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LOF3C29546 - LOFAR 3C295 Field 46-MHz Source Catalog



This table contains the source list from Low Frequency Array (LOFAR) Low Band observations of the 3C 295 field at 46 MHz. The image of this field made at 46 MHz reaches a noise level of 8 mJy beam-1, making it the deepest image ever obtained at this frequency. In total, the authors detect 367 sources in the 3C 295 46-MHz field image, covering an area of 30.5 square degrees out to a primary-beam attenuation factor of 0.4. From these and simultaneous observations made at other low-band frequencies, the authors derive Euclidean-normalized differential source counts. The 62-MHz source counts agree with previous GMRT 153 MHz and Very Large Array 74 MHz differential source counts, scaling with a spectral index of -0.7. The authors find that a spectral index scaling of -0.5 is required to match up the LOFAR 34 MHz source counts. This result is also in agreement with source counts from the 38 MHz 8C survey, indicating that the average spectral index of radio sources flattens toward lower frequencies. The authors also find evidence for spectral flattening using the individual flux measurements of sources between 34 and 1400 MHz and by calculating the spectral index averaged over the source population. To select ultra-steep spectrum (alpha < -1.1) radio sources that could be associated with massive high-redshift radio galaxies, the authors compute spectral indices between 62 MHz, 153 MHz, and 1.4 GHz for sources in the Bootes field. They cross-correlate these radio sources with optical and infrared catalogs and fit the spectral energy distribution to obtain photometric redshifts. They find that most of these ultra-steep spectrum sources are located in the 0.7 <~ z <~ 2.5 range.

The Bootes and 3C 295 fields were simultaneously observed on 2012 April 12 as part of a multi-beam observation with the LOFAR LBA stations. The idea behind the multi-beam setup was to use the 3C 295 observations as a calibrator field to transfer the gain amplitudes to the (target) Bootes field. The pointing center of the 3C 295 field was J2000.0 RA, Dec = 14h 11m 20.9s, +52o 13' 55". The total integration time on both fields was 10.25 hr. The '46-MHz' observing band for the 3C 295 field observations was from 40 - 54 MHz, with 25 sub-bands more or less evenly distributed within this frequency range, with a total bandwidth of 4.9 MHz. The synthesized beam for this observation had dimensions of 40 arcseconds x 24 arcseconds. An overview of the observations is given in Table 1 of the reference paper, and an overview of the image characteristics in Table 2 of the reference paper.

Catalog Bibcode



LOFAR Low-band antenna observations of the 3C 295 and Bootes fields: source
counts and Ultra-Steep Spectrum sources

    van Weeren R.J., Williams W.L., Tasse C., Rottgering H.J.A.,
    Rafferty D.A., van der Tol S., Heald G., White G.J., Shulevski A.,
    Best P., Intema H.T., Bhatnagar S., Reich W., Steinmetz M.,
    van Velzen S., Ensslin T.A., Prandoni I., de Gasperin F., Jamrozy M.,
    Brunetti G., Jarvis M.J., McKean J.P., Wise M.W., Ferrari C.,
    Harwood J., Oonk J.B.R., Hoeft M., Kunert-Bajraszewska M., Horellou C.,
    Wucknitz O., Bonafede A., Mohan N.R., Scaife A.M.M., Klockner H.-R.,
    van Bemmel I.M., Merloni A., Chyzy K.T., Engels D., Falcke H.,
    Pandey-Pommier M., Alexov A., Anderson J., Avruch I.M., Beck R.,
    Bell M.E., Bentum M.J., Bernardi G., Breitling F., Broderick J.,
    Brouw W.N., Bruggen M., Butcher H.R., Ciardi B., de Geus E., de Vos M.,
    Deller A., Duscha S., Eisloffel J., Fallows .R.A., Frieswijk W.,
    Garrett M.A., Griessmeier J., Gunst A.W., Hamaker J.P., Hassall T.E.,
    Horandel J., van der Horst A, Iacobelli M., Jackson N.J., Juette E.,
    Kondratiev V.I., Kuniyoshi M., Maat P., Mann G., McKay-Bukowski D.,
    Mevius M., Morganti R., Munk H., Offringa A.R., Orru E., Paas H.,
    Pandey V.N., Pietka G., Pizzo R., Polatidis A.G., Renting A.,
    Rowlinson A., Schwarz D., Serylak M., Sluman J., Smirnov O.,
    Stappers B.W., Stewart A., Swinbank J., Tagger M., Tang Y.,
    Thoudam S., Toribio C., Vermeulen R., Vocks C., Zarka P.
   <Astrophys. J., 793, 82 (22pp) (2014>


This table was created by the HEASARC in January 2015 based on some of the contents of the machine-readable version of Table 3 from the reference paper, namely the 367 entries listing sources in the 3C 295 field detected at 46 MHz. The remaining entries in this table listing the sources detected in the Bootes field at a frequency of 62 MHz. and the sources detected in the 3C295 field at frequencies of 34 and 62 MHz, are available as the HEASARC tables LOFARBF62M, LOF3C29534 and LOF3C29562, respectively.


The radio source designation created by the HEASARC in the style recommended by the CDS Dictionary of Nomenclature of Celestial Objects, e.g., '[VWT2014] 3C295 46MHz J142124.9+352951', where the prefix stands for Van Weeren, Williams, Tasse 2015, the field name of 3C 295 and the observing frequency of 46 MHz.

The Right Ascension of the radio source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of of 10-5 degrees (0.036 arcseconds) in the original table.

The 1-sigma uncertainty in the Right Ascension of the radio source, in arcseconds.

The Declination of the radio source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of of 10-5 degrees (0.036 arcseconds) in the original table.

The 1-sigma uncertainty in the Declination of the radio source, in arcseconds.

The Galactic Longitude of the radio source.

The Galactic Latitude of the radio source.

The LOFAR integrated flux density of the radio source at 46 MHz, in mJy.

The 1-sigma uncertainty in the LOFAR integrated flux density of the radio source at 46 MHz, in mJy.

Contact Person

Questions regarding the LOF3C29546 database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 28-Jan-2015 13:55:49 EST