LBCS: The LOFAR Long-Baseline Calibrator Survey

N. Jackson; A. Tagore; A. Deller; J. Moldón; E. Varenius; L. Morabito; O. Wucknitz; T. Carozzi; J. Conway; A. Drabent; A. Kapinska; E. Orrù; M. Brentjens; R. Blaauw; G. Kuper; J. Sluman; J. Schaap; N. Vermaas; M. Iacobelli; L. Cerrigone; A. Shulevski; S. ter Veen; R. Fallows; R. Pizzo; M. Sipior; J. Anderson; I. M. Avruch; M. E. Bell; I. van Bemmel; M. J. Bentum; P. Best; A. Bonafede; F. Breitling; J. W. Broderick; W. N. Brouw; M. Brüggen; B. Ciardi; A. Corstanje; F. de Gasperin; E. de Geus; J. Eislöffel; D. Engels; H. Falcke; M. A. Garrett; J. M. Grießmeier; A. W. Gunst; M. P. van Haarlem; G. Heald; M. Hoeft; J. Hörandel; A. Horneffer; H. Intema; E. Juette; M. Kuniyoshi; J. van Leeuwen; G. M. Loose; P. Maat; R. McFadden; D. McKay-Bukowski; J. P. McKean; D. D. Mulcahy; H. Munk; M. Pandey-Pommier; A. G. Polatidis; W. Reich; H. J. A. Röttgering; A. Rowlinson; A. M. M. Scaife; D. J. Schwarz; M. Steinmetz; J. Swinbank; S. Thoudam; M. C. Toribio; R. Vermeulen; C. Vocks; R. J. van Weeren; M. W. Wise; S. Yatawatta; P. Zarka

doi:10.1051/0004-6361/201629016

LBCS: The LOFAR Long-Baseline Calibrator Survey

N. Jackson, A. Tagore, A. Deller, J. Moldón, E. Varenius, L. Morabito, O. Wucknitz, T. Carozzi, J. Conway, A. Drabent, A. Kapinska, E. Orrù, M. Brentjens, R. Blaauw, G. Kuper, J. Sluman, J. Schaap, N. Vermaas, M. Iacobelli, L. CerrigoneA. Shulevski, S. ter Veen, R. Fallows, R. Pizzo, M. Sipior, J. Anderson, I. M. Avruch, M. E. Bell, I. van Bemmel, M. J. Bentum, P. Best, A. Bonafede, F. Breitling, J. W. Broderick, W. N. Brouw, M. Brüggen, B. Ciardi, A. Corstanje, F. de Gasperin, E. de Geus, J. Eislöffel, D. Engels, H. Falcke, M. A. Garrett, J. M. Grießmeier, A. W. Gunst, M. P. van Haarlem, G. Heald, M. Hoeft, J. Hörandel, A. Horneffer, H. Intema, E. Juette, M. Kuniyoshi, J. van Leeuwen, G. M. Loose, P. Maat, R. McFadden, D. McKay-Bukowski, J. P. McKean, D. D. Mulcahy, H. Munk, M. Pandey-Pommier, A. G. Polatidis, W. Reich, H. J. A. Röttgering, A. Rowlinson, A. M. M. Scaife, D. J. Schwarz, M. Steinmetz, J. Swinbank, S. Thoudam, M. C. Toribio, R. Vermeulen, C. Vocks, R. J. van Weeren, M. W. Wise, S. Yatawatta, P. Zarka

Astronomy

Research output: Contribution to journal › Article › Academic › peer-review

28 Citations (Scopus)

224 Downloads (Pure)

Abstract

We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (≳ 50 - 100 mJy) at frequencies around 110-190 MHz on scales of a few hundred milliarcseconds. At least for the 200-300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas - typically a few degrees - around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200-600 km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per sq. deg. Coherence times decrease from 1-3 min on 200-km baselines to about 1 min on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 min, is seen on the DE609 baseline, which at 227 km is close to being the shortest. We see median coherence times of between 80 and 110 s on the four longest baselines (580-600 km), and about 2 min for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 deg. Although source structures cannot be measured in these observations, we deduce that phase transfer is affected if the calibrator source structure is not known. We give suggestions for calibration strategies and choice of calibrator sources, and describe the access to the online catalogue and data products.

