- ID:
- ivo://CDS.VizieR/J/AJ/77/405
- Title:
- Intense radio sources at 1400MHz (BDFL sample)
- Short Name:
- J/AJ/77/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate flux densities, precise positions of unresolved sources, and structures of resolved sources have been derived from full-beam and interferometric observations of intense sources at 1400 MHz. Results are given for 424 sources in the area of sky -5{deg}<{delta}<+70{deg}, |b|>5 whose 1400-MHz integrated flux densities S_1400_ exceed 1.70Jy [1 Jy (flux unit) = 10^-26^w/m^2^/Hz]. The 234 sources with S_1400_>=2.00Jy, equivalent diameters <10arcmin, and |b|>20{deg} form a 98+/-2% complete sample comparable in number to the 178-MHz Revised Third Cambridge Catalogue in this 4.30-sr area of sky, but selected at 1400MHz. This sample is suitable for statistical studies of the properties of extragalactic radio sources. To facilitate its use, and that of other samples which may be drawn from these data, references to other studies of the positions, fine and extended structure, polarization, and variability of the sources have been assembled in the principal table of this paper (Table 2). A comparison is made with other 1400-MHz flux-density data (Sec. 3), and the spectral content of the complete sample is discussed (Sec. 4).
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Search Results
- ID:
- ivo://CDS.VizieR/VIII/60
- Title:
- Interferometer phase calibration sources
- Short Name:
- VIII/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue contains compact radio sources with accurate positions observed with the Very Large Array (VLA). These sources are primarily intended for use as phase calibration sources for the Multi-Element Radio Linked Interferometer Network (MERLIN); the sources are also suitable as phase calibrators for the VLA and can be considered as candidate phase calibrators for very long-baseline interferometry (VLBI) networks. The accuracy of the position is 12 mas for sources in Paper I, 14 mas for sources in Paper II, and 55 mas for sources in Paper III.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/4937
- Title:
- Interplanetary scintillation at 162 and 1400MHz
- Short Name:
- J/MNRAS/474/4937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first astrophysical application of the technique of wide-field interplanetary scintillation (IPS) with the Murchison Widefield Array (MWA). This powerful technique allows us to identify and measure sub-arcsecond compact components in low-frequency radio sources across large areas of sky without the need for long-baseline interferometry or ionospheric calibration. We present the results of a 5-min observation of a 30x30deg^2^ MWA field at 162MHz with 0.5s time resolution. Of the 2550 continuum sources detected in this field, 302 (12 per cent) show rapid fluctuations caused by IPS. We find that at least 32 per cent of bright low-frequency radio sources contain a sub-arcsecond compact component that contributes over 40 per cent of the total flux density. Perhaps surprisingly, peaked-spectrum radio sources are the dominant population among the strongly scintillating, low-frequency sources in our sample. While gamma-ray active galactic nuclei are generally compact, flat-spectrum radio sources at higher frequencies (162MHz), the properties of many of the Fermi blazars in our field are consistent with a compact component embedded within more extended low-frequency emission. The detection of a known pulsar in our field shows that the wide-field IPS technique is at the threshold of sensitivity needed to detect new pulsars using image plane analysis, and scaling the current MWA sensitivity to that expected for SKA-low implies that large IPS-based pulsar searches will be feasible with SKA. Calibration strategies for the SKA require a better knowledge of the space density of compact sources at low radio frequencies, which IPS observations can now provide.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/2965
- Title:
- Interplanetary scintillation at 79 and 158MHz
- Short Name:
- J/MNRAS/473/2965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first dedicated observations of Interplanetary Scintillation (IPS) with the Murchison Widefield Array. We have developed a synthesis imaging technique, tailored to the properties of modern 'large-N' low-frequency radio telescopes. This allows us to image the variability on IPS time-scales across 900deg^2^ simultaneously. We show that for our observations, a sampling rate of just 2Hz is sufficient to resolve the IPS signature of most sources. We develop tests to ensure that IPS variability is separated from ionospheric or instrumental variability. We validate our results by comparison with existing catalogues of IPS sources, and near-contemporaneous observations by other IPS facilities. Using just 5 min of data, we produce catalogues at both 79 and 158MHz, each containing over 350 scintillating sources. At the field centre, we detect approximately one scintillating source per square degree, with a minimum scintillating flux density at 158MHz of 110mJy, corresponding to a compact flux density of approximately 400mJy. Each of these sources is a known radio source, however only a minority were previously known to contain sub-arcsecond components. We discuss our findings and the prospects they hold for future astrophysical and heliospheric studies.
