MOSTATLAS - Molonglo Observatory Synthesis Telescope ATLAS 843-MHz Source Catalog

Overview

At the faintest radio flux densities (S_1.4 < 10 mJy), conflicting results have arisen regarding whether there is a flattening of the average spectral index between a low radio frequency (325 or 610 MHz) and, for example, 1.4 GHz. The authors present a new catalog of 843-MHz radio sources in the European Large Area ISO Survey-South 1 (ELAIS-S1) field, which contains the sources, their Australia Telescope Large Area Survey (ATLAS) counterparts and the spectral index distribution of the sources as a function of flux density. The authors do not find any statistically significant evidence for a trend towards flatter spectral indices with decreasing flux density. In the reference paper, they investigate the spectral index distribution with redshift for those sources with reliable redshifts and explore the infrared properties. An initial sample of faint compact steep-spectrum sources in ATLAS are also presented, with a brief overview of their properties.

To obtain low-radio-frequency (843-MHz) data within the ATLAS ELAIS-S1 region (Middelberg et al. 2008, AJ, 135, 1276, the tables from which are available as the ATLASESID and ATLASESCPT tables in the HEASARC database), the authors used the Molonglo Observatory Synthesis Telescope (MOST). They have made 31 separate 12-h observations taken with MOST, which were combined into a single image with a spatial resolution of 62 arcsec x 43 arcsec.

Catalog Bibcode

2012MNRAS.421.1644R

References

Spectral index properties of milliJansky radio sources.
    Randall K.E., Hopkins A.M., Norris R.P., Zinn P.-C., Middelberg E.,
    Mao M.Y., Sharp R.G.
   <Mon. Not. R. Astron. Soc., 421, 1644-1660 (2012)>
   =2012MNRAS.421.1644R    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in January 2013 based on the CDS Catalog J/MNRAS/421/1644 file table1.dat.

Parameters

Name
The name for the MOST 843-MHz radio source. This was created by the HEASARC using the '[RHN2012]' prefix (for Randall, Hopkins, Norris 2012) and the J2000.0 equatorial coordinates in the style that we expect will be recommended by the Dictionary of Nomenclature of Celestial Objects for this catalog, e.g., '[RHN2012] J002945.68-432150.0'.

RA
The Right Ascension of the 843-MHz radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.001 seconds of time in the original table.

Dec
The Declination of the 843-MHz radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds in the original table.

LII
The Galactic Longitude of the 843-MHz radio source.

BII
The Galactic Latitude of the 843-MHz radio source.

Flux_843_MHz
The total integrated flux density I of the 843-MHz radio source, in mJy.

Flux_843_MHz_Error
The error in the total flux density of the 843-MHz radio source, in mJy. The authors use the process outlined in Hopkins et al. (2003, AJ, 125, 465) to calculate the errors associated with these measured flux densities, as detailed in equation (5) of Hopkins et al. (2003) with one small modification, viz., sigma_I = I * sqrt[2.5*(rms²/I²) + 0.05²], where I is the total integrated flux density, rms is the rms error in the image at the source location, and sigma_I is the total error on the integrated flux density. The authors use 0.05 as the sum of the squares of the instrumental and pointing errors as given in Middelberg et al. (2008), instead of 0.01 as given in Hopkins et al. (2003), due to the calibration accuracy of MOST being comparable to that of ATCA.

ATELAIS_Name
The ATLAS ELAIS-S1 IAU-style designation of the positionally closest ATLAS source to the MOST radio source.

FIRST_ATLAS_ID
The ATLAS ELAIS-S1 identification of the radio source component of the single/first match to the MOST 843-MHz radio source, e.g., 'S617'. The full names of these components in the HEASARC's ATLASESID and ATLASESCPT database tables have the prefix '[MNC2008]', e.g., '[MNC2008] S617'.

Source_Flag
This source flag parameter is set to non-blank values to indicate the following information for MOST 843-MHz sources that are also higher-frequency ATLAS sources :

    b = blended source (multiple 1.4 or 2.3 GHz sources within the MOST beam),
    p = single/point source in both MOST and ATLAS at all frequencies.

Other_ATLAS_IDs
The ATLAS ELAIS-S1 identification of other radio source components matching the MOST 843-MHz radio source in addition to the one listed in the first_atlas_id parameter value, e.g., 'S342,S339'. The full name of these components in the HEASARC's ATLASESID and ATLASESCPT database table have the prefix '[MNC2008]', e.g., '[MNC2008] S342'.

