Information on Service 'LoTSS DR2 Rotation Measures'

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The LOFAR Two Meter Sky Survey LoTSS DR2 (2022A&A...659A...1S) obtained radio data from 27% of the northern sky between 120 and 168 MHz in the year 2014 through 2020. This service publishes polarization spectra of extragalactic radio sources (radio galaxies and blazars) and the rotation measures derived from them. We also give redshifts for all sources. The data has a spatial resolution of 20 arcsec.

For a list of all services and tables belonging to this service's resource, see Information on resource ' Rotation Measures from the LOFAR Two Meter Sky Survey LoTSS DR2'

Overview

You can access this service using:

Coverage

4.9628e-07 6.94792e-07 eV

2014.4 2020.09

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.

Other services provided on the underlying data include:

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
epoch_mjd Epoch_mjd Median epoch of observation d time.epoch
field LoTSS pointing LoTSS observation pointing name N/A meta.id;obs.field
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
maxrec Match limit Maximum number of records returned. Pass 0 to retrieve service parameters. N/A N/A
RA Alpha (ICRS) Right Ascension (ICRS decimal) deg pos.eq.ra
responseformat Output Format File format requested for output. N/A meta.code.mime
rm Rot. Meas. Rotation measure rad.m**-2 phys.polarization.rotMeasure;meta.main
source_name_dr2 ILT name Official source name assigned by the International LOFAR Telescope ILT. N/A meta.id
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
beam_maj Beam_maj Beam major axis deg pos.angResolution;instr.beam;phys.angSize.smajAxis
beam_min Beam_min Beam minor axis deg pos.angResolution;instr.beam;phys.angSize.sminAxis
beam_pa Beam_pa Beam position angle deg pos.angResolution;instr.beam;pos.posAng
cat_id Cat. # Source ID in catalog N/A meta.id;meta.main
complex_flag Complex_flag Faraday complexity flag N/A meta.code
datalink Spectrum Datalink for the spectrum N/A meta.ref.url
dataref Dataref Data references N/A meta.bib.bibcode
dec Dec Declination [ICRS] of the polarised emission at epoch (this will often be an one extremity of the radio source). deg pos.eq.dec;meta.main
dec_dr2 Dec_dr2 LoTSS DR2 Dec of the centroid of the total radio intensity using pyBDSF. deg pos.eq.dec
dec_nvss Dec_nvss Dec of the object in NVSS deg pos.eq.dec
e_dec_dr2 E_dec_dr2 Error in dec_dr2 deg stat.error;pos.eq.dec
e_ra_dr2 E_ra_dr2 Error in ra_dr2 deg stat.error;pos.eq.ra
e_total_flux_dr2 E_total_flux_dr2 Error in total_flux_dr2 Jy stat.error;phot.flux;em.radio
epoch_mjd Epoch_mjd Median epoch of observation d time.epoch
field LoTSS pointing LoTSS observation pointing name N/A meta.id;obs.field
fracpol Fracpol Fractional (linear) polarization N/A phys.polarization.linear
fracpol_err Fracpol_err Error in fractional polarization N/A stat.error;phys.polarization.linear
grm Grm Average Galactic RM within an aperture of radius 1 degree from the Garching Faraday rotation sky v2. Note galm rad.m**-2 phys.polarization.rotMeasure
