VIII/65 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
The NRAO VLA Sky Survey
Condon J.J., Cotton W.D., Greisen E.W., Yin Q.F., Perley R.A.,
Taylor G.B., Broderick J.J.
<Astron. J. 115, 1693 (1998)>
=1998AJ....115.1693C 1998AJ....115.1693C
ADC_Keywords: Radio sources ; Radio continuum ; Surveys
Description:
The NRAO VLA Sky Survey (NVSS) is a radio continuum survey covering
the sky north of -40° declination at 1.4GHz. The principal data
products of the NVSS are a set of 2326 4x4° continuum "cubes" with
three planes containing Stokes I, Q, and U images, plus a catalog of
almost 2 million discrete sources stronger than a flux density of
about 2.5mJy.
The images all have 45 arcsecond FWHM angular resolution and nearly
uniform sensitivity. Their rms brightness fluctuations are
approximately 0.45mJy/beam=0.14K (Stokes I) and 0.29mJy/beam=0.09K
(Stokes Q and U). The rms uncertainties in right ascension and
declination vary from ≤ ∼1arcsecond for the 400,000 sources stronger
than 15mJy to 7arcseconds at the survey limit.
A more detailed description is provided in the printed paper and at the
NVSS website at http://www.cv.nrao.edu/nvss/
where all data products, user software, and updates were released as
soon as they were produced and verified.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
nvss.dat 158 1773484 The NVSS Catalog
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See also:
VIII/59 : the FIRST Survey, version 1999Jul (White+ 1999)
http://www.cv.nrao.edu/nvss/ : the NVSS Home Page
Byte-by-byte Description of file: nvss.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Field Name of the original survey image field
from which the component was derived.
10- 16 F7.2 pix Xpos X position (RA direction) of the radio source
18- 24 F7.2 pix Ypos Y position (Dec direction) of the radio source
26- 39 A14 --- NVSS Source name (1)
41- 42 I2 h RAh Right Ascension J2000 (hours) (2)
44- 45 I2 min RAm Right Ascension J2000 (minutes) (2)
47- 51 F5.2 s RAs [0,60] Right Ascension J2000 (seconds) (2)
53 A1 --- DE- Declination J2000 (sign) (2)
54- 55 I2 deg DEd Declination J2000 (degrees) (2)
57- 58 I2 arcmin DEm Declination J2000 (minutes) (2)
60- 63 F4.1 arcsec DEs [0,60] Declination J2000 (seconds) (2)
65- 69 F5.2 s e_RAs Mean error on RA
71- 74 F4.1 arcsec e_DEs Mean error on Dec
76- 83 F8.1 mJy S1.4 Integrated 1.4GHz flux density of radio source
85- 91 F7.1 mJy e_S1.4 Mean error on S1.4
93 A1 --- l_MajAxis Limit flag on MajAxis
94- 98 F5.1 arcsec MajAxis Fitted (deconvolved) major axis of radio source
100 A1 --- l_MinAxis Limit flag on MinAxis
101-105 F5.1 arcsec MinAxis Fitted (deconvolved) minor axis of radio source
107-111 F5.1 deg PA [-90, 90]? Position angle of fitted major axis
113-116 F4.1 arcsec e_MajAxis ? Mean error on MajAxis
118-121 F4.1 arcsec e_MinAxis ? Mean error on MinAxis
123-126 F4.1 deg e_PA ? Mean error on PA
128-129 A2 --- f_resFlux [PS* ] Residual Code (3)
131-134 I4 mJy resFlux ? Peak residual flux, in mJy/beam (3)
136-141 F6.2 mJy polFlux ? Integrated linearly polarized flux density
143-147 F5.1 deg polPA *[-90,90]? The position angle of polFlux (4)
149-153 F5.2 mJy e_polFlux ? Mean error on polFlux
155-158 F4.1 deg e_polPA ? Mean error on polPA
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Note (1):
The NVSS Catalog designation is of the form
NVSS JHHMMSS+DDMMSS
using the standard IAU nomenclature prescription, where NVSS is the
catalog acronym, J specifies the coordinate equinox (for J2000)
HHMMSS are the hours, minutes, and truncated (not rounded) seconds of
right ascension, + or - is the sign of the declination, and DDMMSS are
the degrees, arcminutes, and truncated (not rounded) arcseconds of
declination. Thus, the NVSS source at equinox J2000.0 coordinates of
00h00m00.24s -20d04'49.1" is called NVSS J000000-200449. This name,
without the leading "NVSS J" prefix, is reported in the NVSS column.
There are four cases where a suffix "a" or "b" have been appended to
the name to ensure the naming unicity.
Note (2): Position of the centroid of the fitted radio source,
for the epoch of observation (1995±2).
Note (3): High residual values generally indicate complex sources.
f_resFlux contains a flag indicating a residual of the fit to the
radio source, which can be:
P: if the peak flux density residual was high
S: if the integrated flux density residual was high
Note (4):
polPA is the position angle (N through East) of the "E" vector of the
linear polarization if the source was detected (1 sigma) in linear
polarization.
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History:
The file "nvss.dat" was created from the ascii edition of NVSS as file
ftp://ftp.cv.nrao.edu/nvss/CATALOG/NVSSCatalog.text.gz (27-Sep-2002),
provided by the NVSS Catalog's authors.
Many of the descriptions enclosed in this ReadMe file were prepared
by the HEASARC team at
http://heasarc.gsfc.nasa.gov/W3Browse/all/nvss.html
(End) Francois Ochsenbein [CDS] 24-Dec-2002