2022A&A...659A...1S

Query : 2022A&A...659A...1S

2022A&A...659A...1S - Astronomy and Astrophysics, volume 659A, 1-1 (2022/3-1)

The LOFAR Two-metre Sky Survey. V. Second data release.

SHIMWELL T.W., HARDCASTLE M.J., TASSE C., BEST P.N., ROTTGERING H.J.A., WILLIAMS W.L., BOTTEON A., DRABENT A., MECHEV A., SHULEVSKI A., VAN WEEREN R.J., BESTER L., BRUGGEN M., BRUNETTI G., CALLINGHAM J.R., CHYZY K.T., CONWAY J.E., DIJKEMA T.J., DUNCAN K., DE GASPERIN F., HALE C.L., HAVERKORN M., HUGO B., JACKSON N., MEVIUS M., MILEY G.K., MORABITO L.K., MORGANTI R., OFFRINGA A., OONK J.B.R., RAFFERTY D., SABATER J., SMITH D.J.B., SCHWARZ D.J., SMIRNOV O., O'SULLIVAN S.P., VEDANTHAM H., WHITE G.J., ALBERT J.G., ALEGRE L., ASABERE B., BACON D.J., BONAFEDE A., BONNASSIEUX E., BRIENZA M., BILICKI M., BONATO M., CALISTRO RIVERA G., CASSANO R., COCHRANE R., CROSTON J.H., CUCITI V., DALLACASA D., DANEZI A., DETTMAR R.J., DI GENNARO G., EDLER H.W., ENSSLIN T.A., EMIG K.L., FRANZEN T.M.O., GARCIA-VERGARA C., GRANGE Y.G., GURKAN G., HAJDUK M., HEALD G., HEESEN V., HOANG D.N., HOEFT M., HORELLOU C., IACOBELLI M., JAMROZY M., JELIC V., KONDAPALLY R., KUKRETI P., KUNERT-BAJRASZEWSKA M., MAGLIOCCHETTI M., MAHATMA V., MALEK K., MANDAL S., MASSARO F., MEYER-ZHAO Z., MINGO B., MOSTERT R.I.J., NAIR D.G., NAKONECZNY S.J., NIKIEL-WROCZYNSKI B., ORRU E., PAJDOSZ-SMIERCIAK U., PASINI T., PRANDONI I., VAN PIGGELEN H.E., RAJPUROHIT K., RETANA-MONTENEGRO E., RISELEY C.J., ROWLINSON A., SAXENA A., SCHRIJVERS C., SWEIJEN F., SIEWERT T.M., TIMMERMAN R., VACCARI M., VINK J., WEST J.L., WOLOWSKA A., ZHANG X. and ZHENG J.

Abstract (from CDS):

In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120-168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44°30' and 1h00m +28°00' and spanning 4178 and 1457 square degrees respectively. The images were derived from 3451 h (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4 396 228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 6'' resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 µJy beam^–1; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2''; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy beam^–1. By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of > ± 0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 20'' resolution 120-168 MHz continuum images have a median rms sensitivity of 95 µJy beam^–1, and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480 x 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8 mJy beam^–1 at 4' and 2.2 mJy beam^–1 at 20''; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data to facilitate the thorough scientific exploitation of this unique dataset.

Abstract Copyright: © ESO 2022

Journal keyword(s): surveys - catalogs - radio continuum: general - techniques: image processing

VizieR on-line data: <Available at CDS (J/A+A/659/A1): catalog.dat>

Nomenclature: ILT JHHMMSS.s+DDMMSS.s N=4396228.

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 23

Full paper

View the references in ADS

Number of rows : 23

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Mag R	Sp type	#ref 1850 - 2023	#notes
1	NGC 315	LIN	00 57 48.88334410	+30 21 08.8119345	12.80	12.20	11.16	11.26	~	769	2
2	3C 48	QSO	01 37 41.2996631208	+33 09 35.080388820		16.62	16.20		~	2765	2
3	SNR G132.6+01.5	SNR	02 17 40	+62 45.0					~	175	0
4	W 3	MoC	02 27 04.10	+61 52 27.1					~	1024	3
5	NAME Heart Nebula	HII	02 32.7	+61 27					~	313	1
6	ACO 399	ClG	02 57 56.4	+13 00 59					~	384	0
7	3C 196	Sy1	08 13 36.0561170112	+48 13 02.644966020		18.36	17.79		~	545	2
8	ACO 746	ClG	09 09 34.7638	+51 32 56.134					~	38	0
9	IC 2476	LIN	09 27 52.8290410824	+29 59 08.744484660		14.5			~	94	0
10	BD+44 2051	PM*	11 05 28.5769490063	+43 31 36.386948721	11.440	10.270		7.9	M1.0V	322	0
11	NVSS J114649+352829	Rad	11 46 49.4	+35 28 29					~	9	1
12	7C 1144+3517	BLL	11 47 22.1297825184	+35 01 07.538786184		17.89	16.83	10.26	~	170	1
13	G 122-49	PM*	11 50 57.7205259231	+48 22 38.561183125				12.95	M4.5V	110	0
14	NAME Virgo Cluster	ClG	12 26 32.1	+12 43 24					~	6504	0
15	NGC 4631	GiP	12 42 08.009	+32 32 29.44		9.78	9.19	9.10	~	1079	2
16	NAME NGP	reg	12 51 26.275	+27 07 41.70					~	1148	0
17	ACO 1656	ClG	12 59 44.40	+27 54 44.9					~	4694	2
18	NGC 5127	LIN	13 23 45.0315298080	+31 33 56.527040808		13.9			~	174	0
19	NAME Corona Borealis	SCG	15 25	+29.5					~	128	0
20	ELAIS N1	reg	16 10 01	+54 30.6					~	395	0
21	ACO 2255	ClG	17 12 50.04	+64 03 10.6					~	557	0
22	NAME NEP	reg	18 00 00.000	+66 33 38.55					~	338	0
23	NAME Cyg Loop	SNR	20 51.0	+30 40					~	898	0

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