l144 L144 Spectral luminosity at 144 MHz in the rest frame of the source W.Hz**-1 phys.luminosity
linearsize_kpc Linearsize_kpc Projected largest linear size kpc phys.size
maj_dr2 Maj_dr2 Semimajor axis of the radio emission arcsec phys.angSize.smajAxis
maxfreq Maxfreq Highest frequency Hz em.freq;stat.max
min_dr2 Min_dr2 Semiminor axis of the radio emission arcsec phys.angSize.sminAxis
minfreq Minfreq Lowest frequency Hz em.freq;stat.min
nchan Nchan Number of channels used in RM derivation N/A meta.number;em.bin
noise_chan Noise_chan Typical per-channel noise in Q;U Jy stat.error;instr.det.noise
notes Notes Notes N/A meta.note
nvss_rm Nvss_rm Rotation measure of the object in NVSS rad.m**-2 phys.polarization.rotMeasure
pa_dr2 Pa_dr2 Position angle of the radio emission, north over west deg pos.posAng
phot_spec_z_best Phot_spec_z_best Nature of z_best: 0: phot, 1: spec N/A meta.code;src.redshift
polint Pol. intens. Polarized intensity Jy phot.flux.density;phys.polarization.linear
polint_err Err. Pol.Int. Error in Polarised Intensity Jy stat.error;phot.flux.density;phys.polarization.linear
pos_err Pos_err Position uncertainty deg stat.error;pos
ra RA Right Ascension [ICRS] of the polarised emission at epoch (this will often be an one extremity of the radio source). deg pos.eq.ra;meta.main
ra_dr2 Ra_dr2 LoTSS DR2 RA of the centroid of the total radio intensity using pyBDSF. deg pos.eq.ra
ra_nvss Ra_nvss RA of the object in NVSS deg pos.eq.ra
reffreq_beam Reffreq_beam Reference frequency for beam Hz em.freq;instr.beam
reffreq_i Reffreq_i Reference frequency for Stokes I Hz em.freq;phys.polarization.stokes.I
reffreq_pol Reffreq_pol Reference frequency for polarization Hz em.freq;phys.polarization
rm Rot. Meas. Rotation measure rad.m**-2 phys.polarization.rotMeasure;meta.main
rm_err Err. RM Total error in RM rad.m**-2 stat.error;phys.polarization.rotMeasure
rmsf_fwhm Rmsf_fwhm Full-width at half maximum of the RMSF rad.m**-2 instr.rmsf;stat.fwhm
rrm Rrm The residual RM after subtraction of the average Galactic RM within an aperture of radius 1 degree (see the grm column). Note galm rad.m**-2 phys.polarization.rotMeasure;src.net
source_name_dr2 ILT name Official source name assigned by the International LOFAR Telescope ILT. N/A meta.id
total_flux_dr2 Total_flux_dr2 Total radio flux at 144 MHz from pyBDSF. Jy phot.flux;em.radio
x X x-pixel coordinate within an individual LoTSS field, ranging from 0 to 3200, for a pixel width of 4.5 arcsec pixel pos.cartesian.x;instr.det
y Y y-pixel coordinate within an individual LoTSS field, ranging from 0 to 3200, for a pixel height of 4.5 arcsec pixel pos.cartesian.y;instr.det
z_best Z_best Best redshift available from the literature, typically from NED. N/A src.redshift
zphot Zphot Photometric redshift derived here from archive photometry (WISE, PanSTARRS, etc; cf. 2021A&A...648A...4D). N/A src.redshift.phot
zphot_err Zphot_err Error in zphot N/A stat.error;src.redshift.phot