Original language	English
Article number	A86
Number of pages	13
Journal	Astronomy and Astrophysics
Volume	595
Issue number	November 2016
DOIs	https://doi.org/10.1051/0004-6361/201629016
Publication status	Published - 2016

Keywords

instrumentation: interferometers
techniques: interferometric
surveys
galaxies: active
radio continuum: galaxies

Access to Document

10.1051/0004-6361/201629016

LBCS: The LOFAR Long-Baseline Calibrator SurveyFinal publisher's version, 1.5 MBLicence: Unspecified

http://adsabs.harvard.edu/abs/2016A%26A...595A..86J

Handle.net

Persistent link

Cite this

Jackson, N., Tagore, A., Deller, A., Moldón, J., Varenius, E., Morabito, L., Wucknitz, O., Carozzi, T., Conway, J., Drabent, A., Kapinska, A., Orrù, E., Brentjens, M., Blaauw, R., Kuper, G., Sluman, J., Schaap, J., Vermaas, N., Iacobelli, M., ... Zarka, P. (2016). LBCS: The LOFAR Long-Baseline Calibrator Survey. Astronomy and Astrophysics, 595(November 2016 ), Article A86. https://doi.org/10.1051/0004-6361/201629016

@article{127b5ad1716c45fc80abe43b97ad8775,

title = "LBCS: The LOFAR Long-Baseline Calibrator Survey",

abstract = "We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (≳ 50 - 100 mJy) at frequencies around 110-190 MHz on scales of a few hundred milliarcseconds. At least for the 200-300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas - typically a few degrees - around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200-600 km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per sq. deg. Coherence times decrease from 1-3 min on 200-km baselines to about 1 min on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 min, is seen on the DE609 baseline, which at 227 km is close to being the shortest. We see median coherence times of between 80 and 110 s on the four longest baselines (580-600 km), and about 2 min for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 deg. Although source structures cannot be measured in these observations, we deduce that phase transfer is affected if the calibrator source structure is not known. We give suggestions for calibration strategies and choice of calibrator sources, and describe the access to the online catalogue and data products.",

keywords = "instrumentation: interferometers, techniques: interferometric, surveys, galaxies: active, radio continuum: galaxies",

author = "N. Jackson and A. Tagore and A. Deller and J. Mold{\'o}n and E. Varenius and L. Morabito and O. Wucknitz and T. Carozzi and J. Conway and A. Drabent and A. Kapinska and E. Orr{\`u} and M. Brentjens and R. Blaauw and G. Kuper and J. Sluman and J. Schaap and N. Vermaas and M. Iacobelli and L. Cerrigone and A. Shulevski and {ter Veen}, S. and R. Fallows and R. Pizzo and M. Sipior and J. Anderson and Avruch, {I. M.} and Bell, {M. E.} and {van Bemmel}, I. and Bentum, {M. J.} and P. Best and A. Bonafede and F. Breitling and Broderick, {J. W.} and Brouw, {W. N.} and M. Br{\"u}ggen and B. Ciardi and A. Corstanje and {de Gasperin}, F. and {de Geus}, E. and J. Eisl{\"o}ffel and D. Engels and H. Falcke and Garrett, {M. A.} and Grie{\ss}meier, {J. M.} and Gunst, {A. W.} and {van Haarlem}, {M. P.} and G. Heald and M. Hoeft and J. H{\"o}randel and A. Horneffer and H. Intema and E. Juette and M. Kuniyoshi and {van Leeuwen}, J. and Loose, {G. M.} and P. Maat and R. McFadden and D. McKay-Bukowski and McKean, {J. P.} and Mulcahy, {D. D.} and H. Munk and M. Pandey-Pommier and Polatidis, {A. G.} and W. Reich and R{\"o}ttgering, {H. J. A.} and A. Rowlinson and Scaife, {A. M. M.} and Schwarz, {D. J.} and M. Steinmetz and J. Swinbank and S. Thoudam and Toribio, {M. C.} and R. Vermeulen and C. Vocks and {van Weeren}, {R. J.} and Wise, {M. W.} and S. Yatawatta and P. Zarka",

note = "M1 - Journal Article",

year = "2016",

doi = "10.1051/0004-6361/201629016",

language = "English",

volume = "595",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = " EDP Sciences",

number = "November 2016 ",

}

Jackson, N, Tagore, A, Deller, A, Moldón, J, Varenius, E, Morabito, L, Wucknitz, O, Carozzi, T, Conway, J, Drabent, A, Kapinska, A, Orrù, E, Brentjens, M, Blaauw, R, Kuper, G, Sluman, J, Schaap, J, Vermaas, N, Iacobelli, M, Cerrigone, L, Shulevski, A, ter Veen, S, Fallows, R, Pizzo, R, Sipior, M, Anderson, J, Avruch, IM, Bell, ME, van Bemmel, I, Bentum, MJ, Best, P, Bonafede, A, Breitling, F, Broderick, JW, Brouw, WN, Brüggen, M, Ciardi, B, Corstanje, A, de Gasperin, F, de Geus, E, Eislöffel, J, Engels, D, Falcke, H, Garrett, MA, Grießmeier, JM, Gunst, AW, van Haarlem, MP, Heald, G, Hoeft, M, Hörandel, J, Horneffer, A, Intema, H, Juette, E, Kuniyoshi, M, van Leeuwen, J, Loose, GM, Maat, P, McFadden, R, McKay-Bukowski, D, McKean, JP, Mulcahy, DD, Munk, H, Pandey-Pommier, M, Polatidis, AG, Reich, W, Röttgering, HJA, Rowlinson, A, Scaife, AMM, Schwarz, DJ, Steinmetz, M, Swinbank, J, Thoudam, S, Toribio, MC, Vermeulen, R, Vocks, C, van Weeren, RJ, Wise, MW, Yatawatta, S & Zarka, P 2016, 'LBCS: The LOFAR Long-Baseline Calibrator Survey', Astronomy and Astrophysics, vol. 595, no. November 2016 , A86. https://doi.org/10.1051/0004-6361/201629016

TY - JOUR

T1 - LBCS

T2 - The LOFAR Long-Baseline Calibrator Survey

AU - Jackson, N.

