ACDS V10.0 - Mon Apr 22 09:36:27 CEST 2019
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Detailed Description of VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
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Note : this is the description file of the original catalog.
This HTML page corresponds well to the original description, but some minor
changes in the format may have been introduced in the FITS output
files in order to allow for arithmetic operations on quantities
such as coordinates and times. h:m:s and d:m:s units are normally
converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the
units; the value given in the HTML files supersedes the value indicated in the ReadMe
file for this catalogue.
VIII/65 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
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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
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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:
FileName Lrecl Records Explanations
× 80 . This file
× ReadMe 80 . This file
× nvss.dat 158 1773484 The NVSS Catalog
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
Bytes Format Units Label Explanations
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
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.
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
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(End) Francois Ochsenbein [CDS] 24-Dec-2002