- ID:
- ivo://CDS.VizieR/J/A+A/403/555
- Title:
- Interplanetary Scintillation Pushchino Survey
- Short Name:
- J/A+A/403/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr have been cross-identified with objects from the 7C and FIRST catalogues. We have obtained improved positions of IPS radio sources, which are necessary for their optical identification. The data on sizes and morphology provided by the FIRST catalogue have shown that more than 50% of IPS radio sources are single and compact (<3") at {nu}=1400MHz. Most of them belong to the class of compact steep spectrum radio sources. About 15% of IPS radio sources are single partially resolved FIRST objects (sizes of 3"-9") and another 11% are double radio sources with compact components. The remaining 22% have larger sizes and, as a rule, a more complex structure too. Because IPS sources certainly contain an appreciable part of their radiation at low frequencies (100MHz) in very compact (~0.1") components and have steep spectra, we hope that a significant part of the Pushchino Survey objects are very probable candidates for steep spectrum quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/421/455
- Title:
- Interplanetary Scintillation Pushchino Survey II
- Short Name:
- J/A+A/421/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical identification of 248 interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr with the center at RA=10h28m, DE=+41{deg}. All 260 counterparts of IPS radio sources from the 7C and FIRST catalogues, which had been found in Paper I (Cat. <J/A+A/403/555>), were considered. We used USNO-B1.0 catalogue (limiting magnitude m_R_~21) for the optical identification and searched the literature to find optical data for fainter objects. Photometric and spectroscopic observations were conducted on the 1m and 6m telescopes of SAO RAS. Optical magnitudes or deep limits for 22 objects and redshifts for 26 ones have been obtained. In total, we collected optical data for 116 (68 with redshift) counterparts of the PS radio sources. For the subsample of the PS quasars (41 objects) the redshift distribution was compared to those of several other samples of quasars (BRL, 3CRR, MQS, B3-VLA, 7CRS I-III and PKS 0.25Jy) which have complete or nearly complete redshift information.
- ID:
- ivo://CDS.VizieR/J/MNRAS/229/589
- Title:
- Interplanetary Scintillation Survey at 81.5 MHz
- Short Name:
- J/MNRAS/229/589
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of 1789 radio sources which exhibit interplanetary scintillation (IPS) at 81.5 MHz is presented. The angular diameters of scintillating components in the range 0.2-2 arcsec are listed together with values of the scintillating flux density at a solar elongation of 90 deg. IPS selects those sources which are highly compact, such as pulsars and some unusual extragalactic sources, or those in which energy is being released from active beams in the outer lobes of intrinsically powerful radio galaxies and quasars. The survey was made with the 3.6-hectare array at Cambridge and covers the area of sky between declinations -10 deg and +83 deg at all values of right ascension. The array was operated as a north-south phase-switching interferometer observing sources near meridian transit. Sixteen declination beams were produced covering the observed declination range. The half-power width of a declination beam is 5.5 sec(52.16-DEC) degrees, where DEC is the declination of peak beam response. The half-power beam width in right ascension is 107 sec(delta) s for a source at declination delta. The faintest sources in the catalogue have scintillating flux densities of about 0.3 Jy rms at a solar elongation of 90 deg, and total flux densities of about 5 Jy at 81.5 MHz. The sensitivity of the survey is not uniform over the sky, being determined largely by the galactic background emission. The flux density corresponding to one source per beam area in this survey is about 2.3 Jy at 81.5 MHz so that confusion errors are likely to be significant for total flux density S <= 20 Jy.
- ID:
- ivo://CDS.VizieR/J/ApJS/165/439
- Title:
- Interstellar scintillation at 2 and 8GHz
- Short Name:
- J/ApJS/165/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From 1979 to 1996 the Green Bank Interferometer was used by the Naval Research Laboratory to monitor the flux density from 146 compact radio sources at frequencies near 2 and 8GHz. We filter the light curves to separate intrinsic variations on times of a year or more from more rapid interstellar scintillation (ISS) on times of 550 days. Whereas the intrinsic variation at 2GHz is similar to that at 8GHz (although diminished in amplitude), the ISS variation is much stronger at 2 than at 8GHz. We characterize the ISS variation by an rms amplitude and a timescale and examine the statistics of these parameters for the 121 sources with significant ISS at 2GHz. We model the scintillations using the NE2001 Galactic electron model assuming the sources are brightness-limited.
- ID:
- ivo://CDS.VizieR/B/iram
- Title:
- IRAM Observation Logs
- Short Name:
- B/iram
- Date:
- 04 Jan 2022 15:31:49
- Publisher:
- CDS
- Description:
- The Institut de Radio Astronomie Millimetrique (IRAM) was founded in 1979 and is operated as a French-German-Spanish collaboration. Its partner institutes are the CNRS (Centre National de la Recherche Scientifique, France), the MPG (Max Planck Gesellschaft, Germany), and the IGN (Instituto Geografico Nacional, Spain). The principal activity of IRAM is the study of cold matter (molecular gas and dust) in the solar system, in our Galaxy, and out to cosmological distances in order to determine its composition, density, mass, temperature, and kinematics. IRAM operates two observatories at millimeter wavelengths which are open to the international astronomical community: The 30-m single-dish telescope on Pico Veleta (2850m), Spain, and the six-antenna interferometer on the Plateau de Bure (2550m) in France. Both sites are at high altitude to reduce the absorption by water vapor. The observatories are supported by the IRAM offices and laboratories in Granada and Grenoble. The observation log included here concerns the Plateau de Bure site, and summarizes the observations made there from December 1990. The observations log of the 30-m single-dish telescope covers a period starting in January 2009. This log was produced using a header archive, a collaborative effort between IRAM and IAA/CSIC. NOEMA (NOrthern Extended Millimeter Array) is the successor to the Plateau du Bure observatory. During its history, the observatory at the Plateau de Bure underwent several track extensions, received additional antennas (all of 15m diameter and similar construction as the first ones) and technical upgrades. From a three antenna interferometer with a maximum baseline of 288 meters in 1988, it has evolved to a eight-antenna array with baselines up to 760 meters in 2016. With the inauguration of the seventh antenna in September 2014, the observatory has started its transformation into NOEMA.
- ID:
- ivo://CDS.VizieR/J/A+A/507/241
- Title:
- IR and 610MHz observations in MGRO J2019+37
- Short Name:
- J/A+A/507/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MGROJ2019+37 is an unidentified extended source of very high energy gamma-rays originally reported by the Milagro Collaboration as the brightest TeV source in the Cygnus region. Its extended emission could be powered by either a single or several sources. The GeV pulsar AGL J2020.5+3653 discovered by AGILE and associated with PSR J2021+3651 could contribute to the emission from MGRO J2019+37. The aim of this paper is to identify radio and near-infrared sources in the field of the extended TeV source MGRO J2019+37, and study potential counterparts to explain its emission. We surveyed a region of about 6 square degrees with the Giant Metrewave Radio Telescope (GMRT) at the frequency 610MHz. We also observed the central square degree of this survey in the near-infrared Ks-band using the 3.5m telescope in Calar Alto. Archival X-ray observations of some specific fields are included. VLBI observations of an interesting radio source were performed. We explored possible scenarios to produce the multi-TeV emission from MGRO J2019+37 and studied which of the sources could be the main particle accelerator.