AU - Tagore, A.

AU - Deller, A.

AU - Moldón, J.

AU - Varenius, E.

AU - Morabito, L.

AU - Wucknitz, O.

AU - Carozzi, T.

AU - Conway, J.

AU - Drabent, A.

AU - Kapinska, A.

AU - Orrù, E.

AU - Brentjens, M.

AU - Blaauw, R.

AU - Kuper, G.

AU - Sluman, J.

AU - Schaap, J.

AU - Vermaas, N.

AU - Iacobelli, M.

AU - Cerrigone, L.

AU - Shulevski, A.

AU - ter Veen, S.

AU - Fallows, R.

AU - Pizzo, R.

AU - Sipior, M.

AU - Anderson, J.

AU - Avruch, I. M.

AU - Bell, M. E.

AU - van Bemmel, I.

AU - Bentum, M. J.

AU - Best, P.

AU - Bonafede, A.

AU - Breitling, F.

AU - Broderick, J. W.

AU - Brouw, W. N.

AU - Brüggen, M.

AU - Ciardi, B.

AU - Corstanje, A.

AU - de Gasperin, F.

AU - de Geus, E.

AU - Eislöffel, J.

AU - Engels, D.

AU - Falcke, H.

AU - Garrett, M. A.

AU - Grießmeier, J. M.

AU - Gunst, A. W.

AU - van Haarlem, M. P.

AU - Heald, G.

AU - Hoeft, M.

AU - Hörandel, J.

AU - Horneffer, A.

AU - Intema, H.

AU - Juette, E.

AU - Kuniyoshi, M.

AU - van Leeuwen, J.

AU - Loose, G. M.

AU - Maat, P.

AU - McFadden, R.

AU - McKay-Bukowski, D.

AU - McKean, J. P.

AU - Mulcahy, D. D.

AU - Munk, H.

AU - Pandey-Pommier, M.

AU - Polatidis, A. G.

AU - Reich, W.

AU - Röttgering, H. J. A.

AU - Rowlinson, A.

AU - Scaife, A. M. M.

AU - Schwarz, D. J.

AU - Steinmetz, M.

AU - Swinbank, J.

AU - Thoudam, S.

AU - Toribio, M. C.

AU - Vermeulen, R.

AU - Vocks, C.

AU - van Weeren, R. J.

AU - Wise, M. W.

AU - Yatawatta, S.

AU - Zarka, P.

N1 - M1 - Journal Article

PY - 2016

Y1 - 2016

N2 - We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (≳ 50 - 100 mJy) at frequencies around 110-190 MHz on scales of a few hundred milliarcseconds. At least for the 200-300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas - typically a few degrees - around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200-600 km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per sq. deg. Coherence times decrease from 1-3 min on 200-km baselines to about 1 min on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 min, is seen on the DE609 baseline, which at 227 km is close to being the shortest. We see median coherence times of between 80 and 110 s on the four longest baselines (580-600 km), and about 2 min for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 deg. Although source structures cannot be measured in these observations, we deduce that phase transfer is affected if the calibrator source structure is not known. We give suggestions for calibration strategies and choice of calibrator sources, and describe the access to the online catalogue and data products.

AB - We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (≳ 50 - 100 mJy) at frequencies around 110-190 MHz on scales of a few hundred milliarcseconds. At least for the 200-300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas - typically a few degrees - around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200-600 km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per sq. deg. Coherence times decrease from 1-3 min on 200-km baselines to about 1 min on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 min, is seen on the DE609 baseline, which at 227 km is close to being the shortest. We see median coherence times of between 80 and 110 s on the four longest baselines (580-600 km), and about 2 min for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 deg. Although source structures cannot be measured in these observations, we deduce that phase transfer is affected if the calibrator source structure is not known. We give suggestions for calibration strategies and choice of calibrator sources, and describe the access to the online catalogue and data products.

KW - instrumentation: interferometers

KW - techniques: interferometric

KW - surveys

KW - galaxies: active

KW - radio continuum: galaxies

U2 - 10.1051/0004-6361/201629016

DO - 10.1051/0004-6361/201629016

M3 - Article

SN - 0004-6361

VL - 595

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

IS - November 2016

M1 - A86

ER -

LBCS: The LOFAR Long-Baseline Calibrator Survey

Abstract

Keywords

Access to Document

Handle.net

Fingerprint

Cite this