Information on Service 'High-Resolution Very Large Array Imaging of Sloan Digital Sky Survey Stripe 82 at 1.4 GHz'

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This is a high-resolution radio survey of the Sloan Digital Sky Survey (SDSS) Southern Equatorial Stripe, a.k.a. Stripe 82. This 1.4 GHz survey was conducted with the Very Large Array (VLA) primarily in the A-configuration, with supplemental B-configuration data to increase sensitivity to extended structure. The survey has an angular resolution of 1.''8 and achieves a median rms noise of 52 μJy per beam over 92 deg^2. The catalog contains 17,969 isolated radio components, for an overall source density of ∼195 sources/deg^2. See also J.A. Hodge et al, 2011AJ....142....3H .

For a list of all services and tables belonging to this service's resource, see Information on resource 'High-Resolution Very Large Array Imaging of Sloan Digital Sky Survey Stripe 82 at 1.4 GHz'

Overview

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This service is published as follows:

local means it is listed on our front page, ivo_managed means it has a record in the VO registry.

Input Fields

The following fields are available to provide input to the service (with some renderers, some of these fields may be unavailable):

NameTable Head DescriptionUnitUCD
DEC Delta (ICRS) Declination (ICRS decimal) deg pos.eq.dec
f_peak Peak Flux Peak flux density derived by fitting an elliptical Gaussian model to the source. The uncertainty is given in the rms_nose column. mJy/beam stat.max;phot.flux.density;em.radio.1500-3000MHz
hscs_pos Position/Name Coordinates (as h m s, d m s or decimal degrees), or SIMBAD-resolvable object N/A N/A
hscs_sr Search radius Search radius in arcminutes N/A N/A
imag m_i SDSS i-band magnitude of the closest match in SDSS DR6. mag phot.mag;em.opt.I
MAXREC Match limit Maximum number of records returned. Pass 0 to retrieve service parameters. N/A N/A
p_s P(S) Probability that the source is spurious (e.g., because of a sidelobe of a nearby bright source). N/A stat.likelihood;obs
RA Alpha (ICRS) Right Ascension (ICRS decimal) deg pos.eq.ra
RESPONSEFORMAT Output Format File format requested for output. N/A meta.code.mime
SR Search Radius Search radius deg N/A
VERB Verbosity Exhaustiveness of column selection. VERB=1 only returns the most important columns, VERB=2 selects the columns deemed useful to the average user, VERB=3 returns a table with all available columns. N/A N/A

Default Output Fields

The following fields are contained in the output by default. More fields may be available for selection; these would be given below in the VOTable output fields.

NameTable Head DescriptionUnitUCD
_r Dist. Distance to cone center deg pos.distance
c_sdss Cls SDSS morphological class of the closest match in SDSS DR6; s = stellar, g = nonstellar/galaxy. N/A src.morph.type
ct # Row count; this is not part of the original table but was added to satisfy SCS requirements. N/A meta.id;meta.main
d_sdss d(SDSS) Separation of the closest match in SDSS DR6. deg pos.angDistance;meta.id.cross
dej2000 Dec Declination, J2000 Note p deg pos.eq.dec;meta.main
f_int Int. flux Integrated flux density in mJy derived from the elliptical Gaussian model fit. Note f mJy phot.flux.density;em.radio.1500-3000MHz
f_peak Peak Flux Peak flux density derived by fitting an elliptical Gaussian model to the source. The uncertainty is given in the rms_nose column. mJy/beam stat.max;phot.flux.density;em.radio.1500-3000MHz
field Field The field name is the name of the coadded image containing the source. Note that the field name encodes the center of the field; field hhmmm+ddmmm is centered at RA = hh mm.m, Dec = +dd mm.m. The letter appended to the field name indicates the last catalog release in which the image was modified. N/A obs.field
imag m_i SDSS i-band magnitude of the closest match in SDSS DR6. mag phot.mag;em.opt.I
n_sdss |SDSS| Number of matching SDSS DR6 objects within 8 arcsec. N/A meta.number;meta.id.cross
p_s P(S) Probability that the source is spurious (e.g., because of a sidelobe of a nearby bright source). Note s N/A stat.likelihood;obs
pa PA Position angle of the elliptical Gaussian model for the source after beam deconvolution, east of north. deg pos.posAng;meta.modelled
pa_raw PA raw Position angle of the elliptical Gaussian model for the source before beam deconvolution, east of north. deg pos.posAng
raj2000 RA Right Ascension, J2000 Note p deg pos.eq.ra;meta.main
rms_noise RMS noise Local noise estimate at the source position, calculated by combining the measured noise from all grid images contributing to the coadded map at the source position. mJy stat.error;phot.flux.density
smaj_ax Semimajor FWHM semimajor axis of the elliptical Gaussian model for the source after beam deconvolution. This is zero when the fitted value prior to deconvolution to is smaller than the beam (1.8'') due to noise. deg phys.angSize.smajAxis,meta.modelled
smaj_ax_raw Smaj raw FWHM semimajor axis of the elliptical Gaussian model before beam deconvolution. deg phys.angSize.smajAxis
smin_ax Semiminor FWHM semiminor axis of the elliptical Gaussian model for the source after beam deconvolution. This is zero when the fitted value prior to deconvolution to is smaller than the beam due to noise. deg phys.angSize.sminAxis;meta.modelled
smin_ax_raw Smin raw FWHM semiminor axis of the elliptical Gaussian model before beam deconvolution. deg phys.angSize.sminAxis

