The results of observations on the Large Phased Array of the Lebedev Physical Institute made as part of a survey of northern sky at 102.5 MHz are reported. Survey source lists for declination ranges 27.5-33.5 deg. and 67.5-70.5 deg. are given, together with their coordinates, flux densities and identifications with 4C objects. In total, there are 920 sources with flux densities S(102.5)>=3.0 Jy in the two zones, which cover over 0.73 steradians.
1400-MHz Survey of 1478 Abell Clusters of Galaxies
Short Name:
VIII/29A
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalog contains observations of Abell clusters of galaxies which were obtained with the Green Bank 91-m telescope at 1400 MHz with an angular resolution of 10'x11' (RAxDEC). This catalog extends the sample of clusters originally published in Owen (1974AJ.....79..427O). The primary goals of this survey were to observe all Abell (1958ApJS....3..211A, Cat. VII/4) clusters with m10 (magnitude of the tenth brightest galaxy in the cluster) less than or equal to 17.0 and declinations north of -19 degrees, to observe all clusters with richness>=3 regardless of m10, and to obtain observations of a representative sample of the rest of the catalog (m10>=17.0; richness<=2). The abelclus.dat file contains ALL 957 detected sources (also beyond 0.5 corrected Abell radii). It contains 525 sources within 0.5 corrected Abell radii, while the published table1.dat file contains 487 entries corresponding to 485 distinct sources (in 442 clusters). The catalog entries contains the flux density at 1400 MHz, the Abell cluster number, richness class, distance class, m10, redshift estimate (z), corrected Abell cluster radius, right ascension (B1950), declination (B1950), deconvolved major and minor source axis lengths, position angle, and distance of the source from the cluster center.
We present observations of the Lockman Hole with the Giant Metrewave Radio Telescope (GMRT). Twelve pointings were observed, covering a total area of ~5deg^2^ with a resolution of 6x5arcsec^2^, position angle +45deg. The majority of the pointings have an rms noise of ~60uJy/beam before correction for the attenuation of the GMRT primary beam. Techniques used for data reduction and production of a mosaicked image of the region are described, and the final mosaic is presented, along with a catalogue of 2845 sources detected above 6{sigma}. Radio source counts are calculated at 610-MHz and combined with existing 1.4-GHz source counts, in order to show that pure luminosity evolution of the local radio luminosity functions for active galactic nuclei and starburst galaxies is sufficient to account for the two source counts simultaneously.
We present further observations of the Lockman Hole field, made with the Giant Metrewave Radio Telescope at 610MHz with a resolution of 6x5arcsec^2^. These complement our earlier observations of the central ~5deg^2^ by covering a further ~8deg^2^, with an r.m.s. noise down to ~80uJy/beam. A catalogue of 4934 radio sources is presented
(from the authors) The Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands has been used to survey a section of the galactic plane at a radio frequency of 327MHz. Twenty-three overlapping synthesis fields were observed, covering galactic co-ordinates 43{deg}<l<91{deg}, |b|<1.6{deg}. Each field was observed at two epochs, several years apart, to identify variable sources. Intensity data from the separate epochs were combined, and the resulting images mosaiced to produce a single image of the entire survey region. Sensitivity of the mosaic is typically a few mJy. Resolution is 1' by 1'cosec(dec). The survey image provides our first high resolution view of the Galaxy at low radio frequencies, and includes sections of the Sagittarius and Cygnus arms. These sections contain numerous extended features, among them supernova remnants, HII regions, "bubbles" of thermal emission, and large patches of amorphous galactic thermal emission. The inter-arm region is characterized by lower densities of extended features, but numerous discrete compact radio sources, most of which are background objects such as quasars and other types of active galactic nuclei. However, the resolution, sensitivity and low frequency of this survey make it ideal for detecting weak, non-thermal compact galactic sources, e.g. compact, low surface brightness SNRs and radio stars. Inspection of the survey image has produced a catalog of nearly 4000 discrete sources with sizes less than about 3'.
Variability in 408MHz flux density, over a 1yr interval between 1995 and 1996, has been investigated using the DRAO Synthesis Telescope for a complete sample of 322 sources with S(408MHz)>80mJy at galactic b=15{deg}; four sources are found to show significant flux density variations.
We present the results of a recent re-reduction of the data from the Very Large Array (VLA) Low-frequency Sky Survey (VLSS). We used the VLSS catalogue as a sky model to correct the ionospheric distortions in the data and create a new set of sky maps and corresponding catalogue at 73.8MHz. The VLSS Redux (VLSSr) has a resolution of 75", and an average map rms noise level of {sigma}~0.1Jy/beam. The clean bias is 0.66x{sigma} and the theoretical largest angular size is 36'. Six previously unimaged fields are included in the VLSSr, which has an unbroken sky coverage over 9.3sr above an irregular southern boundary. The final catalogue includes 92964 sources. The VLSSr improves upon the original VLSS in a number of areas including imaging of large sources, image sensitivity, and clean bias; however the most critical improvement is the replacement of an inaccurate primary beam correction which caused source flux errors which vary as a function of radius to nearest pointing centre in the VLSS.
Microquasars are ideal natural laboratories for understanding accretion/ejection processes, studying the physics of relativistic jets, and testing gravitational phenomena. Nevertheless, these objects are difficult to find in our Galaxy. The main goal of this work is to increase the number of known systems of this kind, which should allow better testing of high-energy phenomena and more realistic statistical studies of this galactic population to be made. We have developed an improved search strategy based on positional cross-identification with very restrictive selection criteria to find new MQs, taking advantage of more sensitive modern X-ray data. To do this, we made combined use of the radio, infrared, and X-ray properties of the sources, using different available catalogs.
Infrared dark clouds are kinematically complex molecular structures in the interstellar medium that can host sites of massive star formation. We present maps measuring 4 square arcminutes of the ^12^CO, ^13^CO, and C^18^O J=3 to 2 lines from selected locations within the C and F (G028.37+00.07 and G034.43+00.24) infrared dark clouds (IRDCs), as well as single pointing observations of the ^13^CO and C^18^O J=2 to 1 lines towards three cores within these clouds. We derive CO gas temperatures throughout the maps and find that CO is significantly frozen out within these IRDCs. We find that the CO depletion tends to be the highest near column density peaks with maximum depletion factors between 5 and 9 in IRDC F and between 16 and 31 in IRDC C. We also detect multiple velocity components and complex kinematic structure in both IRDCs. Therefore, the kinematics of IRDCs seem to point to dynamically evolving structures yielding dense cores with considerable depletion factors.
We outline the theory and practice of measuring the four Stokes parameters of spectral lines in emission/absorption observations. We apply these concepts to our Arecibo H I absorption line data and present the results. We include a detailed discussion of instrumental effects arising from polarized beam structure and its interaction with the spatially extended emission line structure. At Arecibo, linear polarization [Stokes (Q,U)] has much larger instrumental effects than circular (Stokes V). We show how to reduce the instrumental contributions to V and to evaluate upper limits to its remaining instrumental errors by using the (Q,U) results. These efforts work well for opacity spectra but not for emission spectra. Arecibo's large central blockage exacerbates these effects, particularly for emission profiles, and other telescopes with weaker sidelobes are not as susceptible. We present graphical results for 41 sources; we analyze these absorption spectra in terms of Gaussian components, which number 136, and present physical parameters including magnetic field for each.
