VLAM311P4G ivo://nasa.heasarc/vlam311p4g NASA/GSFC HEASARC Galvin, Filipovic 2026-07-17 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the Data Release 2 of the Point Source Catalog created from a series of previously constructed radio-continuum images of M 31 at a wavelength lambda of 20 cm (frequency nu = 1.4 GHz) from archived VLA observations. In total, the authors identify a collection of 916 unique discrete radio sources across the field of M 31. Comparing these detected sources with those listed by Gelfand et al. (2004, ApJS, 155, 89, HEASARC table VLAM31325M) at lambda = 92 cm (325 MHz), the spectral index of 98 sources has been derived. The majority (73%) of these sources exhibit a spectral index of alpha < -0.6, indicating that their emission is predominantly non-thermal in nature, which is typical for background objects and Supernova Remnants (SNRs). This table contains the integrated flux densities for 1,131 detections of 916 unique sources detected at 1.4 GHz in 28 VLA observations. Of these 916 unique sources, 109 were detected in at least two separate images. For such sources, the authors list a group identifier, a group count, and an average flux and error. Sources were cross referenced with the Gelfand et al. (2004) catalog of sources detected at 92 cm. For matched sources, the flux density at this wavelength and the derived spectral index between 20 and 92 cm are listed. This table was created by the HEASARC in May 2015 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/Other/Ser/189.15">CDS Catalog J/Other/Ser/189.15</a> file m31radio.dat. This is a service provided by NASA HEASARC . 2014SerAJ.189...15G https://heasarc.gsfc.nasa.gov/W3Browse/all/vlam311p4g.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=vlam311p4g& GET text/xml 180 99999 true 9.702125 39.8685 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=vlam311p4g GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_vlam311p4g&Action=More+Options&Action=Parameter+Search&ConeAdd=1 RADIO CATALOG 0.0166666666666667 Radio public vlam311p4g VLA M 31 1.4-GHz Source Catalog name Source Designation ([GF2014] VLA JHHMMSS+DDMMSS) 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_1p4_ghz Integrated Flux Density at 20 cm mJy phot.flux.density;em.radio.750-1500MHz double nullable vla_proj_seg_code VLA Project and Segment Code meta.code;obs char nullable flux_325_mhz Gelfand et al. (2004, J/ApJS/155/89) Integrated Flux Dens. at 92cm, If Available mJy phot.flux.density;em.radio.200-400MHz double nullable flux_325_mhz_error Error in Integrated Flux Density at 92 cm, If Available mJy stat.error;phot.flux.density;em.radio.200-400MHz double nullable spectral_index Derived Spectral Index spect.index;em.radio.200-400MHz;em.radio.750-1500MHz double nullable num_sources_in_group The Number of Sources in a Group meta.number short nullable avg_group_flux The Average Flux for a Group mJy phot.flux.density;em.radio.750-1500MHz double nullable bii Galactic Latitude degree pos.galactic.lat double nullable group_id Group Identifier for Common Sources meta.id.assoc short nullable lii Galactic Longitude degree pos.galactic.lon double nullable group_pos_flag Boolean Flag [01] Indicates Best 20-cm Source Position in a Group meta.code;pos short nullable avg_group_flux_error Error in Average Group Flux mJy stat.error;phot.flux.density;em.radio.750-1500MHz 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