VLALH1400M ivo://nasa.heasarc/vlalh1400m NASA/GSFC HEASARC Ibar et al. 2026-07-17 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source In the run-up to routine observations with the upcoming generation of radio facilities, the nature of the sub-mJy radio population has been hotly debated. In this paper, the authors describe multi-frequency data designed to probe the emission mechanism that dominates in these faint radio sources. Their analysis is based on observations of the Lockman Hole (LH) using the Giant Metrewave Radio Telescope (GMRT) near Pune, India - the deepest 610-MHz imaging yet reported - together with 1.4-GHz imaging from the Very Large Array (VLA), which are well matched in resolution and sensitivity to the GMRT data: sigma<sub>610MHz</sub> ~ 15 µJy/beam (µJy/beam), sigma}<sub>1.4GHz</sub> ~ 6 µJy/beam, and full width at half-maximum (FWHM) ~ 5 arcseconds. The GMRT and VLA data are cross-matched to obtain the radio spectral indices for the faint radio emitters. During six 12-hr sessions in 2006 February and July, the authors obtained data at 610 MHz for three pointings (FWHM ~ 43 arcminutes) in the LH (see Table 1 of the reference paper for full details), separated by 11 arcminutes (the LOCKMAN-E, LOCK-3 and LHEX-4 fields), typically with 28 of the 30 antennas that comprise the GMRT. The total integration time in each field, after overheads, was 16 hr. The final image had a noise level in the central 100 arcmin<sup>2</sup> of 14.7 µJy/beam, the deepest map reported at 610 MHz as of the date of publication, despite the modest integration time. New and archival data were obtained at the same three positions using the National Radio Astronomy Observatory's VLA, largely in its B configuration. This table contains 1450 sources found in the LH field at 1400 MHz by the VLA. For 17 of the sources which have multiple components, the 29 individual components are listed as well. Thus, the final table contains 1479 (1450 + 29) entries. Source extraction was based on criteria of peak brightness > 5 times the local rms and integrated flux density > 3 times the local rms. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/397/281">CDS Catalog J/MNRAS/397/281</a> file table4.dat. This is a service provided by NASA HEASARC . 2009MNRAS.397..281I https://heasarc.gsfc.nasa.gov/W3Browse/all/vlalh1400m.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=vlalh1400m& GET text/xml 180 99999 true 162.98270833 56.93183333 0.0833333333333333 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=vlalh1400m GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_vlalh1400m&Action=More+Options&Action=Parameter+Search&ConeAdd=1 RADIO CATALOG 0.0833333333333333 Radio public vlalh1400m VLA Lockman Hole 1400-MHz Radio Source Catalog name Source Designation ([IIB2009] LH1.4GHz JHHMMSS.s+DDMMSSa) meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable flux_1400_mhz Integrated Flux Density at 1.4 GHz mJy phot.flux.density;em.radio.750-1500MHz double nullable flux_1400_mhz_error RMS Uncertainty in Integrated Flux Density mJy stat.error;phot.flux.density;em.radio.750-1500MHz double nullable spectral_index_limit Limit Flag for Spectral Index meta.code;spect.index char nullable spectral_index Radio Spectral Index (Alpha) Between 610MHz and 1.4GHz spect.index double nullable spectral_index_pos_err Upper Uncertainty for Spectral Index stat.error;spect.index double nullable spectral_index_neg_err Lower Uncertainty for Spectral Index stat.error;spect.index double nullable bw_smear_corr Bandwidth Smearing Correction Factor meta.code double nullable snr_1400_mhz Peak Flux to Local Noise Ratio stat.snr;phot.flux.density;em.radio.750-1500MHz short nullable maximum_angular_size Observed Maximum Angular Size arcsec phys.angSize double nullable spectral_index_quality Flag [OU] Indicates (O)utside Cross-Match Region or (U)nreliable Spectral Index meta.code.qual;spect.index char nullable position_angle Orientation Angle (Position Angle) of the Source with Respect to North degree pos.posAng short nullable lii Galactic Longitude degree pos.galactic.lon double nullable spectral_index_flag Spectral Flag(s) meta.code;spect.index char nullable source_type_flag Flag Indicates Sources Extracted from the Convolved Area_beam_*sqrt(2) Image meta.code;src.class char nullable source_type Flag Indicates (M)=Extended or (S)ingle, (D)ouble, or (T)riple Components src.class char nullable bii Galactic Latitude degree pos.galactic.lat double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable