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 = 14^h 11^m 20.9^s, +52^o 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. 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. This is a service provided by NASA HEASARC .

This table contains the source list from Low Frequency Array (LOFAR) Low Band observations of the 3C 295 field at 34 MHz. The image of this field made at 34 MHz reaches a noise level of 12 mJy beam^-1, making it the deepest image ever obtained at this frequency. In total, the authors detect 392 sources in the 3C 295 34-MHz field image, covering an area of 52.3 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 = 14^h 11^m 20.9^s, +52^o 13' 55". The total integration time on both fields was 10.25 hr. The '34-MHz' observing band for the 3C 295 field observations was from 30 - 40 MHz, with 21 sub-bands more or less evenly distributed within this frequency range, with a total bandwidth of 4.1 MHz. The synthesized beam for this observation had dimensions of 56 arcseconds x 30 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. 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 392 entries listing sources in the 3C 295 field detected at 34 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 46 and 62 MHz, are available as the HEASARC tables LOFARBF62M, LOF3C29546 and LOF3C29562, respectively. This is a service provided by NASA HEASARC .

This table contains the source list from Low Frequency Array (LOFAR) Low Band observations of the Bootes field at 62 MHz. The images of this field and the 3C 295 field made at 62 MHz reach a noise level of 5 mJy beam^-1, making them the deepest images ever obtained at this frequency. In total, the authors detect 329 sources in the Bootes 62-MHz field image, covering an area of 19.4 square degrees out to a primary-beam attenuation factor of 0.4. From the observations, 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 (pointing center of J2000.0 RA and Dec of 14^h 32^m 03.0^s, +34^o 16' 33"). The total integration time on both fields was 10.25 hr. The observing band for the Bootes field observations was centered at 62 MHz, with a bandwidth of 16 MHz. The synthesized beam for this observation had dimensions of 31 arcseconds x 19 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. 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 329 entries listing sources in the Bootes field detected at 62 MHz. The remaining entries in this table listing the sources detected in the 3C295 field at frequencies of 34, 46 and 62 MHz are available as the HEASARC tables LOF3C29534, LOF3C29546 and LOF3C29562, respectively. This is a service provided by NASA HEASARC .

This table contains some of the results of Low-Frequency Array (LOFAR) High-Band Array (HBA) observations of the Herschel-ATLAS North Galactic Pole (NGP) survey area. The survey the authors carried out, consisting of four pointings covering around 142 deg² of sky in the frequency range 126-173 MHz, does not provide uniform noise coverage but otherwise is representative of the quality of data to be expected in the planned LOFAR wide-area surveys, and has been reduced using recently developed 'facet calibration' methods at a resolution approaching the full resolution of the data sets (~10 x 6 arcsec) and an rms off-source noise that ranges from 100 µJy beam^-1 in the center of the best fields to around 2 mJy/beam at the furthest extent of their imaging. In the reference paper, the authors describe the imaging, cataloguing and source identification processes, and present some initial science results based on a 5-sigma source catalog. These include (i) an initial look at the radio/far-infrared correlation at 150 MHz, showing that many Herschel sources are not yet detected by LOFAR; (ii) number counts at 150 MHz, including, for the first time, observational constraints on the numbers of star-forming galaxies; (iii) the 150-MHz luminosity functions for active and star-forming galaxies, which agree well with determinations at higher frequencies at low redshift, and show strong redshift evolution of the star-forming population; and (iv) some discussion of the implications of these observations for studies of radio galaxy life cycles. The NGP field was observed in four separate pointings, chosen to maximize the area of sky covered, with the LOFAR HBA as part of the Surveys Key Science project. These observations used the HBA_DUAL_INNER mode, meaning that the station beams of core and remote stations roughly matched each other and giving the widest possible field of view. The first observation, which was made early on in LOFAR operations, was of slightly longer duration (~10 h) than the others (~8 h). International stations were included in some of the observations in 2014 but were not used in any of the authors' analysis, which uses only the Dutch array. The author were interested in imaging in several separate frequency ranges (which are referred to hereafter as 'spectral windows'), since they wanted to be able to measure in-band spectral indices for detected sources. In addition, facet calibrating in different spectral windows could be done in parallel, speeding the processing up considerably. Accordingly, they chose to facet calibrate with six spectral windows, each made up of four bands and thus containing about 8 MHz of bandwidth:

 Spectral Nominal Frequency Frequency Range Window (MHz) (MHz) 1 130 126 - 134 2 138 134 - 142 3 146 142 - 150 4 154 150 - 158 5 161 158 - 166 6 169 166 - 173 

The final source catalog was made by combining the four per-field catalogs. Ideally, the authors would have combined the images of each field and done source finding on a mosaicked image, but this proved computationally intractable given the very large image cubes that result from having six spectral windows. They therefore merged the catalogs by identifying the areas of sky where there is overlap between the fields and choosing those sources which are measured from the region with the best rms values. This should ensure that there are no duplicate sources in the final catalog. The final master catalogue contains 17,132 sources and is derived from images covering a total of 142.7 deg² of independently imaged sky, with widely varying sensitivity. Total HBA-band (150-MHz) flux densities of catalogued sources detected using the PYBDSM software and a 5-sigma detection threshold range from a few hundred µJy to 20 Jy, with a median of 10 mJy. The authors examined all sources in the initial master catalog for associations with sources in other surveys, for rejection as artifacts, and for optical identifications,