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
cat_id Cat. # Source ID in catalog N/A meta.id;meta.main 1
ra RA Right Ascension [ICRS] of the polarised emission at epoch (this will often be an one extremity of the radio source). deg pos.eq.ra;meta.main 1
dec Dec Declination [ICRS] of the polarised emission at epoch (this will often be an one extremity of the radio source). deg pos.eq.dec;meta.main 1
datalink Spectrum Datalink for the spectrum N/A meta.ref.url 1
rm Rot. Meas. Rotation measure rad.m**-2 phys.polarization.rotMeasure;meta.main 1
polint Pol. intens. Polarized intensity Jy phot.flux.density;phys.polarization.linear 1
fracpol Fracpol Fractional (linear) polarization N/A phys.polarization.linear 1
minfreq Minfreq Lowest frequency Hz em.freq;stat.min 1
maxfreq Maxfreq Highest frequency Hz em.freq;stat.max 1
epoch_mjd Epoch_mjd Median epoch of observation d time.epoch 1
field LoTSS pointing LoTSS observation pointing name N/A meta.id;obs.field 1
z_best Z_best Best redshift available from the literature, typically from NED. N/A src.redshift 1
source_name_dr2 ILT name Official source name assigned by the International LOFAR Telescope ILT. N/A meta.id 1
ra_dr2 Ra_dr2 LoTSS DR2 RA of the centroid of the total radio intensity using pyBDSF. deg pos.eq.ra 1
dec_dr2 Dec_dr2 LoTSS DR2 Dec of the centroid of the total radio intensity using pyBDSF. deg pos.eq.dec 1
total_flux_dr2 Total_flux_dr2 Total radio flux at 144 MHz from pyBDSF. Jy phot.flux;em.radio 1
zphot Zphot Photometric redshift derived here from archive photometry (WISE, PanSTARRS, etc; cf. 2021A&A...648A...4D). N/A src.redshift.phot 5
_r Dist. Distance to cone center deg pos.distance 10
phot_spec_z_best Phot_spec_z_best Nature of z_best: 0: phot, 1: spec N/A meta.code;src.redshift 10
rm_err Err. RM Total error in RM rad.m**-2 stat.error;phys.polarization.rotMeasure 15
polint_err Err. Pol.Int. Error in Polarised Intensity Jy stat.error;phot.flux.density;phys.polarization.linear 15
fracpol_err Fracpol_err Error in fractional polarization N/A stat.error;phys.polarization.linear 15
rmsf_fwhm Rmsf_fwhm Full-width at half maximum of the RMSF rad.m**-2 instr.rmsf;stat.fwhm 15
reffreq_pol Reffreq_pol Reference frequency for polarization Hz em.freq;phys.polarization 15
pos_err Pos_err Position uncertainty deg stat.error;pos 15
complex_flag Complex_flag Faraday complexity flag N/A meta.code 15
beam_maj Beam_maj Beam major axis deg pos.angResolution;instr.beam;phys.angSize.smajAxis 15
beam_min Beam_min Beam minor axis deg pos.angResolution;instr.beam;phys.angSize.sminAxis 15
beam_pa Beam_pa Beam position angle deg pos.angResolution;instr.beam;pos.posAng 15
reffreq_beam Reffreq_beam Reference frequency for beam Hz em.freq;instr.beam 15
noise_chan Noise_chan Typical per-channel noise in Q;U Jy stat.error;instr.det.noise 15
dataref Dataref Data references N/A meta.bib.bibcode 15
notes Notes Notes N/A meta.note 15
reffreq_i Reffreq_i Reference frequency for Stokes I Hz em.freq;phys.polarization.stokes.I 15
zphot_err Zphot_err Error in zphot N/A stat.error;src.redshift.phot 15
nchan Nchan Number of channels used in RM derivation N/A meta.number;em.bin 15
e_ra_dr2 E_ra_dr2 Error in ra_dr2 deg stat.error;pos.eq.ra 15
e_dec_dr2 E_dec_dr2 Error in dec_dr2 deg stat.error;pos.eq.dec 15
e_total_flux_dr2 E_total_flux_dr2 Error in total_flux_dr2 Jy stat.error;phot.flux;em.radio 15
maj_dr2 Maj_dr2 Semimajor axis of the radio emission arcsec phys.angSize.smajAxis 15
min_dr2 Min_dr2 Semiminor axis of the radio emission arcsec phys.angSize.sminAxis 15
pa_dr2 Pa_dr2 Position angle of the radio emission, north over west deg pos.posAng 15
l144 L144 Spectral luminosity at 144 MHz in the rest frame of the source W.Hz**-1 phys.luminosity 15
linearsize_kpc Linearsize_kpc Projected largest linear size kpc phys.size 15
rrm Rrm The residual RM after subtraction of the average Galactic RM within an aperture of radius 1 degree (see the grm column). Note galm rad.m**-2 phys.polarization.rotMeasure;src.net 15