Flux_1p4_GHz
The total (integrated) 1.4-GHz flux density, in mJy, of the radio source components identified in the first_atlas_id and other_atlas_ids parameters, taken from Middelberg et al. (2008, AJ, 135, 1276).

Flux_1p4_GHz_Error
The error in the total (integrated) 1.4-GHz flux density, in mJy, of the radio source components identified in the first_atlas_id and other_atlas_ids parameters, taken from Middelberg et al. (2008, AJ, 135, 1276).

Conv_Flux_1p4_GHz
The total (integrated) 1.4-GHz flux density, in mJy, of the radio source components identified in the first_atlas_id and other_atlas_ids parameters, taken from Middelberg et al. (2008, AJ, 135, 1276) and then corrected and convolved to the MOST angular resolution.

Conv_Flux_1p4_GHz_Error
The error in the convolved total (integrated) 1.4-GHz flux density.

Flux_2p3_GHz
The total (integrated) 2.3-GHz flux density, in mJy, of the radio source components identified in the first_atlas_id and other_atlas_ids parameters, taken from Zinn et al. (in preparation).

Flux_2p3_GHz_Error
The error in the total (integrated) 2.3-GHz flux density, in mJy, of the radio source components identified in the first_atlas_id and other_atlas_ids parameters, taken from Zinn et al. (in preparation).

Spectral_Index
The three-point power-law (843 MHz, 1.4 and 2.3 GHz) spectral index, alpha (where S_nu ~ nu^alpha, and nu is the observer's frame frequency), found by fitting the available flux densities for the radio source.

Spectral_Index_Error
The error in the three-point power-law (843 MHz, 1.4 and 2.3 GHz) spectral index.

Lo_Spectral_Index
The low-frequency two-point power-law (843 MHz and 1.4 GHz) spectral index, alpha (where S_nu ~ nu^alpha, and nu is the observer's frame frequency), found by fitting the available flux densities for the radio source.

Lo_Spectral_Index_Error
The error in the low-frequency two-point power-law (843 MHz and 1.4 GHz) spectral index.

Hi_Spectral_Index
The high-frequency two-point power-law (1.4 and 2.3 GHz) spectral index, alpha (where S_nu ~ nu^alpha, and nu is the observer's frame frequency), found by fitting the available flux densities for the radio source.

Hi_Spectral_Index_Error
The error in the high-frequency two-point power-law (1.4 and 2.3 GHz) spectral index.

SWIRE_Name
The cross-identification with the Spitzer Wide-area Infra-Red Extragalactic survey (SWIRE).

IRAC_3p6_um_Flux
The IRAC 3.6-micron flux density of the SWIRE counterpart, in microJansky (µJy).

IRAC_4p5_um_Flux
The IRAC 4.5-micron flux density of the SWIRE counterpart, in microJansky (µJy).

IRAC_5p8_um_Flux
The IRAC 5.8-micron flux density of the SWIRE counterpart, in microJansky (µJy).

IRAC_8p0_um_Flux
The IRAC 8.0-micron flux density of the SWIRE counterpart, in microJansky (µJy).

MIPS_24_um_Flux
The MIPS 24-micron flux density of the SWIRE counterpart, in microJansky (µJy).

BJ_Mag
The B_J-band magnitude of the optical counterpart from the SuperCOSMOS Science Archive.

Rmag
The R-band magnitude of the optical counterpart from Rowan-Robinson et al. (2008, MNRAS, 386, 697, or 2004, MNRAS, 351, 1290).

Imag
The ESO-Spitzer Imaging extragalactic Survey (ESIS) VIMOS I-band magnitude of the counterpart from Berta et al. (2008, A&A, 488, 533).

Zmag
The ESO-Spitzer Imaging extragalactic Survey (ESIS) VIMOS z-band magnitude of the counterpart from Berta et al. (2008, A&A, 488, 533).

Redshift
The counterpart's photometric redshift from Rowan-Robinson et al. (2008, MNRAS, 386, 697, or 2004, MNRAS, 351, 1290), or (the HEASARC believes) spectroscopic redshift from Mao et al. (in preparation).

Comments
Comments concerning the specific source.

Contact Person

Questions regarding the MOSTATLAS database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:31:12 EDT