-to-noise on the 6" resolution image
40 A1 --- l_Size Limit flag on Size
42- 44 F3.1 arcsec Size Deconvolved source angular size
46- 47 I2 h RAh Hour of Right Ascension (J2000)
49- 50 I2 min RAm Minute of Right Ascension (J2000)
52- 57 F6.3 s RAs Second of Right Ascension (J2000)
59- 62 F4.2 s e_RAs The RMS error on RAs
64 A1 --- DE- Sign of Declination (J2000)
65- 66 I2 deg DEd Degree of Declination (J2000)
68- 69 I2 arcmin DEm Arcminute of Declination (J2000)
71- 75 F5.2 arcsec DEs Arcsecond of Declination (J2000)
77- 80 F4.2 arcsec e_DEs The RMS error in DEs
82- 84 A3 --- IDType Optical identification type (G2)
86 A1 --- l_Bmag Limit flag on Bmag
88- 92 F5.2 mag Bmag ? The B band magnitude
93 A1 --- l_Vmag Limit flag on Vmag
95- 99 F5.2 mag Vmag ? The V band magnitude
100 A1 --- l_Imag Limit flag on Imag
102-106 F5.2 mag Imag The I band magnitude
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Note (1): Weaker radio sources which are coincident with an optical object
are labeled with a letter (a-h) and given at the end of the table.
Note (2): After correction for all instrumental and resolution effects
including the primary beam attenuation of the telescopes.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Source ? New source identification (G1)
4- 17 A14 --- [FKP2002] Source name (G1)
18 A1 --- f_[FKP2002] [*] Indicates not in the complete sample
20- 23 I4 uJy S8.4GHz Total sky flux density at 8.4GHz (1)
25- 26 I2 uJy e_S8.4GHz Error in S8.4GHz (1)
28- 31 F4.1 --- SNR Signal-to-noise on the 6" resolution image
33 A1 --- l_Size Limit flag on Size
34- 36 F3.1 arcsec Size Deconvolved source angular size
38- 39 I2 h RAh Hour of Right Ascension (J2000)
41- 42 I2 min RAm Minute of Right Ascension (J2000)
44- 49 F6.3 s RAs Second of Right Ascension (J2000)
51- 54 F4.2 s e_RAs The RMS error on RAs
56 A1 --- DE- Sign of Declination (J2000)
57- 58 I2 deg DEd Degree of Declination (J2000)
60- 61 I2 arcmin DEm Arcminute of Declination (J2000)
63- 67 F5.2 arcsec DEs Arcsecond of Declination (J2000)
69- 72 F4.2 arcsec e_DEs The RMS error in DEs
74-103 A30 --- Com Optical information (G2)
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Note (1): After correction for all instrumental and resolution effects
including the primary beam attenuation of the telescopes.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- [FKP2002] Source name (G1)
16 A1 --- n_[FKP2002] [*] Indicates source is resolved, >2.5''
18- 21 I4 uJy S8.4 Total sky flux density at 8.4 GHz
23 A1 --- l_Sp+Index Limit flag on Sp+Index
25- 28 F4.1 --- Sp+Index ? Spectral index
30- 32 A3 --- IDType Optical identification type (G2)
34 A1 --- l_Imag Limit flag on Imag
36- 39 F4.1 mag Imag ? The I band magnitude
41- 43 A3 --- Xray Detection of X-ray emission (1)
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Note (1): From the sources in the Hubble and SA13 fields (Brant et al.,
2001AJ....122....1B 2001AJ....122....1B, Mushotzky et al., 2000Natur.404..459M 2000Natur.404..459M).
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Global notes:
Note (G1): Nomenclature:
Table 1: <[FKP2002] SA 13 NN> = <[FKP2002] JHHMMSS+DDMMSS>
<[FKP2002] SA 13 a> = <[FKP2002] JHHMMSS+DDMMSS>
Table 2: <[FKP2002] Hercules NN> = <[FKP2002] JHHMMSS+DDMMSS>
Table 4: <[FKP2002] mJy BHHMMSS+DDMMSS>
<[FKP2002] mJy JHHMMSS+DDMMSS>
Note (G2): Optical identification type:
g = galaxy of unknown type
g/b = interacting galaxies. Magnitudes given for galaxy associated
with the radio source
Q = Quasar
g? = Uncertain identification with a faint object
EF = Empty field with magnitude limit given
ell = Elliptical galaxy
sp = Spiral galaxy
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History:
From electronic version of the journal + Erratum
References:
Windhorst et al., Paper I 1995Natur.375..471W 1995Natur.375..471W
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 17-Jun-2002