grm Grm Average Galactic RM within an aperture of radius 1 degree from the Garching Faraday rotation sky v2. Note galm rad.m**-2 phys.polarization.rotMeasure 15
x X x-pixel coordinate within an individual LoTSS field, ranging from 0 to 3200, for a pixel width of 4.5 arcsec pixel pos.cartesian.x;instr.det 20
y Y y-pixel coordinate within an individual LoTSS field, ranging from 0 to 3200, for a pixel height of 4.5 arcsec pixel pos.cartesian.y;instr.det 20
ra_nvss Ra_nvss RA of the object in NVSS deg pos.eq.ra 20
dec_nvss Dec_nvss Dec of the object in NVSS deg pos.eq.dec 20
nvss_rm Nvss_rm Rotation measure of the object in NVSS rad.m**-2 phys.polarization.rotMeasure 20
rm_err_snr Rm_err_snr Error in RM from signal to noise ratio only rad.m**-2 stat.error;phys.polarization.rotMeasure 25
l L Galactic Longitude deg pos.galactic.lon 25
b B Galactic Latitude deg pos.galactic.lat 25
beamdist Beamdist Distance from beam centre (taken as centre of tile) deg pos.angDistance;instr.beam 25
complex_test Complex_test Faraday complexity metric N/A meta.note 25
int_time Int_time Integration time s time.duration;obs.exposure 25
snr_rmtools_mad Snr_rmtools_mad Signal to noise ratio based the peak polarized intensity divided by the estimated noise in the Faraday depth spectrum (where the noise is computed using the median deviation from the median of the polarized intensity, and then correcting to be equivalent to a Gaussian sigma). N/A stat.snr;phot.flux;phys.polarization 25
nvss_rm_err Nvss_rm_err Error in rotation measure of the object in NVSS rad.m**-2 stat.error;phys.polarization.rotMeasure 25
lgz_ra_deg Lgz_ra_deg RA of the host galaxy, mainly from NED. deg pos.eq.ra 25
lgz_dec_deg Lgz_dec_deg Dec of the host galaxy, mainly from NED. deg pos.eq.dec 25
num_in_field Num_in_field Number of polarized sources in the originating pointing. N/A meta.number;src 25
medrm Medrm Median RM in the originating pointing. rad.m**-2 phys.polarization.rotMeasure;stat.median 25
madrm Madrm Median absolute deviation of RM in the originating pointing. rad.m**-2 stat.mad;phys.polarization.rotMeasure 25
medfpol Medfpol Median degree of polarization in the originating pointing (percent). N/A phys.polarization;stat.median 25
madfpol Madfpol Median absolute deviation of degree of polarization in the originating pointing (percent). N/A stat.mad;phys.polarization 25
ra_centre Ra_centre RA of field centre deg pos.eq.ra;obs.field 25
dec_centre Dec_centre Dec of field centre deg pos.eq.dec;obs.field 25
grmerr Grmerr Error in grm. Note galm rad.m**-2 stat.error;phys.polarization.rotMeasure 25
bzcat_name Bzcat_name Blazar source name in the ROMA-BZCAT catalogue (2015Ap&SS.357...75M) N/A meta.id.cross 25
catname Catname Name of catalog this was taken from. N/A meta.note 30
rm_method Rm_method RM determination method N/A meta.note 30
ionosphere Ionosphere Ionospheric correction method N/A meta.note 30
pol_bias Pol_bias Polarization bias correction method N/A meta.note 30
flux_type Flux_type Stokes extraction method N/A meta.note 30
channelwidth Channelwidth Typical channel width Hz em.freq;instr.bandwidth 30
telescope Telescope Name of Telescope(s) N/A instr.tel 30
obs_interval Obs_interval Interval of observation d time.interval 30
leakage Leakage Instrumental leakage estimate N/A phys.polarization.linear 30
i_nvss I_nvss Integrated Stokes I flux density from NVSS mJy phot.flux;phys.polarization.stokes.I 30
p_nvss P_nvss Average peak polarized intensity from NVSS mJy phot.flux;phys.polarization.stokes.I 30
pi_nvss Pi_nvss Percent polarization from NVSS N/A phys.polarization;arith.ratio 30
separation_nvss Separation_nvss Difference between NVSS position and LoTSS DR2 position arcsec pos.angDistance 30
lgz_size Lgz_size Largest angular size of the source arcsec phys.angsize;stat.max 30

Citation Info

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

Note galm

This is using Version 2 of the Galactic Faraday rotation sky at https://wwwmpa.mpa-garching.mpg.de/ ̃ensslin/research/data/faraday2020.html.