Information on Service 'LoTSS DR2 Rotation Measures'

Further access options are discussed below

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:

scs.xml -- a standard SCS interface as defined by the IVOA to access catalog-type data; SCS clients use https://dc.zah.uni-heidelberg.de/lotsspol/q/cone/scs.xml? to access the service
form -- an interface for web browsers through an HTML form

Coverage

4.9628e-07 6.94792e-07 eV

2014.4 2020.09

This service is published as follows:

Within the set(s) ivo_managed with the renderer dali
Within the set(s) local,ivo_managed with the renderer form
Within the set(s) ivo_managed with the renderer scs.xml

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):

Name	Table Head	Description	Unit	UCD
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.

Name	Table Head	Description	Unit	UCD
_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.

Name	Table Head	Description	Unit	UCD	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.

Metadata

Identifier

Cite this

Description

Keywords

Creator

Created

Data updated

Metadata updated

Source