J/A+A/707/A198 LOFAR Two-metre Sky Survey (LoTSS) DR3 (Shimwell+, 2026)
The LOFAR Two-metre Sky Survey (LoTSS). VII. Third data release.
Shimwell T.W., Hardcastle M.J., Tasse C., Drabent A., Botteon A.,
Williams W.L., Best P.N., Roettgering H.J.A., Brueggen M., Brunetti G.,
Callingham J.R., Chyzy K.T., Conway J.E., De Gasperin F., Haverkorn M.,
Horellou C., Jackson N., Miley G.K., Morabito L.K., Morganti R.,
O'Sullivan S.P., Schwarz D.J., Smith D.J.B., van Weeren R.J.,
Vedantham H.K., White G.J., Ahmadi A., Alegre L., Arias M., Asabere B.,
Bahr-Kalus B., Barkus B., Bilicki M., Boehme L., Brentjens M.,
Brienza M., Bomans D.J., Bonafede A., Bonato M., Bonnassieux E.,
Boxelaar J.M., Camera S., Cassano R., Chilufya J., Cianfaglione M.,
Croston J.H., Cuciti V., Dabhade P., De Rubeis E., de Jong J.M.G.H.J.,
Dallacasa D., Dettmar R.J., Duncan K.J., Di Gennaro G., Edler H.W.,
Groeneveld C., Guerkan G., Hajduk M., Hale C.L., Heesen V., Hoang D.N.,
Hoeft M., Holties H., Horton M.A., Iacobelli M., Jamrozy M., Jarvis M.J.,
Jelic V., Kadler M., Kondapally R., Kunert-Bajraszewska M., Loose M.,
Magliocchetti M., Malek K., Manzano C., McKean J.P., Mevius M., Mingo B.,
Miskolczi A., Misra A., Moldon J., Nair D.G., Nakoneczny S.J., Orru E.,
Pashapour-Ahmadabadi M., Pasini T., Petley J., Pierce J.C.S., Prandoni I.,
Rafferty D., Rajpurohit K., Riseley C.J., Roberts I.D., Sethi S.,
Shulevski A., Stein M., Stuardi C., Sweijen F., ter Veen S., Timmerman R.,
Vaccari M., Wijnholds S.
<Astron. Astrophys. 707, A198 (2026)>
=2026A&A...707A.198S 2026A&A...707A.198S (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Radio continuum
Keywords: instrumentation: interferometers - catalogs - surveys -
radio continuum: general -
Abstract:
We present the third data release of the LOFAR Two-metre Sky Survey
(LoTSS-DR3). The survey images cover 88% of the northern
sky and were created from 12950 hrs of data (18.6 PB) accumulated
over 10.5 years. Producing the images took 20 million core hours of
processing through direction-independent and direction-dependent
calibration pipelines that correct for instrumental effects as well as
spatially and temporally varying ionospheric distortions. In our
120-168MHz continuum mosaic images with an angular resolution of 600
(900 below declination 10°) we catalogue 13667877 sources,
formed from 16,943,656 Gaussian components. The scatter in the
astrometric precision approximately follows the expected noise-like
behaviour but with an additional systematic component of at least
0.2400 that is likely due to calibration imperfections. The random
flux density scale error is 6%, while the systematic offset was
previously shown to be within 2%. The median sensitivity of our
mosaics is 92mJy/beam, improving to 68mJy/beam at high observing
elevations, but degrading to 183mJy/beam at the celestial equator due
to station area projection effects. Completeness simulations,
accounting for realistic source models, time- and bandwidth-smearing
effects, and astrometric errors, indicate that we detect more than 95%
of compact sources with integrated flux densities exceeding 9 times
the local root mean square (RMS) noise. However, the recovered source
counts in a particular integrated flux density bin do not match the
injected counts until flux densities exceed 45 times the local RMS
noise. The Euclidean-normalised differential source counts derived
from the survey constrain the radio source population over five orders
of magnitude and are in good agreement with previous deep and
wide-area surveys. All data products are publicly available, including
catalogues, individual-field Stokes I, Q, U, and V images, mosaicked
Stokes I images, and uv data with associated direction-dependent
calibration solutions.