VOTable Output Fields

The following fields are available in VOTable output. The verbosity level is a number intended to represent the relative importance of the field on a scale of 1 to 30. The services take a VERB argument. A field is included in the output if their verbosity level is less or equal VERB*10.

NameTable Head DescriptionUnitUCD Verb. Level
raj2000 RA Right Ascension, J2000 Note p deg pos.eq.ra;meta.main 1
dej2000 Dec Declination, J2000 Note p deg pos.eq.dec;meta.main 1
ct # Row count; this is not part of the original table but was added to satisfy SCS requirements. N/A meta.id;meta.main 1
f_peak Peak Flux Peak flux density derived by fitting an elliptical Gaussian model to the source. The uncertainty is given in the rms_nose column. mJy/beam stat.max;phot.flux.density;em.radio.1500-3000MHz 5
f_int Int. flux Integrated flux density in mJy derived from the elliptical Gaussian model fit. Note f mJy phot.flux.density;em.radio.1500-3000MHz 5
_r Dist. Distance to cone center deg pos.distance 10
p_s P(S) Probability that the source is spurious (e.g., because of a sidelobe of a nearby bright source). Note s N/A stat.likelihood;obs 15
rms_noise RMS noise Local noise estimate at the source position, calculated by combining the measured noise from all grid images contributing to the coadded map at the source position. mJy stat.error;phot.flux.density 15
smaj_ax Semimajor FWHM semimajor axis of the elliptical Gaussian model for the source after beam deconvolution. This is zero when the fitted value prior to deconvolution to is smaller than the beam (1.8'') due to noise. deg phys.angSize.smajAxis,meta.modelled 15
smin_ax Semiminor FWHM semiminor axis of the elliptical Gaussian model for the source after beam deconvolution. This is zero when the fitted value prior to deconvolution to is smaller than the beam due to noise. deg phys.angSize.sminAxis;meta.modelled 15
pa PA Position angle of the elliptical Gaussian model for the source after beam deconvolution, east of north. deg pos.posAng;meta.modelled 15
smaj_ax_raw Smaj raw FWHM semimajor axis of the elliptical Gaussian model before beam deconvolution. deg phys.angSize.smajAxis 15
smin_ax_raw Smin raw FWHM semiminor axis of the elliptical Gaussian model before beam deconvolution. deg phys.angSize.sminAxis 15
pa_raw PA raw Position angle of the elliptical Gaussian model for the source before beam deconvolution, east of north. deg pos.posAng 15
field Field The field name is the name of the coadded image containing the source. Note that the field name encodes the center of the field; field hhmmm+ddmmm is centered at RA = hh mm.m, Dec = +dd mm.m. The letter appended to the field name indicates the last catalog release in which the image was modified. N/A obs.field 15
n_sdss |SDSS| Number of matching SDSS DR6 objects within 8 arcsec. N/A meta.number;meta.id.cross 15
d_sdss d(SDSS) Separation of the closest match in SDSS DR6. deg pos.angDistance;meta.id.cross 15
imag m_i SDSS i-band magnitude of the closest match in SDSS DR6. mag phot.mag;em.opt.I 15
c_sdss Cls SDSS morphological class of the closest match in SDSS DR6; s = stellar, g = nonstellar/galaxy. N/A src.morph.type 15

VOResource XML (that's something exclusively for VO nerds)

Note f

The uncertainty in f_int can be considerably greater than that of f_peak depending on source size and morphology. An expression to estimate the uncertainty can be found in 2004AJ....128.1974S For point sources, the relative uncertainty reduces to: sigma_I/I = sqrt{ 2.5 sigma^2/I^2 + 0.01^2 }.

Note p

The positional errors are a function of source brightness, size, and noise in the map. They are best found using a simple rule-of-thumb approach, as the HAPPY-derived errors tend to be underestimated. An empirical equation for the accuracy at 90% confidence is f_Size * (1/SNR + 1/20), where f_Size is the fitted semimajor or semiminor axis size, and SNR is the signal to noise ratio 1997ApJ...475..479W. Systematic errors are smaller than 0.05".

Note s

P(S) values are computed using a custom algorithm based on multiple voting oblique decision tree classifiers, which were trained on deep VLA fields. Note that the algorithm is optimized for the FIRST survey, whereas the RMS computation for this catalog has changed significantly. The values of P(S) are therefore not very reliable for this catalog.