Description:
The LOw-Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) Third
data release contains 120-168 MHz images covering 88% of the northern
sky. A catalogue of 13667877 radio components is derived from our
6" resolution total intensity (Stokes I) maps where the median
rms sensitivity is 92uJy/beam, improving to 68uJy/beam at high
observing elevations. The scatter in the astrometric precision
approximately follows the expected noise-like behaviour but with an
additional systematic component of at least 0.24arcsec that is likely
due to calibration imperfections. The random flux density scale error
is 6%, while the systematic offset was previously shown to be within
2%. All LoTSS-DR3 data products are publicly available, including
catalogues, individual-field Stokes I, Q, U, and V images, mosaicked
Stokes I images, and uv data with associated direction-dependent
calibration solutions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
lotssdr3.dat 310 13667877 Raw radio component catalogue of LoTSS-DR3
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See also:
J/A+A/622/A1 : LOFAR Two-metre Sky Survey DR1 source catalog (Shimwell+, 2019)
J/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)
https://lofar-surveys.org : LOFAR surveys home page
Byte-by-byte Description of file: lotssdr3.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Source The radio name of the source in the format
"ILTJHHMMSS.s+DDMMSS"
24- 38 F15.11 deg RAdeg Right ascension (J2000)
40- 49 F10.6 arcsec e_RAdeg ?=- Uncertainty in right ascension
51- 65 F15.11 deg DEdeg Declination (J2000)
67- 76 F10.6 arcsec e_DEdeg ?=- Uncertainty in declination
78- 89 E12.6 mJy/beam Speak Peak Stokes I flux density at 144MHz
per beam of the source
91-102 E12.6 mJy/beam e_Speak Uncertainty in peak Stokes I flux density
per beam of the source
104-115 E12.6 mJy SpeakTot Integrated Stokes I flux density at 144MHz
117-128 E12.6 mJy e_SpeakTot Uncertainty in integrated Stokes I flux
density
130-140 F11.6 arcsec Maj ?=- Fitted FWHM of the major axis of the
source
142-151 F10.6 arcsec e_Maj ?=- Uncertainty in FWHM of the fitted
major axis
153-162 F10.6 arcsec Min ?=- Fitted FWHM of the minor axis of the
source
164-173 F10.6 arcsec e_Min ?=- Uncertainty in FWHM of the fitted
minor axis
175-184 F10.6 arcsec DCMaj ?=- Deconvolved FWHM of the major axis of
the source
186-195 F10.6 arcsec e_DCMaj ?=- Uncertainty in deconvolved FWHM of
the major axis
197-207 F11.6 arcsec DCMin ?=- Deconvolved FWHM of the minor axis of
the source
209-218 F10.6 arcsec e_DCMin ?=- Uncertainty in deconvolved FWHM of
the minor axis
220-229 F10.6 deg PA []?=- Fitted position angle of the major
axis of the source measured east of north
231-240 F10.6 deg e_PA ?=- Uncertainty in fitted position angle
of the major axis of the source
242-251 F10.6 deg DCPA ?=- Deconvolved position angle of the major
axis of the source measured east of north
253-262 F10.6 deg e_DCPA ?=- Uncertainty in deconvolved position
angle of the major axis of the source
264-275 E12.6 mJy/beam Islrms RMS Average background RMS value of the
island in which the source is located
277-288 E12.6 mJy IslFTot Integrated Stokes I flux density of the
island in which the source is located
290-301 E12.6 mJy e_IslFTot Uncertainty in integrated Stokes I flux
density of the island
303 A1 --- SCode Source classification code (1)
305-308 I4 --- HEALPIX HEALPix pixel index of the source position,
computed at NSIDE = 16
310 I1 --- Res The angular resolution of the mosaic image
from which the source was extracted
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Note (1): Source classification code as follows:
S = a single-Gaussian source that is the only source in the island
C = a single-Gaussian source in an island with other sources
M = a multi-Gaussian source
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Acknowledgements:
Timothy Shimwell, shimwell(at)astron.nl
(End) Patricia Vannier [CDS] 04-Feb-2026